Understand the difference. Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.
First referenceCurrent transformer · CT Voltage transformer · VT / PT Circuit breaker · CB Disconnector · Isolator Load-break switch · LBS Earthing switch · ES Fuse · FU Busbar · Bus Normally open contact · NO Normally closed contact · NC Changeover contact · CO Relay coil · Coil Contactor · KM Normally open pushbutton · PB NO Normally closed pushbutton · PB NC Emergency-stop operator · E-stop Selector switch · SS Indicator lamp · Lamp Terminal connection · Terminal CT test terminal · CT test Power transformer · TX Generator · GEN Three-phase motor · M PLC input / output · PLC I/O Capacitor · C Resistor · R Protective earth · PE Battery · BAT Power converter / inverter · PCS Single-pole circuit breaker · CB 1P Thermal circuit breaker · CB TH Thermal-magnetic circuit breaker · CB TM Current-limiting circuit breaker · CB LIM Residual-current circuit breaker · RCCB Residual-current breaker with overcurrent protection · RCBO Circuit breaker with undervoltage release · CB UV Circuit breaker with electronic trip unit · CB ETU Miniature circuit breaker · MCB Moulded-case circuit breaker · MCCB Air circuit breaker · ACB Additional circuit-breaker pole · CB POLE Switch-disconnector · SD Lockable disconnector · DS LOCK Lockable switch-disconnector · SD LOCK Three-position disconnector · DS 3POS Semiconductor power switch · SSW Unidirectional semiconductor power switch · SSW UNI Two-pole power switch · SW 2P Disconnector auxiliary NO contact · DS AUX NO Disconnector auxiliary NC contact · DS AUX NC Fused switch · SW FUSE Fuse-switch · FUSE SW Additional fused-switch pole · FUSE POLE General-purpose full-range fuse · gG Motor short-circuit fuse · aM Motor full-range fuse · gM Current transformer with two secondaries · CT 2SEC Tapped-secondary current transformer · CT TAP Current transformer with primary conductor indication · CT PRI Core-balance current transformer · CBCT Residual connection of phase CTs · CT RES Single-phase two-winding transformer · TX 1PH Electrostatically screened transformer · TX SCREEN Three-winding transformer · TX 3W Adjustable-ratio transformer · TX ADJ Single-phase autotransformer · AT 1PH Three-phase star autotransformer · AT 3PH Y Star-delta transformer · TX Y-D Delta-star transformer · TX D-Y Delta-delta transformer · TX D-D Star-star transformer · TX Y-Y Star-zigzag transformer · TX Y-Z Star-star-delta three-winding transformer · TX Y-Y-D Delta winding connection · DELTA Open-delta winding connection · OPEN D Star winding connection · STAR Y Star winding with accessible neutral · Y N Zigzag winding connection · ZIGZAG Mechanically latched relay coil · K LATCH Relay reset coil · K RESET Solid-state relay · SSR Polarised relay coil · K POL AC relay coil · K AC High-speed relay · K FAST Measuring relay · K MEAS Relay coil with diode suppression · K DIODE Relay coil with diode and LED · K D LED Relay coil with capacitor suppression · K CAP Relay coil with RC suppression · K RC Counter relay with manual reset · COUNT MAN Counter relay with electrical reset · COUNT ELEC Non-resettable counter relay · COUNT TOTAL On-delay timer relay · TON Off-delay timer relay · TOFF On-delay normally-open contact · TON NO On-delay normally-closed contact · TON NC Off-delay normally-open contact · TOFF NO Off-delay normally-closed contact · TOFF NC Maintained normally-open contact · NO HOLD Maintained normally-closed contact · NC HOLD Manually unlatched NO contact · NO UNLATCH Manually unlatched NC contact · NC UNLATCH Early-make normally-open contact · NO EARLY Late-make normally-open contact · NO LATE Early-break normally-closed contact · NC EARLY Late-break normally-closed contact · NC LATE Make-before-break changeover contact · MBB Motor overload trip NC contact · OL NC Motor overload alarm NO contact · OL NO Illuminated normally-open pushbutton · PB NO LAMP Illuminated normally-closed pushbutton · PB NC LAMP Maintained normally-open pushbutton · PB NO HOLD Maintained normally-closed pushbutton · PB NC HOLD Key-operated normally-open switch · KEY NO Key-operated normally-closed switch · KEY NC Latched key-operated switch · KEY HOLD Pull-cord switch · PULL CORD Foot-operated switch · FOOT Lever-operated switch · LEVER Three-position maintained selector · SEL 3 HOLD Three-position selector returning from left · SEL 3 LRET Three-position selector returning from right · SEL 3 RRET Three-position centre-return selector · SEL 3 CRET Three-position key selector · KEY SEL 3 Four-position maintained selector · SEL 4 HOLD Four-position key selector · KEY SEL 4 Normally-open limit switch · LS NO Normally-closed limit switch · LS NC Roller-operated limit switch · LS ROLLER Cam-operated limit switch · LS CAM Pressure switch NO · PS NO Pressure switch NC · PS NC Temperature switch NO · TS NO Temperature switch NC · TS NC Self-operating thermal switch · TS SELF Float level switch NO · LS FLOAT NO Float level switch NC · LS FLOAT NC Liquid flow switch · FS LIQ Gas flow switch · FS GAS Inductive proximity switch · PROX IND Three-wire inductive proximity switch · PROX IND 3W Capacitive proximity switch · PROX CAP Magnetic proximity switch · PROX MAG Photoelectric emitter-receiver switch · PHOTO Thermocouple · TC Resistance temperature detector · RTD Voltmeter · V Ammeter · A Power-factor meter · PF Phase-angle meter · PHASE Frequency meter · Hz Temperature indicator · TEMP Tachometer · RPM Running-hours meter · HOURS Ampere-hour meter · Ah Recording wattmeter · W REC Reactive-power meter · var Synchronoscope · SYNC SCOPE Active-power indicator · kW Differential voltmeter · DELTA V Active-energy meter · kWh Reactive-energy meter · kvarh Maximum-current monitoring relay · I HIGH Minimum-current monitoring relay · I LOW Current window monitoring relay · I WINDOW Differential-current measuring relay · I DIFF Residual-voltage monitoring relay · U RES Loss-of-voltage monitoring relay · U LOSS Phase-loss monitoring relay · PH LOSS Frequency monitoring relay · f MON Minimum active-power relay · P LOW Feed-through terminal block · TB FEED Disconnect terminal block · TB DISC Knife-disconnect terminal · TB KNIFE Fuse terminal block · TB FUSE Diode terminal block · TB DIODE Component terminal block · TB COMP Multilevel terminal block · TB LEVEL Multi-conductor terminal block · TB MULTI Protective-earth terminal block · TB PE Sensor terminal block · TB SENSOR Actuator terminal block · TB ACT Plug-in terminal block · TB PLUG High-current terminal block · TB POWER Terminal jumper bridge · TB BRIDGE Plug and socket connector pair · PLUG SOCKET Connector plug half · PLUG Connector socket half · SOCKET Wire splice · SPLICE Earth connection · EARTH Functional earth · FE Protective equipotential bonding · BOND PE Functional equipotential bonding · BOND FE Surge arrester · SA Gas-discharge protection tube · GDT Spark-gap protective element · SPARK GAP Variable resistor · R VAR Potentiometer · POT Light-dependent resistor · LDR Heating element · HEATER RC network · RC Varistor · VDR Current-measuring shunt · SHUNT Electrolytic capacitor · C ELEC Feedthrough capacitor · C FEED Adjustable capacitor · C ADJ Three-phase power-factor capacitor · CAP 3PH Reactor · L Iron-core reactor · L IRON Gapped-core inductor · L GAP Adjustable-core inductor · L ADJ Diode · D Photodiode · PD Zener diode · ZD DIAC · DIAC Single-phase bridge rectifier · BR 1PH Three-phase bridge rectifier · BR 3PH Silicon-controlled rectifier · SCR Gate-turn-off thyristor · GTO TRIAC · TRIAC Bidirectional breakdown diode · TVS BI Single-phase AC motor · M 1PH AC Single-phase motor with fan · M 1PH FAN Three-phase AC motor · M 3PH Three-phase motor with fan · M 3PH FAN Wound-rotor induction motor · M WR Three-phase synchronous motor · M 3PH SYNC DC motor · M DC Permanent-magnet DC motor · M DC PM Series-excited DC motor · M DC SERIES Separately excited DC motor · M DC SEP DC generator · G DC Compound-excited DC generator · G DC COMP Three-phase synchronous generator · G 3PH SYNC Permanent-magnet synchronous generator · G 3PH PM AC-to-DC power supply · PSU AC-DC DC-to-DC converter · DC-DC DC-to-AC inverter · INV DC-AC DC uninterruptible power supply · UPS DC AC uninterruptible power supply · UPS AC Capacitor buffer module · BUFFER CAP Redundant power-supply decoupling module · PSU RED Analog current signal isolator · ISO I-I Temperature measuring transducer · TEMP TX Photovoltaic inverter · PV INV Single-phase AC source · AC 1PH Three-phase AC source · AC 3PH Photovoltaic generator · PV GEN Solar generating station · SOLAR STN Wind generating station · WIND STN Substation · SUBSTATION Converter substation · CONV STN Generic electrical load · LOAD Transformer-fed indicator lamp · LAMP TX Push-to-test indicator lamp · LAMP TEST LED indicator lamp · LAMP LED Flashing indicator lamp · LAMP FLASH Flashing beacon · BEACON FLASH Rotating beacon · BEACON ROT PLC digital input · DI PLC relay output · DO RELAY PLC transistor output · DO TRANS PLC analog input · AI PLC analog output · AO PLC temperature input · TI Capacitor voltage transformer · CVT / CCVT ANSI/IEEE circuit breaker symbol · CB ANSI/IEEE thermal circuit breaker symbol · CB TH ANSI/IEEE thermal-magnetic circuit breaker symbol · CB TM ANSI/IEEE current-limiting circuit breaker symbol · CB LIM ANSI/IEEE circuit breaker with undervoltage release symbol · CB UV ANSI/IEEE circuit breaker with electronic trip unit symbol · CB ETU ANSI/IEEE disconnector symbol · Isolator ANSI/IEEE switch-disconnector symbol · SD ANSI/IEEE lockable disconnector symbol · DS LOCK ANSI/IEEE lockable switch-disconnector symbol · SD LOCK ANSI/IEEE fused switch symbol · SW FUSE ANSI/IEEE fuse symbol · FU ANSI/IEEE fuse-switch symbol · FUSE SW ANSI/IEEE current transformer symbol · CT ANSI/IEEE current transformer with two secondaries symbol · CT 2SEC ANSI/IEEE tapped-secondary current transformer symbol · CT TAP ANSI/IEEE voltage transformer symbol · VT / PT ANSI/IEEE power transformer symbol · TX ANSI/IEEE electrostatically screened transformer symbol · TX SCREEN ANSI/IEEE three-winding transformer symbol · TX 3W ANSI/IEEE adjustable-ratio transformer symbol · TX ADJ ANSI/IEEE single-phase autotransformer symbol · AT 1PH ANSI/IEEE reactor symbol · L ANSI/IEEE iron-core reactor symbol · L IRON ANSI/IEEE gapped-core inductor symbol · L GAP ANSI/IEEE adjustable-core inductor symbol · L ADJ ANSI/IEEE normally