IED
Numerical protection relay (IED)
Single relay block on an SLD that lists the protection functions it provides, with CT, VT and trip connections.
SLD / Schematic
Symbols · TCS
Trip-circuit supervision relay
Relay that passes a small current through the trip circuit to check continuity and alarms if the circuit is broken.
In plain English
What does Trip-circuit supervision relay mean?
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.
A simple example
Schemes differ in whether they supervise the circuit with the breaker open and closed, which needs resistors or connections across the breaker auxiliary contacts. The symbol shows the relay but the reader must check which states are actually covered.
What the drawings help you do
Check supervision covers both breaker positions. Verify the supervision current cannot operate the trip coil. Trip-circuit supervision monitors trip path continuity; a lockout relay latches after a trip.
This particular reference
Relay that passes a small current through the trip circuit to check continuity and alarms if the circuit is broken. Trip-circuit supervision monitors trip path continuity; a lockout relay latches after a trip.
- Normally open / normally closed
- The contact state in the normal condition defined for the drawing.
- Coil
- A wound conductor that can produce a magnetic field when energised.
- Terminal
- An identified point where a conductor connects.
Read the source: Relion 620: functions, codes and symbols · IEC graphical symbols for diagrams
Schematic · TCS
What it represents
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.
Schemes differ in whether they supervise the circuit with the breaker open and closed, which needs resistors or connections across the breaker auxiliary contacts. The symbol shows the relay but the reader must check which states are actually covered.
How to read it
- Check supervision covers both breaker positions.
- Verify the supervision current cannot operate the trip coil.
Information to show or reference
- Show connections across trip contacts
- State supervised breaker states
- Reference alarm output
A distinction that matters
Trip-circuit supervision monitors trip path continuity; a lockout relay latches after a trip.
Sources you can follow
These public references support the explanation and provide further detail. Their graphics and downloadable files remain with their publishers.
Relion 620: functions, codes and symbols
Public relay function list including trip-circuit supervision.
IEC graphical symbols for diagrams
IEC context for graphical symbols used in diagrams; no IEC graphic is reproduced.
About this graphic
This illustration was authored independently by Elora Grid to explain the concept. It is not reproduced from a customer drawing, an official standard graphic or a manufacturer CAD file. Its correspondence to an exact IEC or IEEE symbol identifier has not been certified.
SVG and DXF downloads contain this original artwork. DXF uses unscaled drawing units; a GA envelope supplies no product dimensions, clearances or fabrication information. Original artwork is available under CC BY 4.0. Third-party references retain their own terms.
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