Switchgear & Protection | Distinguish between circuit breaker and isolator.

Circuit breaker 

1. 

2. Operated ON load /on occurrence of fault. 

3. Heavy current is interrupted, arc is produced hence arc quenching facility is provided.

4. Operation is in oil or gas chamber (not visible). 

5. Big sound on operation. 

6. Costly / Expensive. 

7. Periodic maintenance is very much required.

8. Occupy more space.

9. Requires tripping circuit for operation.

10. Manually operated in normal condition & automatically operated in fault condition. 

11. Types are as follows:

    (a) Air break C. B.

    (b) Oil C.B.

    (c) Air blast C.B.

    (d) Vacuum C.B.

    (e) SF6 C.B.

    (f) MCCB etc. 

12. Complicated in construction. 

Isolator

1. 

2. Operated on NO load.

3. No arcing during ON/OFF, so no arc quenching facility provision. 

4. Visible operation in open air (opening & closing of contacts). 

5. Noise-less operation.

6. Economical 

7. No periodic maintenance required (only contact cleaning). 

8. Occupy less space.

9. No tripping circuit.

10. Operation may be manual/mechanical/pneumatic. 

11. Types are as follows:

        (a) Vertical break type

        (b) Horizontal break type

        (c) Pantograph type etc. 

12. Simple in construction.