BSC
Breaker shunt-trip coil
Uses an externally supplied electrical pulse to release the breaker opening mechanism.
Functional block
Electrical symbols.
Explore electrical symbols, functional blocks and circuit arrangements for switchgear, switchrooms, substations, switchyards and microgrids. Detailed explanations, drawing notes, public sources and original SVG/DXF illustrations.
Switchgear
BTCOI
Breaker trip coil one interface
Identifies the first opening coil in a breaker with separately wired trip paths.
Functional block
BTCTI
Breaker trip coil two interface
Identifies the second opening coil and its separately documented protection channel.
Functional block
ITC
Independent trip-supply changeover
Selects an available supply for a documented trip circuit without merging the two source circuits.
Functional block
TPE
Trip-coil pulse extension
Maintains an opening command for the duration required by the selected operating mechanism.
Functional block
TIR
Trip-output interposing relay
Transfers a protective-relay output to an opening circuit with a different electrical duty.
Functional block
TITL
Trip-coil isolation test link
Provides a documented disconnect point between a trip output and its operating coil.
Functional block
PTDM
Protection trip distribution matrix
Routes each protection initiation to the breakers assigned to the affected protection zone.
Functional block
MEP
Manual emergency-trip path
Shows the hardwired opening request issued by the designated emergency control station.
Functional block
LBT
Lockout-mediated breaker trip
Passes a protection initiation through a latched lockout function before the assigned breaker trips.
Functional block
DPT
Direct protection-to-coil trip
Shows an opening output connected to the breaker trip circuit without an intervening lockout function.
Functional block
DTS
Dual-channel trip segregation
Keeps the two documented opening-command channels electrically identifiable through the terminal strip.
Functional block
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Read the drawing, not just the mark
Small details. Different meanings.
Understand symbols, equipment tags and function numbers—and know when a generic object needs a manufacturer drawing.
In plain English
What do electrical symbols tell you?
Electrical symbols are shorthand for equipment, functions and connections. They let you follow how a circuit works without drawing every physical detail.
A simple example
On a microgrid single-line diagram, a current-transformer symbol marks a measurement point and a breaker symbol marks where a circuit can be disconnected. Their labels identify the actual equipment.
What the drawings help you do
Follow the connected lines to trace power or control signals. Use the project legend to interpret symbols and the selected manufacturer's drawings for dimensions and terminal connections.
- Single-line diagram
- A simplified power-system drawing that often uses one line to represent a three-phase circuit.
- Legend
- The key explaining a drawing's symbols and labels.