Overhaul procedures for high-voltage main switches

⚠️ High Voltage Hazards: Strict Adherence to Operating Procedures and Interlocking Requirements

I. Ship's high-voltage main switch overhaul operation procedures

(i) Ship's high-voltage main switch maintenance operation procedures

High-voltage switchboards are usually divided into left and right sides, which are placed in different high-voltage distribution rooms, which are equipped with high-voltage insulated floors, and high-voltage switchboards have a very high level of protection, which are used to ensure the safety of operators.

Inspection process:
Place the ship's HV main switch in the disconnected position → disconnect the corresponding disconnecting switch → close the earthing switch → open the switchgear cabinet → repair the HV circuit breaker.

Recovery Process:
Close the switchgear → disconnect the earth switch → close the corresponding disconnecting switch → place the ship's HV main switch in the working position.

* :: Electrical or mechanical interlocks are provided between the main switch, the disconnecting switch and the earthing switch and the cabinet door to prevent misoperation. Operators must follow the process step by step.

(ii) Ship's high-voltage disconnecting switch operating procedures

Disconnect switches with visible break points.No arc extinguishing device, can't open and close the gate with load.. It must work with the circuit breaker: the disconnecting switch can be disconnected only after the circuit breaker has been disconnected; the circuit breaker cannot break the disconnecting switch when it is in the closed position. Conversely, the disconnecting switch must be closed before the circuit breaker is allowed to close.

(iii) High-voltage grounding switch operating procedures

without an arc extinguishing device.Cannot open or close the gate with load. It should be closed when the power is out for maintenance to ensure that the line is reliably grounded and to prevent accumulation of electric charge affecting personnel or causing three short circuits when the circuit breaker is closed accidentally so that the circuit breaker is tripped immediately. After maintenance, the sequence is: open the grounding switch → close the disconnecting switch → close the circuit breaker.

(iv) High-voltage main switch withdrawal and feeding operations

(1) Preparation:Complete high voltage circuit breaker tripping, shutdown, and demagnetization operations prior to generator and control panel maintenance.

(2) Disconnection of isolation:Using a circuit breaker to swing out totest locationmethod of disconnecting the circuit breaker from the bus.

(3) Grounding:Open the grounding operating door, close the grounding switch using the grounding operating handle, and observe the switchboard ground-closing indication.

(4) Swing out to service position:Continue to swing to the service position, open the cabinet door and disconnect the secondary plug. Use the special trolley to lock and then pull the circuit breaker to the trolley (Figure 11-12).
* Note: After completing the grounding, a high-voltage checker must be used to confirm that there is no electricity before carrying out maintenance.

Figure 11-12 Schematic diagram of high voltage circuit breaker pulled to service position

(5) Push-in operation:Utilize the trolley to push to the test position and close the cabinet door. Utilize the rocker to swing to thetest location(disconnect switch disconnected), depress the grounding operating door; utilize handleDisconnect the grounding switch.(confirmation indicator), continue shaking untilworking position(as in Figure 11-13).

Figure 11-13 High-voltage circuit breaker push-in operation

(6) Inspection:Verify that the switchboard indicators, high voltage switch status and position indications are consistent with the standby condition.

Second, the high voltage switchboard routine maintenance precautions

strictly prohibit
High-voltage switchboards are strictly prohibited to work with electricityAlways make sure that the equipment is not energized before working.
programs
Work in strict accordance with safety requirements: Place in test position → disconnect the disconnecting switch → discharge to earth. Restore the reverse order after repair.
defend
Must take proper safety precautions and use high-voltage insulated tools and protective equipmentThe person must be assisted by a person.The top guard of the switchboard is strictly forbidden to be approached by personnel.