open contact symbol · NO ANSI/IEEE normally closed contact symbol · NC ANSI/IEEE changeover contact symbol · CO ANSI/IEEE relay coil symbol · Coil ANSI/IEEE mechanically latched relay coil symbol · K LATCH ANSI/IEEE relay reset coil symbol · K RESET ANSI/IEEE polarised relay coil symbol · K POL ANSI/IEEE ac relay coil symbol · K AC ANSI/IEEE relay coil with diode suppression symbol · K DIODE ANSI/IEEE relay coil with rc suppression symbol · K RC ANSI/IEEE on-delay timer relay symbol · TON ANSI/IEEE off-delay timer relay symbol · TOFF ANSI/IEEE maintained normally-open contact symbol · NO HOLD ANSI/IEEE maintained normally-closed contact symbol · NC HOLD ANSI/IEEE early-make normally-open contact symbol · NO EARLY ANSI/IEEE late-make normally-open contact symbol · NO LATE ANSI/IEEE early-break normally-closed contact symbol · NC EARLY ANSI/IEEE late-break normally-closed contact symbol · NC LATE ANSI/IEEE motor overload trip nc contact symbol · OL NC ANSI/IEEE motor overload alarm no contact symbol · OL NO ANSI/IEEE normally open pushbutton symbol · PB NO ANSI/IEEE normally closed pushbutton symbol · PB NC ANSI/IEEE illuminated normally-open pushbutton symbol · PB NO LAMP ANSI/IEEE illuminated normally-closed pushbutton symbol · PB NC LAMP ANSI/IEEE maintained normally-open pushbutton symbol · PB NO HOLD ANSI/IEEE maintained normally-closed pushbutton symbol · PB NC HOLD ANSI/IEEE selector switch symbol · SS ANSI/IEEE three-position maintained selector symbol · SEL 3 HOLD ANSI/IEEE three-position centre-return selector symbol · SEL 3 CRET ANSI/IEEE three-position key selector symbol · KEY SEL 3 ANSI/IEEE four-position maintained selector symbol · SEL 4 HOLD ANSI/IEEE four-position key selector symbol · KEY SEL 4 ANSI/IEEE normally-open limit switch symbol · LS NO ANSI/IEEE normally-closed limit switch symbol · LS NC ANSI/IEEE roller-operated limit switch symbol · LS ROLLER ANSI/IEEE pressure switch no symbol · PS NO ANSI/IEEE pressure switch nc symbol · PS NC ANSI/IEEE temperature switch no symbol · TS NO ANSI/IEEE temperature switch nc symbol · TS NC ANSI/IEEE float level switch no symbol · LS FLOAT NO ANSI/IEEE float level switch nc symbol · LS FLOAT NC ANSI/IEEE liquid flow switch symbol · FS LIQ ANSI/IEEE terminal connection symbol · Terminal ANSI/IEEE numbered terminal symbol · TERM 1 ANSI/IEEE plug and socket connector pair symbol · PLUG SOCKET ANSI/IEEE connector plug half symbol · PLUG ANSI/IEEE connector socket half symbol · SOCKET ANSI/IEEE wire splice symbol · SPLICE ANSI/IEEE protective earth symbol · PE ANSI/IEEE functional earth symbol · FE ANSI/IEEE resistor symbol · R ANSI/IEEE variable resistor symbol · R VAR ANSI/IEEE potentiometer symbol · POT ANSI/IEEE light-dependent resistor symbol · LDR ANSI/IEEE heating element symbol · HEATER ANSI/IEEE varistor symbol · VDR ANSI/IEEE current-measuring shunt symbol · SHUNT ANSI/IEEE capacitor symbol · C ANSI/IEEE electrolytic capacitor symbol · C ELEC ANSI/IEEE feedthrough capacitor symbol · C FEED ANSI/IEEE adjustable capacitor symbol · C ADJ ANSI/IEEE diode symbol · D ANSI/IEEE photodiode symbol · PD ANSI/IEEE zener diode symbol · ZD ANSI/IEEE single-phase bridge rectifier symbol · BR 1PH ANSI/IEEE silicon-controlled rectifier symbol · SCR ANSI/IEEE triac symbol · TRIAC ANSI/IEEE voltmeter symbol · V ANSI/IEEE ammeter symbol · A ANSI/IEEE power-factor meter symbol · PF ANSI/IEEE frequency meter symbol · Hz ANSI/IEEE recording wattmeter symbol · W REC ANSI/IEEE reactive-power meter symbol · var ANSI/IEEE synchronoscope symbol · SYNC SCOPE ANSI/IEEE running-hours meter symbol · HOURS ANSI/IEEE single-phase ac motor symbol · M 1PH AC ANSI/IEEE three-phase ac motor symbol · M 3PH ANSI/IEEE wound-rotor induction motor symbol · M WR ANSI/IEEE dc motor symbol · M DC ANSI/IEEE permanent-magnet dc motor symbol · M DC PM ANSI/IEEE three-phase synchronous generator symbol · G 3PH SYNC ANSI/IEEE dc generator symbol · G DC ANSI/IEEE indicator lamp symbol · Lamp ANSI/IEEE transformer-fed indicator lamp symbol · LAMP TX ANSI/IEEE push-to-test indicator lamp symbol · LAMP TEST ANSI/IEEE led indicator lamp symbol · LAMP LED ANSI/IEEE on-delay normally-open contact symbol · TON NO ANSI/IEEE on-delay normally-closed contact symbol · TON NC ANSI/IEEE off-delay normally-open contact symbol · TOFF NO ANSI/IEEE off-delay normally-closed contact symbol · TOFF NC Positive-operation direction qualifier · Q070109 Manual-operation qualifier · Q021301 Protected-access manual-operation qualifier · Q021302 Pushbutton-operation qualifier · Q021305 Emergency-operation qualifier · Q021308 Rotary-operation qualifier · Q021304 Key-operation qualifier · Q021313 Foot-operation qualifier · Q021310 Lever-operation qualifier · Q021311 Crank-operation qualifier · Q021214 Handwheel-operation qualifier · Q021309 Liquid-level actuation qualifier · Q021401 Event-count actuation qualifier · Q021402 Liquid-flow actuation qualifier · Q021403 Gas-flow actuation qualifier · Q021404 Motor-operation qualifier · Q021326 Timed-operation qualifier · Q021327 Roller-operation qualifier · Q021315 Cam-operation qualifier · Q021316 Cam-profile indication · Q021317 Switch-position function qualifier · Q070106 Isolation-function qualifier · Q070103 Switch-disconnector function qualifier · Q070104 Circuit-breaker function qualifier · Q070102 Power-contactor function qualifier · Q070101 Automatic-trip qualifier · Q070105 Spring-return qualifier · Q070107 Maintained-position qualifier · Q070108 One-way linear-motion qualifier · Q020401R Two-way linear-motion qualifier · Q020402 Transition indication · Q101101 One-way rotary-motion qualifier · Q020403 Two-way rotary-motion qualifier · Q020404 Limited two-way rotary-motion qualifier · Q020405 Unidirectional propagation qualifier · Q020501 Simultaneous bidirectional propagation qualifier · Q020502 Alternating bidirectional propagation qualifier · Q020503 Signal-transmission qualifier · Q020504 Signal-reception qualifier · Q020505 Outbound-energy-flow qualifier · Q020506 Inbound-energy-flow qualifier · Q020507 Bidirectional-energy-flow qualifier · Q020508 Thermal-effect qualifier · Q020801 Magnetic-effect qualifier · Q020802 Magnetostrictive-effect qualifier · Q020803 Magnetic-field-effect qualifier · Q020804 Non-ionising radiation qualifier · Q020901 Ionising-radiation qualifier · Q020903 Presumed-fault-location indication · Q021701 Insulation-failure indication · Q021702 Two-phase winding connection · Q060201 Partial-V winding connection · Q060202 Four-phase winding with accessible connection · Q060203 Three-phase T winding connection · Q060204 Six-phase double-delta winding connection · Q060210 Six-phase polygon winding connection · Q060211 Six-phase star winding connection · Q060212 Six-phase double-zigzag winding connection · Q060213 Direct-current supply qualifier · Q020201 Alternating-current supply qualifier · Q020204 Rectified-current with AC component qualifier · Q020212 Automatic mechanical-return indication · Q021207 Mechanical stop-latch indication · Q021208 Mechanical stop latch in neutral state · Q021209 Mechanical stop latch in engaged state · Q021210 Mechanical interlock between devices · Q021211 Two-way latching device · Q1020603 Manually released latching device · Q1020604 Key-controlled two-way latching device · Q1029603 Mechanical clutch connection · Q021216 Disconnected mechanical coupling · Q021217 Engaged mechanical coupling · Q021218 Mechanical gear connection · Q021223 Thermocouple with terminal board · HTC1LTB Pyrometer indication · HIN1P25 Clock indication · HIN1P29 Minute-pulse clock contact · HIN1P33 Pressure-to-current converter · HIN1B10 Single-phase AC-to-DC current converter · HIN1G1 Tachometric dynamo · HIN1B11 Impulse tachometric transducer · HIN1B12 Optical tachometric transducer · HIN1B13 Audible bell · HAN1B Audible buzzer · HAN1Z Audible siren · HAN1S Loudspeaker annunciation · HAN1B7 Combined loudspeaker and microphone · HAN1B8 Microphone input · HAN1B9 Solenoid valve actuator · HSV1 Solenoid closing function for an open valve · HSV1Y1 Electromagnetic brake actuator · HSV1Y4 Solenoid-valve NO auxiliary contact · HSV21 Solenoid-valve NC auxiliary contact · HSV22 Ultrasonic proximity switch · HPX1U Ultrasonic NO switching output · HPX11U Ultrasonic NC switching output · HPX12U Three-wire ultrasonic sensor · HPX11U3 Touch-sensitive switch · HPX1TS Touch-switch NO output · HPX11TS Touch-switch NC output · HPX12TS Three-wire touch-sensitive switch · HPX11TS3 Phase-to-phase voltmeter selector · HSW1S90 Phase-to-neutral voltmeter selector · HSW1S91 Combined line and phase voltmeter selector · HSW1S92 Two-network voltage measurement selector · HSW1S93 Three-point current measurement selector · HSW1S94 Four-point current measurement selector · HSW1S95 Latched pull-cord switch · HPC11L Latched foot-operated switch · HFT11L Latched lever-operated switch · HPB11LSL Three-phase motor with four connections · HMO14 Three-phase induction motor with series excitation · HMO1M3 Star-stator wound-rotor motor with rotor starter · HMO1M5 Six-pole asynchronous motor · HMO1M11 Single-phase series-connected AC motor · HMO1M10 Single-phase synchronous motor · HMO1M16 Permanent-magnet linear DC motor · HMO1M14 Permanent-magnet stepping motor · HMO1M15 Shunt-excited DC motor · HMO1M8 Resistor with disconnecting slider · HVR1R5 Carbon-disc variable resistor · HVR1R8 Magnetoresistive element · HVR1S00689 Differential capacitor · HCA1_S00573 Preset-adjustable capacitor · HCA1_S00575 Split adjustable capacitor · HCA1_S00579 Cable identification marker · HW01 Additional cable-core marker · HW02 Twisted-pair indication · HT0_TW Single power receptacle · HCN1RSGL Duplex power receptacle · HCN1RDUP Generic device boundary · HDV1T6 Standalone source cross-reference · HA2S1_REF Standalone destination cross-reference · HA2D1_REF Reference-only wire arrow · HA1X1 One-line connector representation · HC01PJ_1- One-line terminal representation · HT0001_1- One-line cable identification · HW01_1- One-line bus tap · HDV1_BT_1- One-line power receptacle · HC01WR_1- Connector retaining wire identity · HC01PJ Connector changing wire identity · HCN1PJ Terminal carrying wire identification · HT0W02 Terminal with wire-number transition · HT1002 Conductor connection junction · JUNCTION Unconnected conductor crossing · CROSSING Three-phase conductor group · 3~ Dy5 transformer connection reference · Dy5 