Circuit Breaker Tripping Schemes

What is circuit breaker:

Generally we all are know circuit breakers are used to protect the equipment from abnormal or faulty conditions. and also circuit breaker also used for control the equipment ON/OFF. there are different types of circuit breaker used in electrical field and depend on voltage and current rating its classified into different types. the some of the circuit breakers you can see below,

  1. MCB- up to 63A, 240V
  2. MCCB up to 1000A, 415V
  3. ACB    up to 10000A,415V
  4. VCB up to  1000A, 1000V – 11000V
  5. OCB up to 1200A , 1KV- 33KV
  6. SF6 above 33KV

Circuit Breaker Tripping Schemes

There are two types of tripping systems is there. these are given below,

  1. Relay with make type contact.
  2. Relay with break type contact.


Relay with make type contact:

This type of tripping mechanism the relays are connected with star connection to circuit breaker. the auxiliary contacts of the relay all are connected in parallel and its further connected series with breaker tripping coil and finally its connected to battery supply.
now we can see the working of relay with make type contact mechanism. when ever the fault occur in any one of the phase then the relay has to activate and close its auxiliary contacts. then battery supply will comes to breaker tripping coil and breaker is tripped. so the connected equipment will be safe. when ever the fault will be reset or stop then relay give the commend to reset that auxiliary contacts to normal. the below diagram will show you working operation of relay with make type contact.


Relay with break type contact:

in this type of tripping mechanism the relays are connected in series connection. the auxiliary contacts of relay are connected in series with tripping coil of circuit breaker. each phase of circuit breaker tripping coil also connected in star and its series connected with CT secondary terminal in main supply. in this type of tripping mechanism getting power from main supply only.

the working of this tripping mechanism at normal condition the relay contacts are closed position. when ever the fault occur in the line the relay contacts are opened and the circuit breaker tripping coils are activated and the breaker is opened. the below diagram will show the operation relay with break type contact tripping mechanism.

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