KYN28 high-voltage switchgear refers to electrical products with a voltage level of 12kV, which are used for switching, control or protection in power generation, transmission, distribution, power conversion and consumption of power systems. They mainly include high-voltage circuit breakers, grounding switches, mutual inductors, etc. The high-voltage switch manufacturing industry is an important part of the power transmission and transformation equipment manufacturing industry, and occupies a very important position in the entire power industry. Debugging is generally a routine process to test the safety and stability of equipment before replacing components or putting equipment back into use after a failure. This article summarizes the relevant issues for description.

一、                First, we briefly introduce the high-voltage switchgear to understand the corresponding precautions.

High-voltage metal-enclosed switchgear consists of two major parts: the cabinet and the trolley. The cabinet is divided into four independent compartments by metal partitions: busbar room, circuit breaker trolley room, cable room and relay instrument room. Trolleys are divided into circuit breaker trolleys, metering trolleys, isolation trolleys, etc. according to their uses. Trolleys with the same parameters and specifications can be freely interchanged. The trolley has a test position and a working position in the cabinet, and each position has a device in place to ensure reliable interlocking. The high-voltage switch cabinet has a safe and reliable interlocking device that can meet the "five protection" requirements:

               1. Prevent misoperation of circuit breakers;

               2. Prevent the disconnector from being pulled or closed under load, i.e. prevent the trolley from being pushed or pulled under load;

               3. Avoid hanging the grounding wire while it is energized, that is, avoid closing the grounding switch while it is energized;

               4. Prevent power supply with grounding wire, that is, prevent power supply when the grounding switch is in the grounding position;

               5. Prevent accidental entry into live compartments.

 The circuit breaker can only be closed and opened when the circuit breaker trolley is in the test or working position, and the trolley cannot move after the circuit breaker is closed, preventing the circuit breaker from being pulled or pulled out by mistake under load.

Only when the grounding switch is in the open position can the circuit breaker trolley be moved from the test position to the working position, and only when the circuit breaker trolley is in the test position can the grounding switch be closed, thereby preventing the grounding switch from being mistakenly closed when energized and preventing the circuit breaker from being closed when the grounding switch is in the closed position.

When the grounding switch is in the open position, the lower door and the rear door cannot be opened, preventing accidental entry into the energized compartment.

When the circuit breaker is in the working position, the secondary plug is locked and cannot be pulled out. To ensure safety and the reliability of each interlocking device without damage, the operation must be carried out according to the interlocking anti-misoperation procedure. 

2. Seven steps of power supply operation of main power cabinet 

1.            Close all cabinet doors and rear panels and lock them.
           2.            Push the transfer trolley and position it, push the circuit breaker trolley into the cabinet and position it in the test position. When pulling the circuit breaker, press the two push-pull handles of the circuit breaker to the middle and push forward (into the cabinet) with force. After the circuit breaker reaches the test position, release the push-pull handles and the handles should automatically reset. Manually insert the aviation plug, close the trolley room door and lock it. 
           3.            Observe whether the instruments and signal indicators on the upper cabinet door are normal. (When normal, the integrated relay power indicator is on, the circuit breaker opening indicator and the energy storage indicator are on. If all the indicators are off, open the upper cabinet door and confirm whether the busbar power switches are closed. If they are closed and the indicators are still off, the control circuit needs to be repaired.) 
           4.            Insert the crank handle of the circuit breaker trolley into the crank handle socket and press it down hard, turn the crank handle clockwise for about 20 turns, and remove the crank handle when it is obviously blocked and accompanied by a "click" sound. At this time, the trolley is in the working position, the aviation plug is locked, the main circuit of the circuit breaker trolley is connected, and the relevant signals are checked. (Because the main power supply and the backup power supply are mechanically interlocked, when the main power circuit breaker is in the working position, the backup power circuit breaker must be in the experimental position) 
           5. Observe the live display to confirm that the external power has been delivered to the cabinet. (The light on the live display panel indicates that the external power has been delivered to the lower contact of the circuit breaker of the cabinet. If the live display light is not on, the external power must be delivered to the cabinet first.)
           6.            Close the transfer switch to close the circuit breaker and supply power. At the same time, the red closing indicator light on the instrument door is on, and the green opening indicator light is off. Check other related signals. Everything is normal and the power is successfully supplied. (When operating the opening and closing transfer switch, turn the operating handle clockwise to the closing position indicated on the panel. After releasing the hand, the operating handle should automatically reset to the pre-closing position.)
           7.            If the circuit breaker opens automatically after closing or during operation, it is necessary to determine what kind of fault it is and eliminate it before re-energizing according to the above procedure. (When the circuit breaker opens due to a line fault, an audible and visual alarm will sound, that is, the red fault indicator light on the panel will light up, and the fault sound on the signal screen will sound. At this time, observe the integrated relay. If the protection trip light is on, the fault is line overcurrent. When repairing the fault, press the reset button on the signal screen to cancel the sound. After the repair is completed, press the reset button on the integrated relay panel to manually reset the integrated relay.)