Dd6 transformer connection reference · Dd6 Yd5 transformer connection reference · Yd5 Yy6 transformer connection reference · Yy6 Yd11 transformer connection reference · Yd11 Dy11 transformer connection reference · Dy11 Dz0 transformer connection reference · Dz0 Yz5 transformer connection reference · Yz5 Dz6 transformer connection reference · Dz6 Yz11 transformer connection reference · Yz11 Schottky diode · SBD Unidirectional TVS diode · TVS Light-emitting diode · LED Varactor diode · VAR PIN diode · PIN NPN bipolar transistor · NPN PNP bipolar transistor · PNP NPN Darlington transistor · NPN-DAR PNP Darlington transistor · PNP-DAR N-channel JFET · N-JFET P-channel JFET · P-JFET N-channel enhancement MOSFET · N-MOS P-channel enhancement MOSFET · P-MOS N-channel depletion MOSFET · N-DMOS Insulated-gate bipolar transistor · IGBT MOSFET body diode · BODY-D GaN enhancement-mode HEMT · E-HEMT Integrated gate-commutated thyristor · IGCT NPN phototransistor · PHOTO-NPN Phototransistor optocoupler · OPTO-TR Photodiode optocoupler · OPTO-PD Phototriac optocoupler · OPTO-TRIAC Photovoltaic MOSFET driver · PV-DRV Capacitive digital isolator · DIG-ISO Isolated gate driver · ISO-GD Low-side gate driver · LS-GD High-side gate driver · HS-GD Bootstrap gate-drive supply · BOOT Ideal-diode controller · IDEAL-D Hot-swap controller · HOT-SWAP Electronic fuse IC · EFUSE Half-bridge power module · HB-MOD Three-phase sixpack power module · 6-PACK AND gate · AND OR gate · OR NAND gate · NAND NOR gate · NOR Exclusive-OR gate · XOR Exclusive-NOR gate · XNOR Logic inverter · NOT Non-inverting logic buffer · BUF Three-state logic buffer · 3STATE Schmitt-trigger inverter · SCHMITT-NOT Schmitt-trigger buffer · SCHMITT Positive-edge D flip-flop · D-FF Negative-edge JK flip-flop · JK-FF Set-reset latch · SR-LATCH Transparent D latch · D-LATCH Serial-in parallel-out register · SIPO Parallel-in serial-out register · PISO Shift register with output latch · SHIFT-LATCH Ripple binary counter · CTR-RIP Synchronous binary counter · CTR-SYNC Decoded decade counter · DECADE Retriggerable monostable · ONE-SHOT Binary decoder / demultiplexer · DEC Priority encoder · ENC-PRI Digital multiplexer · MUX Digital magnitude comparator · MAG-COMP Binary full adder · ADD Logic bus transceiver · BUS-TR Logic voltage-level translator · LEVEL Open-collector buffer · OC-BUF Parity generator / checker · PARITY Phase-locked loop · PLL Voltage-controlled oscillator · VCO Clock generator · CLK-GEN Watchdog timer · WDT Operational amplifier · OP-AMP Voltage comparator · COMP Instrumentation amplifier · INA Difference amplifier · DIFF-AMP Fully differential amplifier · FDA Current-sense amplifier · CSA Isolation amplifier · ISO-AMP Operational transconductance amplifier · OTA Analogue multiplier · MULT Analogue bilateral switch · A-SW Analogue multiplexer · A-MUX Sample-and-hold amplifier · S/H Analogue-to-digital converter · ADC Digital-to-analogue converter · DAC Series voltage reference · VREF-S Shunt voltage reference · VREF-H Precision rectifier · PREC-RECT RMS-to-DC converter · RMS-DC Voltage / frequency converter · V/F Inverting amplifier circuit · INV-AMP Non-inverting amplifier circuit · NI-AMP Op-amp integrator · INTEGRATOR Op-amp differentiator · DIFFERENTIATOR Active low-pass filter · LPF Active high-pass filter · HPF Active band-pass filter · BPF Active notch filter · NOTCH Transimpedance amplifier · TIA Buck converter topology · BUCK Boost converter topology · BOOST Inverting buck-boost topology · INV-BB Four-switch buck-boost topology · 4SW-BB SEPIC converter topology · SEPIC Cuk converter topology · CUK Zeta converter topology · ZETA Flyback converter topology · FLYBACK Forward converter topology · FORWARD Active-clamp forward topology · ACF Push-pull converter topology · PUSH-PULL Half-bridge DC converter topology · HB-DC Full-bridge DC converter topology · FB-DC Phase-shifted full-bridge topology · PSFB LLC resonant converter topology · LLC Dual-active-bridge topology · DAB Single-phase voltage-source inverter · 1PH-VSI Three-phase voltage-source inverter · 3PH-VSI Neutral-point-clamped inverter · NPC Active front-end rectifier · AFE Synchronism check · 25 Undervoltage · 27 Directional power · 32 Current unbalance / negative sequence · 46 Thermal protection · 49 Instantaneous overcurrent · 50 Time overcurrent · 51 AC circuit breaker · 52 Overvoltage · 59 Directional overcurrent · 67 AC autoreclosing · 79 Frequency protection · 81 Lockout · 86 Differential protection · 87 Line switch · 89 Master element · 1 Time-delay starting or closing relay · 2 Checking or interlocking relay · 3 Master contactor · 4 Stopping device · 5 Starting circuit breaker · 6 Rate-of-change relay · 7 Control power disconnecting device · 8 Reversing device · 9 Unit sequence switch · 10 Multifunction device · 11 Overspeed device · 12 Synchronous-speed device · 13 Underspeed device · 14 Speed or frequency matching device · 15 Data communications device · 16 Shunting or discharge switch · 17 Accelerating or decelerating device · 18 Starting-to-running transition contactor · 19 Electrically operated valve · 20 Distance protection · 21 Equalizer circuit breaker · 22 Temperature control device · 23 Overexcitation protection · 24 Apparatus thermal device · 26 Flame detector · 28 Isolating contactor · 29 Annunciator relay · 30 Separate excitation device · 31 Position switch · 33 Master sequence device · 34 Brush-operating or slip-ring short-circuiting device · 35 Polarity device · 36 Undercurrent or underpower protection · 37 Bearing protective device · 38 Mechanical condition monitor · 39 Field or loss-of-excitation protection · 40 Field circuit breaker · 41 Running circuit breaker · 42 Manual transfer or selector device · 43 Unit sequence starting relay · 44 Atmospheric condition monitor · 45 Phase-sequence or voltage-balance protection · 47 Incomplete-sequence relay · 48 Exciter or DC generator relay · 53 Turning-gear engaging device · 54 Power factor protection · 55 Field application relay · 56 Short-circuiting or grounding device · 57 Rectification failure relay · 58 Voltage or current balance relay · 60 Density switch or sensor · 61 Time-delay stopping or opening relay · 62 Pressure switch or relay · 63 Ground detector protection · 64 Governor · 65 Notching or jogging device · 66 Blocking or out-of-step supervision · 68 Permissive control device · 69 Rheostat · 70 Level switch or relay · 71 DC circuit breaker · 72 Load-resistor contactor · 73 Alarm relay · 74 Position-changing mechanism · 75 DC overcurrent relay · 76 Telemetering device · 77 Phase-angle or out-of-step protection · 78 Flow switch or relay · 80 DC load-measuring reclosing relay · 82 Automatic selective control or transfer relay · 83 Operating mechanism · 84 Pilot or carrier receiver relay · 85 Auxiliary motor or motor-generator · 88 Regulating device · 90 Voltage directional relay · 91 Voltage and power directional relay · 92 Field-changing contactor · 93 Tripping or trip-free relay · 94 Phase distance protection · 21P Ground distance protection · 21G Admittance-based earth-fault protection · 21YN Auxiliary-input undervoltage protection · 27A Main-input undervoltage protection · 27M Reactive-power undervoltage protection · 27Q Low-voltage ride-through supervision · 27T Wattmetric earth-fault protection · 32N Directional reactive-power protection · 32V Reverse-power protection · 32R Underpower protection · 32U Generator current-unbalance protection · 46G Phase-discontinuity protection · 46PD RTD-based thermal protection · 49R Motor thermal-model protection · 49M Instantaneous phase overcurrent · 50P Instantaneous neutral overcurrent · 50N Instantaneous ground overcurrent · 50G Instantaneous negative-sequence overcurrent · 50Q Calculated residual instantaneous overcurrent · 50R Measured ground instantaneous overcurrent · 50X Circuit-breaker failure protection · 50BF Motor jam or stall protection · 50J Time phase-overcurrent protection · 51P Time neutral-overcurrent protection · 51N Time ground-overcurrent protection · 51G Time negative-sequence overcurrent · 51Q Calculated residual time-overcurrent · 51R Measured ground time-overcurrent · 51X Voltage-dependent overcurrent · 51V Apparent power-factor supervision · 55A Displacement power-factor supervision · 55D Residual or neutral overvoltage · 59N Negative-sequence overvoltage · 59Q Auxiliary-input overvoltage · 59A Main-input overvoltage · 59M Field ground-fault protection · 64F Stator ground-fault protection · 64G Directional phase-overcurrent · 67P Directional neutral-overcurrent · 67N Directional ground-overcurrent · 67G Directional negative-sequence overcurrent · 67Q Calculated residual directional overcurrent · 67R Measured ground directional overcurrent · 67X Multifrequency admittance earth-fault protection · 67YN Transient or intermittent earth-fault protection · 67NIEF Trip-coil monitoring · 74TCM Voltage vector-shift protection · 78VS Underfrequency protection · 81U Overfrequency protection · 81O Rate-of-change-of-frequency protection · 81R Transformer differential protection · 87T Busbar differential protection · 87B Generator differential protection · 87G Motor differential protection · 87M Line current differential protection · 87L Neutral differential protection · 87N Negative-sequence differential protection · 87Q Restrained current differential protection · 87R Unrestrained high-set differential protection · 87H Restricted ground differential protection · 87GD Switchgear panel · Panel Switchboard · Board Ring main unit · RMU Transformer envelope · Transformer GA Battery storage cabinet · BESS cabinet Power conversion cabinet · PCS cabinet Generator package · Genset GA Transfer-switch assembly · ATS Control / marshalling cabinet · Control GA Cable ladder / tray · Cable support Busbar trunking · Busway Mounting plate · Plate Terminal strip assembly · Terminal strip Air circuit breaker · ACB Moulded-case circuit breaker · MCCB Miniature circuit breaker · MCB Residual-current circuit breaker · RCCB Residual-current breaker with overcurrent protection · RCBO DC circuit breaker · GA Motor-protection circuit breaker · MPCB Switch disconnector · GA Fuse-switch disconnector · GA Fuse holder · GA Power contactor · GA Reversing contactor assembly · GA Star-delta starter assembly · GA Thermal overload relay · GA Electronic motor overload relay · GA Soft starter · GA Variable-frequency