06.Trip Circuit Supervision

Trip Coil

A trip coil is a key part of a circuit breaker that enables automatic disconnection during electrical faults. It must always be in working condition to ensure protection.

Trip Circuit Supervision

Supervision circuits is a simple circuit mechanism which continuously monitor the coil’s health to detect any failure or disconnection. This ensures reliable breaker operation and system safety. Regular supervision is critical to avoid protection failure during faults.

Method 1 ( Lamp with series Resistor).

The simplest way to supervise a trip coil is by using a series resistor and indication lamp or LED connected across the trip coil circuit. The lamp glows under healthy conditions, indicating that the circuit is complete and the coil is ready to operate. You can see that the  lamp lights up immediately when the MCB is powered on. 

Behaviour During Trip:

• When the relay trips, its contact closes, energizing the trip coil.

• This creates a low-resistance path, effectively short-circuiting the lamp-resistor combination.

• As a result, the lamp goes off during the trip operation  which is normal behaviour and not a fault.

The lamp glows again once the trip contact is reset, indicating that the trip circuit is restored and healthy.

Advantages

Simplicity: Easy to design, install, and understand.

Low Cost: Minimal components make it cost-effective.

Quick Visual Indication: Immediate status visible to operators via the lamp.

No Complex Wiring: Requires minimal control wiring and setup.

Limitation:This method can be used in LV  / MV level upto 33kV, depending on the requirement. 

Disadvantages

No Fault Detail: Cannot distinguish between coil burnout, wiring issue, or loss of supply.

Limited Automation: Not suitable for remote or SCADA-based monitoring.

Continuous Power Draw: The resistor-lamp setup consumes a small but continuous amount of power.

Manual Monitoring Required: Depends on someone noticing the lamp status regularly.

Limitation: This method is not reliable for EHV . 

CB Control : Circuit breaker (CB) will be able to close independently, even if the trip coil is faulty

Partially Dynamic : Its very partially dynamic method only during Trip Contact open time. 

• Single Busbar Configuration

• Single Busbar with Bus section Configuration

• Single Busbar with Transfer busbar configuration

• Single Busbar with Bus section + Transfer bus coupler + Section Isolator configuration

• Double Busbar with Bus coupler Configuration

• Double Busbar with Bus coupler + Bypass Isolator Configuration

• Double Busbar with Bus coupler + Transfer Buscoupler configuration

• Mesh Busbar configuration

• One and Half Breaker Busbar Configuration

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Method 2

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