Main circuit breaker.pptx

explanation on main circuit braker

1. Main Circuit breaker Name ： chen yanping E-mail ： [email protected]

2. 1. Function 2. Main parameters Main circuit breaker 3. Structure 4. Operation 5. Maintenance 6. Troubleshooting Content

3. Main circuit breaker is connected in series in main loop to switch on or off catenary side circuit and protect catenary side circuit (short circuit, over load grounding, catenary under voltage, etc.) 1.General Main Circuit Breaker type BVAC N99

4. Item Parameter Remark Rated voltage 30 kV Maximum allowable continuous voltage 31.5 kV Frequency 50 Hz Rated thermal current 1000A Rated short-circuit switch-off current 20 kA Rated short-circuit impulse current (peak value) 40 kA Rated short-time current 25 kA 1 s Maximum switch-off time 60 ms 2.Main Electrical parameters

5. 3. Structure (three main parts)

6. the upper part, which is the high voltage circuit.

7. The intermediate part, which ensures isolation from earth. Vertical insulator

8. The lower part with the electro-pneumatic mechanism and the low voltage circuit. Where is the Pressure switch?

9. Main circuit breaker at off state 4.Operation (1) Closing operation Closer conditions???

10. At reset stage(open ) Electro-valve opening Moving the main contact Creating contact pressure Closed Closing sequence

11. 2.Opening operation, BVAC closed Opening the magnetic holding circuit Open （ 2 ） Opening operation Opening sequences

12. (3)Control of operation S keleton diagram of circuit breaker

13. Sequence diagram ON/OFF: Control switch, closing/opening the circuit breaker. Order given by vehicle sequence diagram HV: Main contact of vacuum switch tube; high voltage. EV: Electro-magnet valve Mm: Holding magnet coil. Caux NO: Auxiliary contact NO( normlly open) Caux NC: Auxiliary contact NO( normlly close) ΔtC : closing time between ON/OFF switch closing and main contacts closing. Δto : Open time from holding current is zero ( IMm =0) to the separation of the main contacts. ΔtNext C: Time until the next closing. ΔtEV : Supply EV time.

14. 5.Maintenance (1)appearance  inspection: Carry out a visual inspection of the circuit breaker and, more specifically, of the state of the insulator ceramics (A) (cracks or damage to enamel) and connections (B) of BTE earthing switch. General maintenance Process

15. (2) Checking tightening torque A (High voltage connections): 67 Nm A （高压接头）： 67 Nm B ( Earthing connections): 50 Nm （接地接头）： 50 Nm C (Circuit breaker fixing screws): 67 Nm （断路器固定螺钉）： 67 Nm 5.Maintenance General maintenance Process

16. 5.Maintenance (3)Inspection of pneumatic circuit Draining the pressure regulator Draining BVAC air tank Checking seals General maintenance Process

17. 5.Maintenance Test requirements (1)The minimum and maximum voltages shall relate to the nominal voltage as follow: Minimum voltage: 0.7Uctrl n Maximum voltage: 1.25Uctrl n (2)The permissible pressure varition in vehicle supply pipe es from: 450kPa ～ 1000kPa (3) measure insulation   resistance (4)Switch-off time

18. The BVAC circuit breaker does not close. The BVAC circuit breaker does not remain closed. 6. Troubleshooting electrical part mechanical part pneumatic circuit

19. Page  19 Thank you ！