drive · VFD Drive braking resistor · GA AC line reactor · GA Control transformer · GA Dry-type transformer enclosure · GA Oil-filled transformer installation · GA Neutral earthing resistor cabinet · NER Power-factor-correction capacitor bank · GA Active harmonic filter cabinet · GA Surge protective device assembly · SPD DIN-rail AC/DC power supply · GA DIN-rail DC/DC converter · DC DC redundancy module · GA DC buffer module · GA DC UPS module · GA Battery charger · DC AC UPS cabinet · GA UPS maintenance bypass panel · GA Station DC battery rack · GA PLC CPU module · GA PLC power module · GA Digital input module · GA Digital output module · GA Analogue input module · GA Analogue output module · GA Remote I/O station · GA HMI touchscreen · GA Industrial panel PC · GA Industrial Ethernet switch · GA Industrial VPN router · GA Fibre-optic patch panel · GA Communication gateway · GA Interface relay module · GA Relay socket · GA Timer relay · GA Safety relay module · GA Signal conditioner · GA Terminal marshalling interface · GA Feed-through terminal block · GA Protective-earth terminal block · GA Multi-level terminal block · GA Fuse terminal block · GA Disconnect terminal block · GA CT shorting test terminal · GA Distribution terminal block · GA Pluggable terminal connector · GA Terminal end stop · GA Terminal marker strip · GA DIN mounting rail · GA Slotted wiring duct · GA Cable gland · GA Cable-entry frame · GA Bulkhead connector · GA Cable cleat · GA Perforated cable tray · GA Wire-mesh cable basket · GA Cable-tray horizontal bend · GA Cable-tray vertical riser · GA Cable support bracket · GA Cable trench · GA Cable pit · GA Cable duct bank · GA Earth bar · GA Neutral bar · GA Flexible busbar connection · GA Rigid busbar assembly · GA Busbar support insulator · GA Busway tap-off unit · GA LV incomer compartment · GA LV feeder compartment · GA Bus-coupler compartment · GA Cable termination compartment · GA Busbar compartment · GA Metering compartment · GA Motor control centre lineup · GA Withdrawable motor feeder unit · GA MV vacuum circuit-breaker truck · GA Switchgear arc exhaust plenum · GA Protection relay panel · GA Panel power meter · GA Energy submeter · GA Window current transformer · GA Split-core current transformer · GA Voltage transformer assembly · VT Wall-mounted junction enclosure · GA Floor-standing enclosure · GA Enclosure plinth · GA Enclosure gland plate · GA Enclosure door swing envelope · GA Equipment maintenance envelope · GA Equipment removal route · GA Switchroom egress path · GA Enclosure anti-condensation heater · GA Enclosure thermostat · GA Enclosure hygrostat · GA Enclosure filter fan · GA Enclosure air conditioner · GA Enclosure air-to-air heat exchanger · GA Switchroom supply fan · GA Switchroom exhaust fan · GA Ventilation intake louver · GA Motorised ventilation damper · GA Backdraft damper · GA Fire damper · GA Smoke-control damper · GA Generator day tank · GA Generator bulk fuel tank · GA Generator fuel transfer pump · GA Generator fuel bund · GA Generator exhaust silencer · GA Generator exhaust flexible connection · GA Generator exhaust stack · GA Generator radiator discharge duct · GA Generator remote radiator · GA Generator vibration isolator · GA Generator acoustic canopy · GA Generator coolant heater · GA Generator starting battery · GA Generator paralleling controller · GA PV string combiner box · GA PV inverter cabinet · GA PV DC isolator enclosure · GA MPPT solar charge controller · GA Battery inverter-charger · GA Battery management system module · BMS Battery DC disconnect assembly · GA Battery precharge assembly · DC Battery DC bus distribution module · DC Battery current shunt · DC Energy-management controller · EMS Outdoor energy-storage container · GA Battery cooling unit · GA Battery fire-system interface panel · GA Smoke detector installation point · GA Fire alarm control panel location · GA Emergency stop station · GA Pilot-light station · GA Selector-switch station · GA Trapped-key interlock assembly · GA Door-mounted pushbutton enclosure · GA Panel service outlet · GA Panel inspection lighting · GA AutomationDirect BRX Series PLC · BRX Series PLC AutomationDirect CLICK PLCs · CLICK PLCs AutomationDirect Productivity1000 PAC · Productivity1000 PAC AutomationDirect Productivity2000 PAC · Productivity2000 PAC AutomationDirect Productivity3000 PAC · Productivity3000 PAC AutomationDirect Terminator Field I/O · Terminator Field I/O AutomationDirect Protos X Field I/O · Protos X Field I/O AutomationDirect ZIPLinks · ZIPLinks AutomationDirect DINnectors · DINnectors AutomationDirect Konnect-It DIN-rail terminals · Konnect-It DIN-rail terminals AutomationDirect C-more Panels · C-more Panels AutomationDirect C-more Micro Graphic Panels · C-more Micro Graphic Panels AutomationDirect GS and DURApulse AC drives · GS and DURApulse AC drives AutomationDirect LR Series line reactors · LR Series line reactors AutomationDirect Bimed cable glands · Bimed cable glands AutomationDirect ZIPport Multi-Wire Connectors · ZIPport Multi-Wire Connectors AutomationDirect ZIPport Panel Interface Connectors · ZIPport Panel Interface Connectors AutomationDirect Gladiator CFS disconnects · Gladiator CFS disconnects AutomationDirect WMZT miniature circuit breakers · WMZT miniature circuit breakers AutomationDirect Edison Class T fuses · Edison Class T fuses AutomationDirect Edison Power Distribution Blocks · Edison Power Distribution Blocks AutomationDirect Stride VPN · Stride VPN AutomationDirect AcuAmp · AcuAmp Fuji Electric BM3 manual motor starters · BM3 manual motor starters Fuji Electric SC contactors and thermal overload relays · GA Fuji Electric SC-NEXT contactors · SC-NEXT contactors Fuji Electric Orange Line / Odyssey contactors · Orange Line / Odyssey contactors Fuji Electric Combination starters · Combination starters Fuji Electric G-Twin Lambda circuit breakers · G-Twin Lambda circuit breakers Fuji Electric G-Twin circuit breakers · G-Twin circuit breakers Fuji Electric EA-UL / SA-UL circuit breakers · EA-UL / SA-UL circuit breakers Fuji Electric EG-UL / SG-UL circuit breakers · EG-UL / SG-UL circuit breakers Fuji Electric SK contactors and relays · SK contactors and relays TDK-Lambda D1SE120-xx-A3 · D1SE120-xx-A3 TDK-Lambda D1SE240-xx-A3 · D1SE240-xx-A3 TDK-Lambda D1SE480-xx-A3 · D1SE480-xx-A3 TDK-Lambda DBM20 · DBM20 TDK-Lambda DRB15 · DRB15 TDK-Lambda DRB30 · DRB30 TDK-Lambda DRB480 · DRB480 TDK-Lambda DRF960 · DRF960 TDK-Lambda DRM40 · DRM40 TDK-Lambda DUSH960-1248-1M · DUSH960-1248-1M PULS QS20.241 · QS20.241 Terasaki TemPower AT air circuit breakers · TemPower AT air circuit breakers Terasaki / NHP TemBreak 1 legacy MCCBs · TemBreak 1 legacy MCCBs Schneider Electric MiCOM protection relays · MiCOM protection relays Invertek Drives Optidrive Eco · Optidrive Eco Schneider Electric MasterPact MTZ · MasterPact MTZ Schneider Electric MasterPacT MTZ Active · MasterPacT MTZ Active Schneider Electric ComPacT NSX, new generation · ComPacT NSX, new generation Schneider Electric ComPacT NSXm, new generation · ComPacT NSXm, new generation Schneider Electric ComPacT for DC networks, new generation · ComPacT for DC networks, new generation Schneider Electric Compact INS/INV · Compact INS/INV Schneider Electric Acti9 iC60 · Acti9 iC60 Schneider Electric Acti9 iC60 RCBO · Acti9 iC60 RCBO Schneider Electric PrismaSeT 6300 · PrismaSeT 6300 Schneider Electric PrismaSeT G · PrismaSeT G Schneider Electric TeSys K contactors · TeSys K contactors Schneider Electric TeSys Giga contactors · TeSys Giga contactors Schneider Electric TeSys Deca overload relays · TeSys Deca overload relays Schneider Electric TeSys GV2, LC · TeSys GV2, LC Schneider Electric PowerLogic PM5000 · PowerLogic PM5000 Schneider Electric PowerLogic PM8000 · PowerLogic PM8000 Schneider Electric PowerLogic P5 protection relays · PowerLogic P5 protection relays Schneider Electric PowerLogic PFC Capacitor Banks · PowerLogic PFC Capacitor Banks Schneider Electric PowerLogic T500 Substation Controller · PowerLogic T500 Substation Controller Schneider Electric TransferPacT · TransferPacT ABB MNS switchgear · MNS switchgear ABB ReliaGear SG switchgear · ReliaGear SG switchgear ABB UniGear switchgear · UniGear switchgear Protection relay IED · GA Medium-voltage switchgear lineup · GA Low-voltage switchgear lineup · GA Source-transfer switch assembly · GA Substation RTU · GA Industrial ventilation fan · GA Lithium battery module · GA DIN-rail adapter accessory · GA Combined fire-smoke damper · GA Victron Energy MultiPlus-II · MultiPlus-II Victron Energy Quattro · Quattro Victron Energy SmartSolar MPPT RS · SmartSolar MPPT RS Victron Energy Cerbo GX · Cerbo GX Victron Energy Lynx Distributor · Lynx Distributor Victron Energy Lynx Smart BMS NG · Lynx Smart BMS NG Victron Energy Lithium NG Batteries · Lithium NG Batteries Victron Energy SmartShunt · SmartShunt Victron Energy Skylla-IP65 · Skylla-IP65 Victron Energy Multi RS Solar · Multi RS Solar Victron Energy MultiPlus-II 2x 120V · MultiPlus-II 2x 120V Victron Energy DIN35 adapter · DIN35 adapter DEIF iE 250 controllers · iE 250 controllers Westermo PS2-60 · PS2-60 Westermo Lynx 5612-E-F4G-T8G-LV · Lynx 5612-E-F4G-T8G-LV Dagartech BGPSW 15 ST · BGPSW 15 ST Dagartech DGB 415 ST · DGB 415 ST Greenheck QEI inline fan · QEI inline fan Greenheck QEID inline fan · QEID inline fan Greenheck TBI-FS inline fan · TBI-FS inline fan Greenheck VAB fan · VAB fan Greenheck VAD fan · VAD fan Greenheck USF fan · USF fan Greenheck APH plenum fan · APH plenum fan Greenheck SBE wall fan · SBE wall fan Greenheck SBS wall fan · SBS wall fan Greenheck SE wall fan · SE wall fan Greenheck ESD-435 louver · ESD-435 louver Greenheck ESD-635 louver · ESD-635 louver Greenheck AFL-501 louver · AFL-501 louver Greenheck FSD-311 damper · FSD-311 damper Greenheck FSD-211 damper · FSD-211 damper Greenheck FD-150 damper · FD-150 damper Power cable joint · CABLE JOINT Power quality meter · PQM Compare withCurrent transformer · CT Voltage transformer · VT / PT Circuit breaker · CB Disconnector · Isolator Load-break switch · LBS Earthing switch · ES Fuse · FU Busbar · Bus Normally open contact · NO Normally closed contact · NC Changeover contact · CO Relay coil · Coil Contactor · KM Normally open pushbutton · PB NO Normally closed pushbutton · PB NC Emergency-stop operator · E-stop Selector switch · SS Indicator lamp · Lamp Terminal connection · Terminal CT test terminal · CT test Power transformer · TX Generator · GEN Three-phase motor · M PLC input / output · PLC I/O Capacitor · C Resistor · R Protective earth · PE Battery · BAT Power converter / inverter · PCS Single-pole circuit breaker · CB 1P Thermal circuit breaker · CB TH Thermal-magnetic circuit breaker · CB TM Current-limiting circuit breaker · CB LIM Residual-current circuit breaker · RCCB Residual-current breaker with overcurrent protection · RCBO Circuit breaker with undervoltage release · CB UV Circuit breaker with electronic trip unit · CB ETU Miniature circuit breaker · MCB Moulded-case circuit breaker · MCCB Air circuit breaker · ACB Additional circuit-breaker pole · CB POLE Switch-disconnector · SD Lockable disconnector · DS LOCK Lockable switch-disconnector · SD LOCK Three-position disconnector · DS 3POS Semiconductor power switch · SSW Unidirectional semiconductor power switch · SSW UNI Two-pole power switch · SW 2P Disconnector auxiliary NO contact · DS AUX NO Disconnector auxiliary NC contact · DS AUX NC Fused switch · SW FUSE Fuse-switch · FUSE SW Additional fused-switch pole · FUSE POLE General-purpose full-range fuse · gG Motor short-circuit fuse · aM Motor full-range fuse · gM Current transformer with two secondaries · CT 2SEC Tapped-secondary current transformer · CT TAP Current transformer with primary conductor indication · CT PRI Core-balance current transformer · CBCT Residual connection of phase CTs · CT RES Single-phase two-winding transformer · TX 1PH Electrostatically screened transformer · TX SCREEN Three-winding transformer · TX 3W Adjustable-ratio transformer · TX ADJ Single-phase autotransformer · AT 1PH Three-phase star autotransformer · AT 3PH Y Star-delta transformer · TX Y-D Delta-star transformer · TX D-Y Delta-delta transformer · TX D-D Star-star transformer · TX Y-Y Star-zigzag transformer · TX Y-Z Star-star-delta three-winding transformer · TX Y-Y-D Delta winding connection · DELTA Open-delta winding connection · OPEN D Star winding connection · STAR Y Star winding with accessible neutral · Y N Zigzag winding connection · ZIGZAG Mechanically latched relay coil · K LATCH Relay reset coil · K RESET Solid-state relay · SSR Polarised relay coil · K POL AC relay coil · K AC High-speed relay · K FAST Measuring relay · K MEAS Relay coil with diode suppression · K DIODE Relay coil with diode and LED · K D LED Relay coil with capacitor suppression · K CAP Relay coil with RC suppression · K RC Counter relay with manual reset · COUNT MAN Counter relay with electrical reset · COUNT ELEC Non-resettable counter relay · COUNT TOTAL On-delay timer relay · TON Off-delay timer relay · TOFF On-delay normally-open contact · TON NO On-delay normally-closed contact · TON NC Off-delay normally-open contact · TOFF NO Off-delay normally-closed contact · TOFF NC Maintained normally-open contact · NO HOLD Maintained normally-closed contact · NC HOLD Manually unlatched NO contact · NO UNLATCH Manually unlatched NC contact · NC UNLATCH Early-make normally-open contact · NO EARLY Late-make normally-open contact · NO LATE Early-break normally-closed contact · NC EARLY Late-break normally-closed contact · NC LATE Make-before-break changeover contact · MBB Motor overload trip NC contact · OL NC Motor overload alarm NO contact · OL NO Illuminated normally-open pushbutton · PB NO LAMP Illuminated normally-closed pushbutton · PB NC LAMP Maintained normally-open pushbutton · PB NO HOLD Maintained normally-closed pushbutton · PB NC HOLD Key-operated normally-open switch · KEY NO Key-operated normally-closed switch · KEY NC Latched key-operated switch · KEY HOLD Pull-cord switch · PULL CORD Foot-operated switch · FOOT Lever-operated switch · LEVER Three-position maintained selector · SEL 3 HOLD Three-position selector returning from left · SEL 3 LRET Three-position selector returning from right · SEL 3 RRET Three-position centre-return selector · SEL 3 CRET Three-position key selector · KEY SEL 3 Four-position maintained selector · SEL 4 HOLD Four-position key selector · KEY SEL 4 Normally-open limit switch · LS NO Normally-closed limit switch · LS NC Roller-operated limit switch · LS ROLLER Cam-operated limit switch · LS CAM Pressure switch NO · PS NO Pressure switch NC · PS NC Temperature switch NO · TS NO Temperature switch NC · TS NC Self-operating thermal switch · TS SELF Float level switch NO · LS FLOAT NO Float level switch NC · LS FLOAT NC Liquid flow switch · FS LIQ Gas flow switch · FS GAS Inductive proximity switch · PROX IND Three-wire inductive proximity switch · PROX IND 3W Capacitive proximity switch · PROX CAP Magnetic proximity switch · PROX MAG Photoelectric emitter-receiver switch · PHOTO Thermocouple · TC Resistance temperature detector · RTD Voltmeter · V Ammeter · A Power-factor meter · PF Phase-angle meter · PHASE Frequency meter · Hz Temperature indicator · TEMP Tachometer · RPM Running-hours meter · HOURS Ampere-hour meter · Ah Recording wattmeter · W REC Reactive-power meter · var Synchronoscope · SYNC SCOPE Active-power indicator · kW Differential voltmeter · DELTA V Active-energy meter · kWh Reactive-energy meter · kvarh Maximum-current monitoring relay · I HIGH Minimum-current monitoring relay · I LOW Current window monitoring relay · I WINDOW Differential-current measuring relay · I DIFF Residual-voltage monitoring relay · U RES Loss-of-voltage monitoring relay · U LOSS Phase-loss monitoring relay · PH LOSS Frequency monitoring relay · f MON Minimum active-power relay · P LOW Feed-through terminal block · TB FEED Disconnect terminal block · TB DISC Knife-disconnect terminal · TB KNIFE Fuse terminal block · TB FUSE Diode terminal block · TB DIODE Component terminal block · TB COMP Multilevel terminal block · TB LEVEL Multi-conductor terminal block · TB MULTI Protective-earth terminal block · TB PE Sensor terminal block · TB SENSOR Actuator terminal block · TB ACT Plug-in terminal block · TB PLUG High-current terminal block · TB POWER Terminal jumper bridge · TB BRIDGE Plug and socket connector pair · PLUG SOCKET Connector plug half · PLUG Connector socket half · SOCKET Wire splice · SPLICE Earth connection · EARTH Functional earth · FE Protective equipotential bonding · BOND PE Functional equipotential bonding · BOND FE Surge arrester · SA Gas-discharge protection tube · GDT Spark-gap protective element · SPARK GAP Variable resistor · R VAR Potentiometer · POT Light-dependent resistor · LDR Heating element · HEATER RC network · RC Varistor · VDR Current-measuring shunt · SHUNT Electrolytic capacitor · C ELEC Feedthrough capacitor · C FEED Adjustable capacitor · C ADJ Three-phase power-factor capacitor · CAP 3PH Reactor · L Iron-core reactor · L IRON Gapped-core inductor · L GAP Adjustable-core inductor · L ADJ Diode · D Photodiode · PD Zener diode · ZD DIAC · DIAC Single-phase bridge rectifier · BR 1PH Three-phase bridge rectifier · BR 3PH Silicon-controlled rectifier · SCR Gate-turn-off thyristor · GTO TRIAC · TRIAC Bidirectional breakdown diode · TVS BI Single-phase AC motor · M 1PH AC Single-phase motor with fan · M 1PH FAN Three-phase AC motor · M 3PH Three-phase motor with fan · M 3PH FAN Wound-rotor induction motor · M WR Three-phase synchronous motor · M 3PH SYNC DC motor · M DC Permanent-magnet DC motor · M DC PM Series-excited DC motor · M DC SERIES Separately excited DC motor · M DC SEP DC generator · G DC Compound-excited DC generator · G DC COMP Three-phase synchronous generator · G 3PH SYNC Permanent-magnet synchronous generator · G 3PH PM AC-to-DC power supply · PSU AC-DC DC-to-DC converter · DC-DC DC-to-AC inverter · INV DC-AC DC uninterruptible power supply · UPS DC AC uninterruptible power supply · UPS AC Capacitor buffer module · BUFFER CAP Redundant power-supply decoupling module · PSU RED Analog current signal isolator · ISO I-I Temperature measuring transducer · TEMP TX Photovoltaic inverter · PV INV Single-phase AC source · AC 1PH Three-phase AC source · AC 3PH Photovoltaic generator · PV GEN Solar generating station · SOLAR STN Wind generating station · WIND STN Substation · SUBSTATION Converter substation · CONV STN Generic electrical load · LOAD Transformer-fed indicator lamp · LAMP TX Push-to-test indicator lamp · LAMP TEST LED indicator lamp · LAMP LED Flashing indicator lamp · LAMP FLASH Flashing beacon · BEACON FLASH Rotating beacon · BEACON ROT PLC digital input · DI PLC relay output · DO RELAY PLC transistor output · DO TRANS PLC analog input · AI PLC analog output · AO PLC temperature input · TI Capacitor voltage transformer · CVT / CCVT ANSI/IEEE circuit breaker symbol · CB ANSI/IEEE thermal circuit breaker symbol · CB TH ANSI/IEEE thermal-magnetic circuit breaker symbol · CB TM ANSI/IEEE current-limiting circuit breaker symbol · CB LIM ANSI/IEEE circuit breaker with undervoltage release symbol · CB UV ANSI/IEEE circuit breaker with electronic trip unit symbol · CB ETU ANSI/IEEE disconnector symbol · Isolator ANSI/IEEE switch-disconnector symbol · SD ANSI/IEEE lockable disconnector symbol · DS LOCK ANSI/IEEE lockable switch-disconnector symbol · SD LOCK ANSI/IEEE fused switch symbol · SW FUSE ANSI/IEEE fuse symbol · FU ANSI/IEEE fuse-switch symbol · FUSE SW ANSI/IEEE current transformer symbol · CT ANSI/IEEE current transformer with two secondaries symbol · CT 2SEC ANSI/IEEE tapped-secondary current transformer symbol · CT TAP ANSI/IEEE voltage transformer symbol · VT / PT ANSI/IEEE power transformer symbol · TX ANSI/IEEE electrostatically screened transformer symbol · TX SCREEN ANSI/IEEE three-winding transformer symbol · TX 3W ANSI/IEEE adjustable-ratio transformer symbol · TX ADJ ANSI/IEEE single-phase autotransformer symbol · AT 1PH ANSI/IEEE reactor symbol · L ANSI/IEEE iron-core reactor symbol · L IRON ANSI/IEEE gapped-core inductor symbol · L GAP ANSI/IEEE adjustable-core inductor symbol · L ADJ ANSI/IEEE normally open contact symbol · NO ANSI/IEEE normally closed contact symbol · NC ANSI/IEEE changeover contact symbol · CO ANSI/IEEE relay coil symbol · Coil ANSI/IEEE mechanically latched relay coil symbol · K LATCH ANSI/IEEE relay reset coil symbol · K RESET ANSI/IEEE polarised relay coil symbol · K POL ANSI/IEEE ac relay coil symbol · K AC ANSI/IEEE relay coil with diode suppression symbol · K DIODE ANSI/IEEE relay coil with rc suppression symbol · K RC ANSI/IEEE on-delay timer relay symbol · TON ANSI/IEEE off-delay timer relay symbol · TOFF