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How to maintain LV power distribution cabinet?

Dec 29, 2016

1. Purpose and Times

To make sure the safety operation of LV power distribution switchgears and equipment control cabinet.

2. It is applied for low voltage power distribution cabinet. The control cabinets of equipment should follow the relative items.

3. The maintenance department should do complete maintenance once half a year and finish the maintenance work in a short power-off time.

2. Content:

1. Preparation

a. Inform users one day before power off for maintenance.

b. Prepare the tools and finish maintenance work in a short power-off time.

2. Procedures

a. Main section by section. First maintain security load section.

b. Cut off the power of security load section, for others, still power on. Open the air switches of security load power supply, open air switches of generator. Turn the selection switch to OFF, dismantle the positive and negative wire of battery and mark to prevent supplying power to generator.

c. Check if the connection parts of busbar is deformed, if there is power discharging trace or black. Tighten the connecting bolts, change it if there is rust to make sure the connection is well. Check if the insulation of busbar is loose and damaged.

d. Rotate the main air switch from power distribution cabinet by handle. Check if the main contactor has burning trace, if the arc-distinguish shield is burned to black and damaged. Tighten the bolts of wiring, clean the cabinet and test mechanical ON/OFF.

e. Take out the switches from the drawer cabinet, tighten the wiring terminals. Check the installation and wiring of CT, ammeter, kilowatt-hour meter. Check the operational mechanism of handle is flexible. Tighten incoming line and outgoing line of air switches, clean cabinet and rear side outgoing line of power distribution cabinet.

f. Open the main switch of capacitor when maintain capacitance cabinet. Use 10MM2 leading wire to discharge power of capacitor to ground. Check contactor, capacitor wiring bolts, grounding device. Clean the cabinet.

g. Start generator to supply power to security section after maintenance. Cut off power of main busbar section to maintain.

h. Open the air switches at low voltage side stage by stage and then open CB at HV side of transformer. Close grounding switch and put mark “forbid closing switch, people are working”.

i. After maintain power distribution cabinet according to c, d, e, f requirements, dismantle safety device, open HV side grounding switch, close vacuum CB. Supply power to LV power distribution cabinet stage by stage after observation the normal operation of transformer and then supply power by commercial power supply from generator power supply. 

3. Precautions

1. Test the electricity after power off.

2. Install isolation device between power-off power distribution cabinet and live power distribution cabinet.

3. Wear insulation shoes and insulation gloves when open HV side VCB and there is supervisor.

4. Forbid touching before discharging power of capacitor to ground when maintain capacitance cabinet.

5. Check if there is left tools inside cabinet before supply power after maintenance. 

4. Relative documents and record

1. Maintenance work permit.

2. Maintenance record of power distribution cabinet and control cabinet.

3. Maintenance record of equipment