ABB Trip circuit supervision relay TCS

Continuous supervision of complete trip circuit independent of circuit breaker position

The supervision relay type TCS is intended for a continuous supervision of circuit breaker trip circuit and gives an alarm for loss of auxiliary supply, faults on the trip coil or its wires independent of the breaker position, faults on the breaker auxiliary contacts and faults in the supervision relay. The trip circuit supervision is a crucial requirements as its failure can cause disconnect of possible network fault and eventually have to be cleared by another upstream protection.

In normal condition, the indicator LE D glows green and output relays are in picked-up condition. In the event of a fault, the supervision relay operates (drops-off)after a delay of 0.6 sec and the indicator LED turns red.

TCS relay product range

• Rated voltage: 24V DC, 30V DC, 48V DC, 100-125V AC/DC, 220-250V AC/DC

• Contact configuration: 1NO+1NC+2C/O

Main benefits

• Highly reliable

• Personnel as well as power system safety

• Easy site installation

Main features

• Continuous supervision of trip circuit independent of the circuit breaker position

• Galvanic isolation between auxiliary supply and supervision circuit

• Delayed operation to avoid spurious signals during circuit breaker operation

• Enables use in sensitive or high resistance circuits

• Extremely low burden on auxiliary source

• Complete range of rated voltages either AC/DC

Features

• Continuous supervision of trip circuit independent of the circuit breaker position

• Extremely low burden on auxiliary source

•  Complete range of rated AC / DC voltage

•  Operation indication for trip circuit healthy and unhealthy

•  Low-level measuring current enables application of relay for high burden circuits

•  Delayed operation to avoid spurious signals during circuit breaker operation

•  Galvanic isolation between auxiliary supply and supervision circuit

Applications

In a protection system the tripping of circuit breaker is crucial. Should an interruption occur in a trip circuit a possible network fault would not be disconnected and the fault would have to be cleared by another up-stream protections in the power system. The supervision function is particularly important when there is only one tripping coil. CB tripping is vital, for instance, for generator circuit breakers or other important circuit breaker in distribution networks.

The supervision relay type TCS is intended for a continuous supervision of circuit breaker trip circuit and gives an alarm for loss of auxiliary supply, faults on the trip-coil or its wires independent of the breaker position, faults on the breaker auxiliary contacts and faults in the supervision relay itself.

Design and principle of operation

The supervision relay TCS is designed to be used for the supervision of trip circuits and other important control and monitoring circuits. Block diagram of the relay is shown in Fig. 1. The supervision function is based on low-level (~ 3 mA) current injection principle.

The injected current is sensed by two opto couplers. The supervision function in three

steady states of circuit breaker-trip circuit can be seen from fig.2. 3 and 4. In normal condition the indicator LED glows green and output relays are in picked-up condition.

If in the event of a fault, the measuring current goes below the operating value of the relay  (0.3 - 0.7 mA) or completely stops flowing, the supervision relay operates (drops-off) after a delay of 0.6 sec and the indicator LED turns red.

The supervision relay, for its functioning requires and auxiliary voltage (AC or DC) of rated value to be connected to the terminals "a" and "b". This voltage can be the same as that of the supervised circuit or it could be a separate source with same magnitude (ac or dc). Should a fault occur in the auxiliary voltage supply the LED does not glow and the output relay drops off. Relays with differing rated voltage for supervision circuit and auxiliary supply can be supplied as special execution.