Circuit breakers

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circuit breaker is electrical device to carry load and to isolate in case of fault.

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Circuit breakers

  1. 1. CIRCUIT BREAKER -B. Prasad Chartered Engineer amieclub@gmail.com
  2. 2. TECHNICAL ASPECT  RATED VOLTAGE NORMAL CURRENT RATING SHORT CIRCUIT CURRENT RATING INDOOR/OUTDOOR TYPE MOTORISED/NON- MOTORISED REMOTE/LOCAL OPERATION
  3. 3. Circuit breaker types  Air magnetic  • Oil  • Air blast  • Vacuum  • SF6 gas
  4. 4. Fundamental characteristics of a circuit breaker  Its rated voltage Ue  Its rated current In  Its tripping current level adjustment ranges for overload protection (Iror Irth)   short circuit protection (Im)
  5. 5. Selection of Switching Devices LOW VOLTAGE  Fuse  MCB  ELCB  MCB  MCCB  SFU  ISOLATOR  CHANGE OVER  CNTACTOR MEDIUMHIGH VOLTAGE  ACB  OLCB  VCB  SFC BREAKER  HT FUSE
  6. 6. Breaker parts
  7. 7. VACUUM INTERRUPTER
  8. 8. Vacuum interrupter side view
  9. 9. Interlocks  Breaker may not be taken out unless it is off.  Closed breaker may not go in service position.  Closed breaker will trip when taking outside.  Test position limit switch.  Service position limit switch.  VCB in service and locked.  Service position key.
  10. 10. Rating, selection of breakers  Rated voltage:12 KV to 765KV  Rated current: 200,400,630,800,1000,1250,1600,2000, 2500,3150,4000A  Rated frequency: 50 or 60Hz  Short circuit breaking current:12.5,16,20,25,31.5,40,50,63,80 KA  Rated short time withstand current: 1s
  11. 11. Breaker control circuit
  12. 12. ACB MOUNTED ON CRADLE
  13. 13. ACB CRADLE
  14. 14. SF6 breaker  Known as Sulphur hexafluoride  Suitable for 66 KV to 800KV  Generates greenhouse gas, safety issue
  15. 15. Breaker comparison Functions performed Protections Isolation Control Switchgear Overloads Short-circuit Fuse Yes Yes No No Disconnector No No Yes No Switch No No Yes? Yes Disconnector – fuse Yes Yes Yes No Switch – fuse Yes Yes Yes? Yes Contactor No No  No Yes Circuit- breaker Yes Yes Yes? Yes
  16. 16. ACT FAST AND INITIATE FIRST  बड़ा    सोचो         तेजी से सोचो व     सबसे पहले सोचो  िवचारो     पर िकसी का       एकािधकार नही होता.   ----  धीरभाई अमबानी
  17. 17. Thank you 

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