ANSI/IEEE maintained normally-open contact symbol · NO HOLD ANSI/IEEE maintained normally-closed contact symbol · NC HOLD ANSI/IEEE early-make normally-open contact symbol · NO EARLY ANSI/IEEE late-make normally-open contact symbol · NO LATE ANSI/IEEE early-break normally-closed contact symbol · NC EARLY ANSI/IEEE late-break normally-closed contact symbol · NC LATE ANSI/IEEE motor overload trip nc contact symbol · OL NC ANSI/IEEE motor overload alarm no contact symbol · OL NO ANSI/IEEE normally open pushbutton symbol · PB NO ANSI/IEEE normally closed pushbutton symbol · PB NC ANSI/IEEE illuminated normally-open pushbutton symbol · PB NO LAMP ANSI/IEEE illuminated normally-closed pushbutton symbol · PB NC LAMP ANSI/IEEE maintained normally-open pushbutton symbol · PB NO HOLD ANSI/IEEE maintained normally-closed pushbutton symbol · PB NC HOLD ANSI/IEEE selector switch symbol · SS ANSI/IEEE three-position maintained selector symbol · SEL 3 HOLD ANSI/IEEE three-position centre-return selector symbol · SEL 3 CRET ANSI/IEEE three-position key selector symbol · KEY SEL 3 ANSI/IEEE four-position maintained selector symbol · SEL 4 HOLD ANSI/IEEE four-position key selector symbol · KEY SEL 4 ANSI/IEEE normally-open limit switch symbol · LS NO ANSI/IEEE normally-closed limit switch symbol · LS NC ANSI/IEEE roller-operated limit switch symbol · LS ROLLER ANSI/IEEE pressure switch no symbol · PS NO ANSI/IEEE pressure switch nc symbol · PS NC ANSI/IEEE temperature switch no symbol · TS NO ANSI/IEEE temperature switch nc symbol · TS NC ANSI/IEEE float level switch no symbol · LS FLOAT NO ANSI/IEEE float level switch nc symbol · LS FLOAT NC ANSI/IEEE liquid flow switch symbol · FS LIQ ANSI/IEEE terminal connection symbol · Terminal ANSI/IEEE numbered terminal symbol · TERM 1 ANSI/IEEE plug and socket connector pair symbol · PLUG SOCKET ANSI/IEEE connector plug half symbol · PLUG ANSI/IEEE connector socket half symbol · SOCKET ANSI/IEEE wire splice symbol · SPLICE ANSI/IEEE protective earth symbol · PE ANSI/IEEE functional earth symbol · FE ANSI/IEEE resistor symbol · R ANSI/IEEE variable resistor symbol · R VAR ANSI/IEEE potentiometer symbol · POT ANSI/IEEE light-dependent resistor symbol · LDR ANSI/IEEE heating element symbol · HEATER ANSI/IEEE varistor symbol · VDR ANSI/IEEE current-measuring shunt symbol · SHUNT ANSI/IEEE capacitor symbol · C ANSI/IEEE electrolytic capacitor symbol · C ELEC ANSI/IEEE feedthrough capacitor symbol · C FEED ANSI/IEEE adjustable capacitor symbol · C ADJ ANSI/IEEE diode symbol · D ANSI/IEEE photodiode symbol · PD ANSI/IEEE zener diode symbol · ZD ANSI/IEEE single-phase bridge rectifier symbol · BR 1PH ANSI/IEEE silicon-controlled rectifier symbol · SCR ANSI/IEEE triac symbol · TRIAC ANSI/IEEE voltmeter symbol · V ANSI/IEEE ammeter symbol · A ANSI/IEEE power-factor meter symbol · PF ANSI/IEEE frequency meter symbol · Hz ANSI/IEEE recording wattmeter symbol · W REC ANSI/IEEE reactive-power meter symbol · var ANSI/IEEE synchronoscope symbol · SYNC SCOPE ANSI/IEEE running-hours meter symbol · HOURS ANSI/IEEE single-phase ac motor symbol · M 1PH AC ANSI/IEEE three-phase ac motor symbol · M 3PH ANSI/IEEE wound-rotor induction motor symbol · M WR ANSI/IEEE dc motor symbol · M DC ANSI/IEEE permanent-magnet dc motor symbol · M DC PM ANSI/IEEE three-phase synchronous generator symbol · G 3PH SYNC ANSI/IEEE dc generator symbol · G DC ANSI/IEEE indicator lamp symbol · Lamp ANSI/IEEE transformer-fed indicator lamp symbol · LAMP TX ANSI/IEEE push-to-test indicator lamp symbol · LAMP TEST ANSI/IEEE led indicator lamp symbol · LAMP LED ANSI/IEEE on-delay normally-open contact symbol · TON NO ANSI/IEEE on-delay normally-closed contact symbol · TON NC ANSI/IEEE off-delay normally-open contact symbol · TOFF NO ANSI/IEEE off-delay normally-closed contact symbol · TOFF NC Positive-operation direction qualifier · Q070109 Manual-operation qualifier · Q021301 Protected-access manual-operation qualifier · Q021302 Pushbutton-operation qualifier · Q021305 Emergency-operation qualifier · Q021308 Rotary-operation qualifier · Q021304 Key-operation qualifier · Q021313 Foot-operation qualifier · Q021310 Lever-operation qualifier · Q021311 Crank-operation qualifier · Q021214 Handwheel-operation qualifier · Q021309 Liquid-level actuation qualifier · Q021401 Event-count actuation qualifier · Q021402 Liquid-flow actuation qualifier · Q021403 Gas-flow actuation qualifier · Q021404 Motor-operation qualifier · Q021326 Timed-operation qualifier · Q021327 Roller-operation qualifier · Q021315 Cam-operation qualifier · Q021316 Cam-profile indication · Q021317 Switch-position function qualifier · Q070106 Isolation-function qualifier · Q070103 Switch-disconnector function qualifier · Q070104 Circuit-breaker function qualifier · Q070102 Power-contactor function qualifier · Q070101 Automatic-trip qualifier · Q070105 Spring-return qualifier · Q070107 Maintained-position qualifier · Q070108 One-way linear-motion qualifier · Q020401R Two-way linear-motion qualifier · Q020402 Transition indication · Q101101 One-way rotary-motion qualifier · Q020403 Two-way rotary-motion qualifier · Q020404 Limited two-way rotary-motion qualifier · Q020405 Unidirectional propagation qualifier · Q020501 Simultaneous bidirectional propagation qualifier · Q020502 Alternating bidirectional propagation qualifier · Q020503 Signal-transmission qualifier · Q020504 Signal-reception qualifier · Q020505 Outbound-energy-flow qualifier · Q020506 Inbound-energy-flow qualifier · Q020507 Bidirectional-energy-flow qualifier · Q020508 Thermal-effect qualifier · Q020801 Magnetic-effect qualifier · Q020802 Magnetostrictive-effect qualifier · Q020803 Magnetic-field-effect qualifier · Q020804 Non-ionising radiation qualifier · Q020901 Ionising-radiation qualifier · Q020903 Presumed-fault-location indication · Q021701 Insulation-failure indication · Q021702 Two-phase winding connection · Q060201 Partial-V winding connection · Q060202 Four-phase winding with accessible connection · Q060203 Three-phase T winding connection · Q060204 Six-phase double-delta winding connection · Q060210 Six-phase polygon winding connection · Q060211 Six-phase star winding connection · Q060212 Six-phase double-zigzag winding connection · Q060213 Direct-current supply qualifier · Q020201 Alternating-current supply qualifier · Q020204 Rectified-current with AC component qualifier · Q020212 Automatic mechanical-return indication · Q021207 Mechanical stop-latch indication · Q021208 Mechanical stop latch in neutral state · Q021209 Mechanical stop latch in engaged state · Q021210 Mechanical interlock between devices · Q021211 Two-way latching device · Q1020603 Manually released latching device · Q1020604 Key-controlled two-way latching device · Q1029603 Mechanical clutch connection · Q021216 Disconnected mechanical coupling · Q021217 Engaged mechanical coupling · Q021218 Mechanical gear connection · Q021223 Thermocouple with terminal board · HTC1LTB Pyrometer indication · HIN1P25 Clock indication · HIN1P29 Minute-pulse clock contact · HIN1P33 Pressure-to-current converter · HIN1B10 Single-phase AC-to-DC current converter · HIN1G1 Tachometric dynamo · HIN1B11 Impulse tachometric transducer · HIN1B12 Optical tachometric transducer · HIN1B13 Audible bell · HAN1B Audible buzzer · HAN1Z Audible siren · HAN1S Loudspeaker annunciation · HAN1B7 Combined loudspeaker and microphone · HAN1B8 Microphone input · HAN1B9 Solenoid valve actuator · HSV1 Solenoid closing function for an open valve · HSV1Y1 Electromagnetic brake actuator · HSV1Y4 Solenoid-valve NO auxiliary contact · HSV21 Solenoid-valve NC auxiliary contact · HSV22 Ultrasonic proximity switch · HPX1U Ultrasonic NO switching output · HPX11U Ultrasonic NC switching output · HPX12U Three-wire ultrasonic sensor · HPX11U3 Touch-sensitive switch · HPX1TS Touch-switch NO output · HPX11TS Touch-switch NC output · HPX12TS Three-wire touch-sensitive switch · HPX11TS3 Phase-to-phase voltmeter selector · HSW1S90 Phase-to-neutral voltmeter selector · HSW1S91 Combined line and phase voltmeter selector · HSW1S92 Two-network voltage measurement selector · HSW1S93 Three-point current measurement selector · HSW1S94 Four-point current measurement selector · HSW1S95 Latched pull-cord switch · HPC11L Latched foot-operated switch · HFT11L Latched lever-operated switch · HPB11LSL Three-phase motor with four connections · HMO14 Three-phase induction motor with series excitation · HMO1M3 Star-stator wound-rotor motor with rotor starter · HMO1M5 Six-pole asynchronous motor · HMO1M11 Single-phase series-connected AC motor · HMO1M10 Single-phase synchronous motor · HMO1M16 Permanent-magnet linear DC motor · HMO1M14 Permanent-magnet stepping motor · HMO1M15 Shunt-excited DC motor · HMO1M8 Resistor with disconnecting slider · HVR1R5 Carbon-disc variable resistor · HVR1R8 Magnetoresistive element · HVR1S00689 Differential capacitor · HCA1_S00573 Preset-adjustable capacitor · HCA1_S00575 Split adjustable capacitor · HCA1_S00579 Cable identification marker · HW01 Additional cable-core marker · HW02 Twisted-pair indication · HT0_TW Single power receptacle · HCN1RSGL Duplex power receptacle · HCN1RDUP Generic device boundary · HDV1T6 Standalone source cross-reference · HA2S1_REF Standalone destination cross-reference · HA2D1_REF Reference-only wire arrow · HA1X1 One-line connector representation · HC01PJ_1- One-line terminal representation · HT0001_1- One-line cable identification · HW01_1- One-line bus tap · HDV1_BT_1- One-line power receptacle · HC01WR_1- Connector retaining wire identity · HC01PJ Connector changing wire identity · HCN1PJ Terminal carrying wire identification · HT0W02 Terminal with wire-number transition · HT1002 Conductor connection junction · JUNCTION Unconnected conductor crossing · CROSSING Three-phase conductor group · 3~ Dy5 transformer connection reference · Dy5 Dd6 transformer connection reference · Dd6 Yd5 transformer connection reference · Yd5 Yy6 transformer connection reference · Yy6 Yd11 transformer connection reference · Yd11 Dy11 transformer connection reference · Dy11 Dz0 transformer connection reference · Dz0 Yz5 transformer connection reference · Yz5 Dz6 transformer connection reference · Dz6 Yz11 transformer connection reference · Yz11 Schottky diode · SBD Unidirectional TVS diode · TVS Light-emitting diode · LED Varactor diode · VAR PIN diode · PIN NPN bipolar transistor · NPN PNP