Side-by-side reference

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 referenceCompare with

TCS

Symbols

Trip-circuit supervision relay

A trip-circuit supervision relay monitors the wiring, auxiliary contacts and trip coil of a circuit breaker by passing a current too small to trip it. If the trip circuit is broken or its supply fails, the relay drops out and raises an alarm, so a failed trip path is found before a fault needs it.

Drawing use: Schematic
Application: Metering & protection
Reference family: IEC / Manufacturer

A distinction that matters

Trip-circuit supervision monitors trip path continuity; a lockout relay latches after a trip.

Full reference

IED

Symbols

Numerical protection relay (IED)

A numerical protection relay, or IED, combines many protection, control and measuring functions in one device. Single-line diagrams draw it as a block connected to its CTs, VTs and breaker trip coil, with the enabled functions listed inside or beside it using IEC function symbols or ANSI device numbers.

Drawing use: SLD / Schematic
Application: Metering & protection
Reference family: IEC / Manufacturer

A distinction that matters

An IED block represents a multifunction device; a single measuring relay symbol represents one function.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.