CT
Current transformer
A current-measurement transformer used with metering and protection equipment.
SLD / Schematic
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.
Metering & protection
VT / PT
Voltage transformer
A transformer providing a voltage signal for metering or protection.
SLD / Schematic
CT 2SEC
Current transformer with two secondaries
A CT with two secondary windings supplies two documented secondary circuits.
SLD / Schematic
CT TAP
Tapped-secondary current transformer
A tapped CT secondary provides alternative documented transformation ratios through different terminal combinations.
SLD / Schematic
CT PRI
Current transformer with primary conductor indication
This CT representation explicitly identifies the primary conductor passing through the measurement location.
SLD / Schematic
CBCT
Core-balance current transformer
A core-balance CT measures residual current from the net magnetic effect of conductors passing through its window.
SLD / Schematic
CT RES
Residual connection of phase CTs
A residual CT connection combines secondary currents from phase CTs to obtain a residual-current input.
SLD / Schematic
TC
Thermocouple
A thermocouple produces a temperature-dependent voltage associated with its dissimilar-metal junction system.
Schematic
RTD
Resistance temperature detector
An RTD is a temperature sensor whose resistance changes with temperature.
Schematic
V
Voltmeter
A voltmeter indicates electrical potential difference between its measurement inputs.
SLD / Schematic
A
Ammeter
An ammeter indicates current from a direct or instrument-transformed measurement circuit.
SLD / Schematic
PF
Power-factor meter
A power-factor meter indicates the relationship between real and apparent power according to the instrument's measurement method.
SLD / Schematic
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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.