3. Five steps for power outage operation of the main power cabinet 

1.            Observe all cabinet-related signals and confirm that all outgoing cabinet circuit breakers are in the open position.  
           2.            The transfer switch opens the circuit breaker to cut off the power. At the same time, the red closing indicator light on the instrument door goes out and the green opening indicator light turns on. Check other related signals. Everything is normal and the power outage is successful. (When operating the on/off switch, turn the operating handle counterclockwise to the off position indicated on the panel. After releasing the handle, the operating handle should automatically reset to the pre-off position.) 
           3.            Insert the crank handle of the circuit breaker into the crank handle socket and press it down hard. Turn the crank handle counterclockwise for about 20 turns. When the crank handle is obviously blocked and accompanied by a "click" sound, remove the crank handle. At this time, the trolley is in the test position, the aviation plug lock is released, open the trolley room door, and manually disengage the aviation plug. (The main circuit of the trolley is disconnected) 
           4.            Observe the power display and confirm that it is not powered before continuing the operation. (The lower door of the incoming cabinet is locked with an electromagnetic lock. It can only be unlocked when the incoming end is not energized. However, it can also be unlocked with a key when the incoming end is energized. The opening of the incoming circuit breaker does not mean that the incoming cabinet is not energized. If the external power supply is not stopped, the cable room is energized with high voltage at this time. Forcible entry is life-threatening.) 
            5. Open the lower door, test the electricity (must be tested), discharge (must be discharged), and hang the ground wire (must be hung with the ground wire). Maintenance personnel can enter for maintenance and inspection.

Fourth, the operation procedure of the standby power supply cabinet is the same as that of the main power supply cabinet. Since the relevant content has been introduced before, that is, the seven steps of power supply operation and the five steps of power outage operation, we will not repeat them.

V. Three steps of metering cabinet operation

1.            The metering trolley is directly connected to the moving and static contacts, and does not have the breaking and arc extinguishing capabilities. The metering trolley must not be shaken in and out with load.
              2.             The metering trolley and the incoming switch cabinet circuit breaker have electrical and mechanical interlocking. The metering trolley can be shaken in or out only after the main power supply (backup power supply) circuit breaker is opened. Do not force the operation to avoid damaging the interlocking device. When the metering trolley is forced out with load, the main power supply (backup power supply) circuit breaker will automatically open to avoid personal injury.
              3. The method of shaking in and out the metering trolley is the same as that of the circuit breaker trolley.

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Six, three steps of PT cabinet operation

1.            First, shake in the PT trolley.
           2. Observe the live display. If the display light is on, the 10KV high voltage has been delivered to the cabinet. Check whether the voltage meter shows normal.
           3. The method of shaking in and out the PT trolley is the same as the circuit breaker trolley.

