HT LT Control Panel

Busbar and Cable Chamber Maintenance

• Isolate and discharge panels before commencing the job. 
• Measure the insulation resistance of incoming cable & bus separately.
• Inspect insulation on any outbound feeder cables & wiring.
• Check the bus bar’s support insulators for cracks, deformation, color changes, stresses, and foreign material.
• Any insulation maintenance essentially entails keeping all insulating surface clean.  This can be accomplished by wiping down insulating surfaces with a dry, lint-free cloth or paper towel.  
• Clean the collected dust (or) moisture on epoxy resin post insulators with a soft, dry cloth, and refresh as needed.
• To remove stubborn dirt, use a mild solvent (or) distilled water if wiping is ineffective. However, before using the surfaces, ensure that they are completely dry.
• Inspect contacts and remove any dust deposits. If the contact surfaces are rough, treat them with fine emery paper. Use a thin layer of petroleum jelly as needed.
• Ensure mounting screws & nuts are tight & connections are properly aligned.
• Check insulators for tightness. Do not put additional stress on the insulators. (They may crack.)
• Inspect bus bars and chambers for wear and damage. Clean as needed with plate polish. Check the bus bar’s connecting bolts for tightness.
• Inspect wiring & terminations for discoloration from heat, exposed conductors, and loose connections.
• Inspect control & power cabling terminations for discoloration from heat scorched or exposed conductors, and loose connections.
• Ensure air vents are not clogged.
• Check CT scans for any abnormalities.
• Ensure CT secondary neutrals are properly earthed.
• Determine the IR and continuity of the anti-condensation (space) heater. The resistance of space heaters must fall within the limits provided by the vendor.
• Verify the earth connections for safety & tightness.
• Use a 2500V megger to measure & record insulation values for each panel’s bus bar & out-going cables.

Breaker and Meter Compartment Maintenance

• Inspect switches for proper operation and internal components, including fuses and terminals.
• Check fuse connections for tightness and correct rating. Renew the fuse as needed. 
• Inspect control fuses for CTs and PTs. Check the fuse holder for overheating and ensure that the fuses are of the correct rating.
• Clean dust from panel and verify for proper sealing. 
• Ensure each circuit labels are appropriately connected to their respective panels.
• Inspect and test the draw-out mechanism, lubricate as needed, and ensure smooth operation.
• Inspect and test the safety shutters mechanism to ensure smooth & proper operation.
• Inspect breaker wiring for evidence of overheating and damage. 
• Ensure that every connection are tight and secure.
• Check the Line and Bus -PTs for any abnormalities. 
• Earth the secondary neutrals of Line and Bus-PTs.
• Inspect, clean, and test all auxiliary devices, including relays, contacts, and control transformers.
• Inspect the breaker and panel mounted limit switches.
• Check & clean earth & auxiliary contacts. Check that all connections are tight and secure.
• Measure insulation. Resistance of the main and control circuits.
• Ensure proper operation of all indication flags and lamps.
• Clean and lubricate all door hinges and locks.
• Manually operate protection devices and monitor for tripped breakers.

HT Panel Maintenance 

• Clean the panel both within and externally.
• Check control and power connections for tightness.
• Inspect lugs and cables for signs of overheating.
• Ensure tightness of the main busbar & coupler.  
• Examine earthing for tightness.
• Ensure the panel is vermin-proof.
• Inspect heater and thermostat performance.
• Check ON/OFF and emergency push buttons. 
• Use a 5 KV Megger to measure the I.R. value of the bus bar. (Phase to Earth & Phase to Phase) Before removing the Bus and Line PT/PT fuses. 
• After Meggering, insert the PT/PT fuses. 
• Test the electrical ON/OFF & spring charging of the breaker at the TEST position.
• Test the mechanical on-off & spring charging of the breaker at the TEST position.