bipolar transistor · PNP NPN Darlington transistor · NPN-DAR PNP Darlington transistor · PNP-DAR N-channel JFET · N-JFET P-channel JFET · P-JFET N-channel enhancement MOSFET · N-MOS P-channel enhancement MOSFET · P-MOS N-channel depletion MOSFET · N-DMOS Insulated-gate bipolar transistor · IGBT MOSFET body diode · BODY-D GaN enhancement-mode HEMT · E-HEMT Integrated gate-commutated thyristor · IGCT NPN phototransistor · PHOTO-NPN Phototransistor optocoupler · OPTO-TR Photodiode optocoupler · OPTO-PD Phototriac optocoupler · OPTO-TRIAC Photovoltaic MOSFET driver · PV-DRV Capacitive digital isolator · DIG-ISO Isolated gate driver · ISO-GD Low-side gate driver · LS-GD High-side gate driver · HS-GD Bootstrap gate-drive supply · BOOT Ideal-diode controller · IDEAL-D Hot-swap controller · HOT-SWAP Electronic fuse IC · EFUSE Half-bridge power module · HB-MOD Three-phase sixpack power module · 6-PACK AND gate · AND OR gate · OR NAND gate · NAND NOR gate · NOR Exclusive-OR gate · XOR Exclusive-NOR gate · XNOR Logic inverter · NOT Non-inverting logic buffer · BUF Three-state logic buffer · 3STATE Schmitt-trigger inverter · SCHMITT-NOT Schmitt-trigger buffer · SCHMITT Positive-edge D flip-flop · D-FF Negative-edge JK flip-flop · JK-FF Set-reset latch · SR-LATCH Transparent D latch · D-LATCH Serial-in parallel-out register · SIPO Parallel-in serial-out register · PISO Shift register with output latch · SHIFT-LATCH Ripple binary counter · CTR-RIP Synchronous binary counter · CTR-SYNC Decoded decade counter · DECADE Retriggerable monostable · ONE-SHOT Binary decoder / demultiplexer · DEC Priority encoder · ENC-PRI Digital multiplexer · MUX Digital magnitude comparator · MAG-COMP Binary full adder · ADD Logic bus transceiver · BUS-TR Logic voltage-level translator · LEVEL Open-collector buffer · OC-BUF Parity generator / checker · PARITY Phase-locked loop · PLL Voltage-controlled oscillator · VCO Clock generator · CLK-GEN Watchdog timer · WDT Operational amplifier · OP-AMP Voltage comparator · COMP Instrumentation amplifier · INA Difference amplifier · DIFF-AMP Fully differential amplifier · FDA Current-sense amplifier · CSA Isolation amplifier · ISO-AMP Operational transconductance amplifier · OTA Analogue multiplier · MULT Analogue bilateral switch · A-SW Analogue multiplexer · A-MUX Sample-and-hold amplifier · S/H Analogue-to-digital converter · ADC Digital-to-analogue converter · DAC Series voltage reference · VREF-S Shunt voltage reference · VREF-H Precision rectifier · PREC-RECT RMS-to-DC converter · RMS-DC Voltage / frequency converter · V/F Inverting amplifier circuit · INV-AMP Non-inverting amplifier circuit · NI-AMP Op-amp integrator · INTEGRATOR Op-amp differentiator · DIFFERENTIATOR Active low-pass filter · LPF Active high-pass filter · HPF Active band-pass filter · BPF Active notch filter · NOTCH Transimpedance amplifier · TIA Buck converter topology · BUCK Boost converter topology · BOOST Inverting buck-boost topology · INV-BB Four-switch buck-boost topology · 4SW-BB SEPIC converter topology · SEPIC Cuk converter topology · CUK Zeta converter topology · ZETA Flyback converter topology · FLYBACK Forward converter topology · FORWARD Active-clamp forward topology · ACF Push-pull converter topology · PUSH-PULL Half-bridge DC converter topology · HB-DC Full-bridge DC converter topology · FB-DC Phase-shifted full-bridge topology · PSFB LLC resonant converter topology · LLC Dual-active-bridge topology · DAB Single-phase voltage-source inverter · 1PH-VSI Three-phase voltage-source inverter · 3PH-VSI Neutral-point-clamped inverter · NPC Active front-end rectifier · AFE Synchronism check · 25 Undervoltage · 27 Directional power · 32 Current unbalance / negative sequence · 46 Thermal protection · 49 Instantaneous overcurrent · 50 Time overcurrent · 51 AC circuit breaker · 52 Overvoltage · 59 Directional overcurrent · 67 AC autoreclosing · 79 Frequency protection · 81 Lockout · 86 Differential protection · 87 Line switch · 89 Master element · 1 Time-delay starting or closing relay · 2 Checking or interlocking relay · 3 Master contactor · 4 Stopping device · 5 Starting circuit breaker · 6 Rate-of-change relay · 7 Control power disconnecting device · 8 Reversing device · 9 Unit sequence switch · 10 Multifunction device · 11 Overspeed device · 12 Synchronous-speed device · 13 Underspeed device · 14 Speed or frequency matching device · 15 Data communications device · 16 Shunting or discharge switch · 17 Accelerating or decelerating device · 18 Starting-to-running transition contactor · 19 Electrically operated valve · 20 Distance protection · 21 Equalizer circuit breaker · 22 Temperature control device · 23 Overexcitation protection · 24 Apparatus thermal device · 26 Flame detector · 28 Isolating contactor · 29 Annunciator relay · 30 Separate excitation device · 31 Position switch · 33 Master sequence device · 34 Brush-operating or slip-ring short-circuiting device · 35 Polarity device · 36 Undercurrent or underpower protection · 37 Bearing protective device · 38 Mechanical condition monitor · 39 Field or loss-of-excitation protection · 40 Field circuit breaker · 41 Running circuit breaker · 42 Manual transfer or selector device · 43 Unit sequence starting relay · 44 Atmospheric condition monitor · 45 Phase-sequence or voltage-balance protection · 47 Incomplete-sequence relay · 48 Exciter or DC generator relay · 53 Turning-gear engaging device · 54 Power factor protection · 55 Field application relay · 56 Short-circuiting or grounding device · 57 Rectification failure relay · 58 Voltage or current balance relay · 60 Density switch or sensor · 61 Time-delay stopping or opening relay · 62 Pressure switch or relay · 63 Ground detector protection · 64 Governor · 65 Notching or jogging device · 66 Blocking or out-of-step supervision · 68 Permissive control device · 69 Rheostat · 70 Level switch or relay · 71 DC circuit breaker · 72 Load-resistor contactor · 73 Alarm relay · 74 Position-changing mechanism · 75 DC overcurrent relay · 76 Telemetering device · 77 Phase-angle or out-of-step protection · 78 Flow switch or relay · 80 DC load-measuring reclosing relay · 82 Automatic selective control or transfer relay · 83 Operating mechanism · 84 Pilot or carrier receiver relay · 85 Auxiliary motor or motor-generator · 88 Regulating device · 90 Voltage directional relay · 91 Voltage and power directional relay · 92 Field-changing contactor · 93 Tripping or trip-free relay · 94 Phase distance protection · 21P Ground distance protection · 21G Admittance-based earth-fault protection · 21YN Auxiliary-input undervoltage protection · 27A Main-input undervoltage protection · 27M Reactive-power undervoltage protection · 27Q Low-voltage ride-through supervision · 27T Wattmetric earth-fault protection · 32N Directional reactive-power protection · 32V Reverse-power protection · 32R Underpower protection · 32U Generator current-unbalance protection · 46G Phase-discontinuity protection · 46PD RTD-based thermal protection · 49R Motor thermal-model protection · 49M Instantaneous phase overcurrent · 50P Instantaneous neutral overcurrent · 50N Instantaneous ground overcurrent · 50G Instantaneous negative-sequence overcurrent · 50Q Calculated residual instantaneous overcurrent · 50R Measured ground instantaneous overcurrent · 50X Circuit-breaker failure protection · 50BF Motor jam or stall protection · 50J Time phase-overcurrent protection · 51P Time neutral-overcurrent protection · 51N Time ground-overcurrent protection · 51G Time negative-sequence overcurrent · 51Q Calculated residual time-overcurrent · 51R Measured ground time-overcurrent · 51X Voltage-dependent overcurrent · 51V Apparent power-factor supervision · 55A Displacement power-factor supervision · 55D Residual or neutral overvoltage · 59N Negative-sequence overvoltage · 59Q Auxiliary-input overvoltage · 59A Main-input overvoltage · 59M Field ground-fault protection · 64F Stator ground-fault protection · 64G Directional phase-overcurrent · 67P Directional neutral-overcurrent · 67N Directional ground-overcurrent · 67G Directional negative-sequence overcurrent · 67Q Calculated residual directional overcurrent · 67R Measured ground directional overcurrent · 67X Multifrequency admittance earth-fault protection · 67YN Transient or intermittent earth-fault protection · 67NIEF Trip-coil monitoring · 74TCM Voltage vector-shift protection · 78VS Underfrequency protection · 81U Overfrequency protection · 81O Rate-of-change-of-frequency protection · 81R Transformer differential protection · 87T Busbar differential protection · 87B Generator differential protection · 87G Motor differential protection · 87M Line current differential protection · 87L Neutral differential protection · 87N Negative-sequence differential protection · 87Q Restrained current differential protection · 87R Unrestrained high-set differential protection · 87H Restricted ground differential protection · 87GD Switchgear panel · Panel Switchboard · Board Ring main unit · RMU Transformer envelope · Transformer GA Battery storage cabinet · BESS cabinet Power conversion cabinet · PCS cabinet Generator package · Genset GA Transfer-switch assembly · ATS Control / marshalling cabinet · Control GA Cable ladder / tray · Cable support Busbar trunking · Busway Mounting plate · Plate Terminal strip assembly · Terminal strip Air circuit breaker · ACB Moulded-case circuit breaker · MCCB Miniature circuit breaker · MCB Residual-current circuit breaker · RCCB Residual-current breaker with overcurrent protection · RCBO DC circuit breaker · GA Motor-protection circuit breaker · MPCB Switch disconnector · GA Fuse-switch disconnector · GA Fuse holder · GA Power contactor · GA Reversing contactor assembly · GA Star-delta starter assembly · GA Thermal overload relay · GA Electronic motor overload relay · GA Soft starter · GA Variable-frequency drive · VFD Drive braking resistor · GA AC line reactor · GA Control transformer · GA Dry-type transformer enclosure · GA Oil-filled transformer installation · GA Neutral earthing resistor cabinet · NER Power-factor-correction capacitor bank · GA Active harmonic filter cabinet · GA Surge protective device assembly · SPD DIN-rail AC/DC power supply · GA DIN-rail DC/DC converter · DC DC redundancy module · GA DC buffer module · GA DC UPS module · GA Battery charger · DC AC UPS cabinet · GA UPS maintenance bypass panel · GA Station DC battery