VII. Seven steps for power supply operation of the outgoing line cabinet

1.            Close all cabinet doors and rear cover plates, and lock them. (The lower door of the cabinet can be closed only when the grounding switch is in the closed position) 
      2. Insert the operating handle of the grounding switch into the hexagonal hole on the lower right side of the middle door, rotate it counterclockwise to put the grounding switch in the open position, remove the operating handle, and the interlocking plate at the operating hole will automatically rebound to cover the operating hole, and the lower door of the cabinet will be locked.  
           3. Push the transfer trolley and position it, push the circuit breaker trolley into the cabinet and position it in the test position. (When pulling the circuit breaker, press the two push-pull handles of the circuit breaker to the middle and push them forward (into the cabinet) with force.)             After the circuit breaker reaches the test position, release the push-pull handles and the handles should automatically reset.) Manually insert the aviation plug, close the trolley room door and lock it.  
           4.            Observe whether the instruments and number indications on the upper cabinet door are normal. (Under normal circumstances, the integrated relay power indicator is on, the circuit breaker opening indicator and energy storage indicator are on, and the grounding opening indicator is on. If all the indicators are off, open the upper cabinet door and confirm whether the busbar power switches are closed. If they are closed and the indicators are still off, the control circuit needs to be repaired.)  
            5. Insert the crank handle of the circuit breaker trolley into the crank handle socket and press it down hard. Turn the crank handle clockwise for about 20 turns. When the crank handle is obviously blocked and accompanied by a "click" sound, remove the crank handle. At this time, the trolley is in the working position, the aviation plug is locked, and the main circuit of the circuit breaker trolley is connected. Check the relevant signals.  
           6.            Operate the closing and opening transfer switch on the instrument door to close the circuit breaker and supply power. At the same time, the red closing indicator light on the instrument door is on, and the green opening indicator light is off. Check the live display and other related signals. Everything is normal and the power supply is successful. (When operating the closing and opening transfer switch, turn the operating handle clockwise to the closing position indicated on the panel. After releasing the hand, the operating handle should automatically reset to the pre-closing position.)   If it cannot be closed normally, check whether the transformer door is closed.
           7.             If the circuit breaker opens automatically after closing or opens automatically during operation, it is necessary to determine the type of fault and eliminate it before re-energizing according to the above procedure. (When the circuit breaker is tripped due to a line fault, an audible and visual alarm will sound, and a fault sound will sound. At this time, observe the integrated relay. If the protection trip light is on, the fault is line overcurrent. After the inspection is completed, press the reset button on the integrated relay panel to manually reset the integrated relay.)

VIII. Six steps for power outage operation of the outlet cabinet

1.             Operate the closing and opening conversion switches on the instrument door to open the circuit breaker and cut off the power. At the same time, the red closing indicator light on the instrument door goes out, and the green opening indicator light is on. Check other related signals. Everything is normal and the power outage is successful. (When operating the on/off switch, turn the operating handle counterclockwise to the off position indicated on the panel. After releasing the handle, the operating handle should automatically reset to the pre-off position.) 
           2.            Insert the crank handle of the circuit breaker into the crank handle socket and press it down hard. Turn the crank handle counterclockwise for about 20 turns. When the crank handle is obviously blocked and accompanied by a "click" sound, remove the crank handle. At this time, the trolley is in the test position, the aviation plug lock is released, open the trolley room door, and manually disengage the aviation plug. (The main circuit of the trolley is disconnected) 
           3.            Push up the transfer trolley and lock it, pull out the circuit breaker trolley to the transfer trolley, and move the transfer trolley away. (When pulling the circuit breaker, press the two push-pull handles of the circuit breaker to the middle, and pull them back hard (outside the cabinet) at the same time. After the circuit breaker is pulled to the transfer trolley and in place, release the push-pull handles, and the handles should automatically reset.) 
           4. Observe the live display and confirm that it is not live before continuing the operation.  
           5. Insert the grounding switch operating handle into the hexagonal hole on the lower right side of the middle door, and rotate it clockwise to put the grounding switch in the closed position. After confirming that the grounding switch is in the closed position, open the lower door of the cabinet and maintenance personnel can enter for maintenance and inspection.  
           6.              The grounding switch, circuit breaker and cabinet door are interlocked. The grounding switch can be closed or opened only when the circuit breaker is in the test position or pulled out of the cabinet. The circuit breaker can be moved from the test position to the working position only after the grounding switch is opened. Do not force the operation. The grounding switch and the door under the cabinet are interlocked for emergency unlocking. Emergency unlocking can only be performed when necessary, otherwise there is a risk of electric shock.

IX. Relevant contents of electrical and mechanical interlocking

1.             Main power supply and backup power supply
            The main power supply (backup power supply) circuit breaker is equipped with electrical and mechanical interlocking. The two circuit breakers cannot be closed at the same time. When the main power supply circuit breaker is in the working position, the backup power supply can only be in the experimental position and cannot be closed. The same applies in reverse.
           2. Main power supply (backup power supply) circuit breaker and metering trolley
           The main power supply (backup power supply) circuit breaker can only be closed when the metering trolley is in the working position. After the circuit breaker is closed, it is not allowed to swing out the metering trolley with load. If the metering trolley is pre-swung by mistake, the circuit breaker will trip immediately and the signal screen will alarm.
           3. Outgoing line cabinet and transformer
             The outgoing line cabinet and transformer are equipped with electrical interlocking. The outgoing line cabinet can be closed only when all the transformer doors are closed. If one of the doors is not closed, or all doors are not closed, the outgoing line cabinet cannot be closed.
           4. The circuit breaker of the outgoing line cabinet is connected to the