rack · GA PLC CPU module · GA PLC power module · GA Digital input module · GA Digital output module · GA Analogue input module · GA Analogue output module · GA Remote I/O station · GA HMI touchscreen · GA Industrial panel PC · GA Industrial Ethernet switch · GA Industrial VPN router · GA Fibre-optic patch panel · GA Communication gateway · GA Interface relay module · GA Relay socket · GA Timer relay · GA Safety relay module · GA Signal conditioner · GA Terminal marshalling interface · GA Feed-through terminal block · GA Protective-earth terminal block · GA Multi-level terminal block · GA Fuse terminal block · GA Disconnect terminal block · GA CT shorting test terminal · GA Distribution terminal block · GA Pluggable terminal connector · GA Terminal end stop · GA Terminal marker strip · GA DIN mounting rail · GA Slotted wiring duct · GA Cable gland · GA Cable-entry frame · GA Bulkhead connector · GA Cable cleat · GA Perforated cable tray · GA Wire-mesh cable basket · GA Cable-tray horizontal bend · GA Cable-tray vertical riser · GA Cable support bracket · GA Cable trench · GA Cable pit · GA Cable duct bank · GA Earth bar · GA Neutral bar · GA Flexible busbar connection · GA Rigid busbar assembly · GA Busbar support insulator · GA Busway tap-off unit · GA LV incomer compartment · GA LV feeder compartment · GA Bus-coupler compartment · GA Cable termination compartment · GA Busbar compartment · GA Metering compartment · GA Motor control centre lineup · GA Withdrawable motor feeder unit · GA MV vacuum circuit-breaker truck · GA Switchgear arc exhaust plenum · GA Protection relay panel · GA Panel power meter · GA Energy submeter · GA Window current transformer · GA Split-core current transformer · GA Voltage transformer assembly · VT Wall-mounted junction enclosure · GA Floor-standing enclosure · GA Enclosure plinth · GA Enclosure gland plate · GA Enclosure door swing envelope · GA Equipment maintenance envelope · GA Equipment removal route · GA Switchroom egress path · GA Enclosure anti-condensation heater · GA Enclosure thermostat · GA Enclosure hygrostat · GA Enclosure filter fan · GA Enclosure air conditioner · GA Enclosure air-to-air heat exchanger · GA Switchroom supply fan · GA Switchroom exhaust fan · GA Ventilation intake louver · GA Motorised ventilation damper · GA Backdraft damper · GA Fire damper · GA Smoke-control damper · GA Generator day tank · GA Generator bulk fuel tank · GA Generator fuel transfer pump · GA Generator fuel bund · GA Generator exhaust silencer · GA Generator exhaust flexible connection · GA Generator exhaust stack · GA Generator radiator discharge duct · GA Generator remote radiator · GA Generator vibration isolator · GA Generator acoustic canopy · GA Generator coolant heater · GA Generator starting battery · GA Generator paralleling controller · GA PV string combiner box · GA PV inverter cabinet · GA PV DC isolator enclosure · GA MPPT solar charge controller · GA Battery inverter-charger · GA Battery management system module · BMS Battery DC disconnect assembly · GA Battery precharge assembly · DC Battery DC bus distribution module · DC Battery current shunt · DC Energy-management controller · EMS Outdoor energy-storage container · GA Battery cooling unit · GA Battery fire-system interface panel · GA Smoke detector installation point · GA Fire alarm control panel location · GA Emergency stop station · GA Pilot-light station · GA Selector-switch station · GA Trapped-key interlock assembly · GA Door-mounted pushbutton enclosure · GA Panel service outlet · GA Panel inspection lighting · GA AutomationDirect BRX Series PLC · BRX Series PLC AutomationDirect CLICK PLCs · CLICK PLCs AutomationDirect Productivity1000 PAC · Productivity1000 PAC AutomationDirect Productivity2000 PAC · Productivity2000 PAC AutomationDirect Productivity3000 PAC · Productivity3000 PAC AutomationDirect Terminator Field I/O · Terminator Field I/O AutomationDirect Protos X Field I/O · Protos X Field I/O AutomationDirect ZIPLinks · ZIPLinks AutomationDirect DINnectors · DINnectors AutomationDirect Konnect-It DIN-rail terminals · Konnect-It DIN-rail terminals AutomationDirect C-more Panels · C-more Panels AutomationDirect C-more Micro Graphic Panels · C-more Micro Graphic Panels AutomationDirect GS and DURApulse AC drives · GS and DURApulse AC drives AutomationDirect LR Series line reactors · LR Series line reactors AutomationDirect Bimed cable glands · Bimed cable glands AutomationDirect ZIPport Multi-Wire Connectors · ZIPport Multi-Wire Connectors AutomationDirect ZIPport Panel Interface Connectors · ZIPport Panel Interface Connectors AutomationDirect Gladiator CFS disconnects · Gladiator CFS disconnects AutomationDirect WMZT miniature circuit breakers · WMZT miniature circuit breakers AutomationDirect Edison Class T fuses · Edison Class T fuses AutomationDirect Edison Power Distribution Blocks · Edison Power Distribution Blocks AutomationDirect Stride VPN · Stride VPN AutomationDirect AcuAmp · AcuAmp Fuji Electric BM3 manual motor starters · BM3 manual motor starters Fuji Electric SC contactors and thermal overload relays · GA Fuji Electric SC-NEXT contactors · SC-NEXT contactors Fuji Electric Orange Line / Odyssey contactors · Orange Line / Odyssey contactors Fuji Electric Combination starters · Combination starters Fuji Electric G-Twin Lambda circuit breakers · G-Twin Lambda circuit breakers Fuji Electric G-Twin circuit breakers · G-Twin circuit breakers Fuji Electric EA-UL / SA-UL circuit breakers · EA-UL / SA-UL circuit breakers Fuji Electric EG-UL / SG-UL circuit breakers · EG-UL / SG-UL circuit breakers Fuji Electric SK contactors and relays · SK contactors and relays TDK-Lambda D1SE120-xx-A3 · D1SE120-xx-A3 TDK-Lambda D1SE240-xx-A3 · D1SE240-xx-A3 TDK-Lambda D1SE480-xx-A3 · D1SE480-xx-A3 TDK-Lambda DBM20 · DBM20 TDK-Lambda DRB15 · DRB15 TDK-Lambda DRB30 · DRB30 TDK-Lambda DRB480 · DRB480 TDK-Lambda DRF960 · DRF960 TDK-Lambda DRM40 · DRM40 TDK-Lambda DUSH960-1248-1M · DUSH960-1248-1M PULS QS20.241 · QS20.241 Terasaki TemPower AT air circuit breakers · TemPower AT air circuit breakers Terasaki / NHP TemBreak 1 legacy MCCBs · TemBreak 1 legacy MCCBs Schneider Electric MiCOM protection relays · MiCOM protection relays Invertek Drives Optidrive Eco · Optidrive Eco Schneider Electric MasterPact MTZ · MasterPact MTZ Schneider Electric MasterPacT MTZ Active · MasterPacT MTZ Active Schneider Electric ComPacT NSX, new generation · ComPacT NSX, new generation Schneider Electric ComPacT NSXm, new generation · ComPacT NSXm, new generation Schneider Electric ComPacT for DC networks, new generation · ComPacT for DC networks, new generation Schneider Electric Compact INS/INV · Compact INS/INV Schneider Electric Acti9 iC60 · Acti9 iC60 Schneider Electric Acti9 iC60 RCBO · Acti9 iC60 RCBO Schneider Electric PrismaSeT 6300 · PrismaSeT 6300 Schneider Electric PrismaSeT G · PrismaSeT G Schneider Electric TeSys K contactors · TeSys K contactors Schneider Electric TeSys Giga contactors · TeSys Giga contactors Schneider Electric TeSys Deca overload relays · TeSys Deca overload relays Schneider Electric TeSys GV2, LC · TeSys GV2, LC Schneider Electric PowerLogic PM5000 · PowerLogic PM5000 Schneider Electric PowerLogic PM8000 · PowerLogic PM8000 Schneider Electric PowerLogic P5 protection relays · PowerLogic P5 protection relays Schneider Electric PowerLogic PFC Capacitor Banks · PowerLogic PFC Capacitor Banks Schneider Electric PowerLogic T500 Substation Controller · PowerLogic T500 Substation Controller Schneider Electric TransferPacT · TransferPacT ABB MNS switchgear · MNS switchgear ABB ReliaGear SG switchgear · ReliaGear SG switchgear ABB UniGear switchgear · UniGear switchgear Protection relay IED · GA Medium-voltage switchgear lineup · GA Low-voltage switchgear lineup · GA Source-transfer switch assembly · GA Substation RTU · GA Industrial ventilation fan · GA Lithium battery module · GA DIN-rail adapter accessory · GA Combined fire-smoke damper · GA Victron Energy MultiPlus-II · MultiPlus-II Victron Energy Quattro · Quattro Victron Energy SmartSolar MPPT RS · SmartSolar MPPT RS Victron Energy Cerbo GX · Cerbo GX Victron Energy Lynx Distributor · Lynx Distributor Victron Energy Lynx Smart BMS NG · Lynx Smart BMS NG Victron Energy Lithium NG Batteries · Lithium NG Batteries Victron Energy SmartShunt · SmartShunt Victron Energy Skylla-IP65 · Skylla-IP65 Victron Energy Multi RS Solar · Multi RS Solar Victron Energy MultiPlus-II 2x 120V · MultiPlus-II 2x 120V Victron Energy DIN35 adapter · DIN35 adapter DEIF iE 250 controllers · iE 250 controllers Westermo PS2-60 · PS2-60 Westermo Lynx 5612-E-F4G-T8G-LV · Lynx 5612-E-F4G-T8G-LV Dagartech BGPSW 15 ST · BGPSW 15 ST Dagartech DGB 415 ST · DGB 415 ST Greenheck QEI inline fan · QEI inline fan Greenheck QEID inline fan · QEID inline fan Greenheck TBI-FS inline fan · TBI-FS inline fan Greenheck VAB fan · VAB fan Greenheck VAD fan · VAD fan Greenheck USF fan · USF fan Greenheck APH plenum fan · APH plenum fan Greenheck SBE wall fan · SBE wall fan Greenheck SBS wall fan · SBS wall fan Greenheck SE wall fan · SE wall fan Greenheck ESD-435 louver · ESD-435 louver Greenheck ESD-635 louver · ESD-635 louver Greenheck AFL-501 louver · AFL-501 louver Greenheck FSD-311 damper · FSD-311 damper Greenheck FSD-211 damper · FSD-211 damper Greenheck FD-150 damper · FD-150 damper Power cable joint · CABLE JOINT Power quality meter · PQM
81O Protection functions Overfrequency protection Supervises frequency above the defined operating criterion.
Drawing use SLD / Schematic
Application Metering & protection
Reference family IEEE / ANSI / Manufacturer A distinction that matters The suffix O is the letter O for overfrequency; use the complete label to avoid confusion with a zero in search or drawing text.
81 Protection functions Frequency protection Frequency protection responds to frequency conditions according to the selected implementation. Underfrequency, overfrequency and rate-of-change functions can be distinguished by additional suffixes and device documentation. A generic 81 reference does not determine which variant is applied.
Drawing use SLD / Schematic
Application Metering & protection
Reference family IEEE / ANSI A distinction that matters Underfrequency, overfrequency and rate-of-change are different functions even when their designations share the number 81.
Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.
