Main switchboard Operation and Handling Procedure

First time operating a LV main switchboard

Look up on the MSB room entrance for CO2 indicator lamp colored RED and GREEN.
If GREEN lamp lite up, it safe to enter the MSB room, because the CO2 system is NOT ACTIVATED.
If the RED color lite up, you shall not enter the MSB room as the CO2 Extinguisher System is ACTIVATED.
Ensure the room is always lock.
The electrical switchboard room shall kept clean and no storage of any item inside the room.

Obtain switchboard schematic diagram and room layout diagram.
Get ready following test equipment such as multi-meter, insulation resistance tester or 'meggar'.
Standby tools such as testpen, screw driver, torch lights and other.
Wear PPE such as rubber gloves, safety shoe, safety glass and other relevant safety aspects.
Record all the technical information and ensure technical information is matching with the main switchboard. Example current transformer information is correct match with schematic diagram.

Open all MSB panels (front and back panel) and perform visual inspection inside MSB.
If see any foreign object inside the MSB quickly remove any object example such as hand tools, foreign objects. If found any pests have it remove. and if dusty perform cleaning work first.
Ensure all wiring on is secured on terminal and check if any missing or abnormal wiring found.
Ensure all sub main cabling works is done (from MSB to SDB) cables is secured and no cables are left hanging or not supported according to requirement.
Secure all bolts-nuts inside the MSB busbar and check and tighten all MCCB terminals for any loose termination.
Labeling and color to identify each busbar inside the MSB is check and noted.
Ensure all earth conductor and connected to earth are checked and confirm secured to the main earth terminal (MET).
Seek/request cleaner contractors to perform final clean in the electrical room before next step.

Before perform tests, ensure all main isolator and outgoing circuit breakers (mccb) are switched OFF and any fuse is to be removed.
Perform continuity test on every each MSB’s busbar.
Polarity test on MSB’s busbar.
Perform Insulation resistance test on MSB’s busbar. Set voltage 500 v and test duration at least 1~2 minute. Expecting results to be >1 MΩ.

How to perform insulation test, click here.

Perform functional test of main isolator to ensure operation is smooth flow of the breakers (ACB/MCCB).
Ensure testing result value is acceptable and all tests are to be recorded into main switchboard room log book.
Ensure the earthing system is been tested with acceptable value is <1Ω .

Ensure all panels open earlier are closed and secured.
Check if SESCO incoming supply is available/present by looking at power indicator light on EFR and OCR.
Inform management/boss that you are going to energize the MSB. (For insurance purposes.)
Inform anyone near MSB to step back or go outside the room.
If some people is around get their attention and do not to touch the any part of the MSB.
Final checking on all the outgoing circuit breaker (mccb) is OFF or TRIP position.

Ensure all outgoing MCCBs is OFF position. Put any fuse or circuit breaker back to CLOSE position.
Look at main isolator confirm OFF position.
Confirm SESCO supply is present looking at OCR/EFR power indicator lamp.
Press RESET button on both EFR and OCR to clear any fault may have stored in the memory.
Begin energizing the MSB by perform spring charge on ACB type breaker, after done then switch ON .

*For MCCB main isolator, there is no spring charge procedure required.

Look at the supply indicator lamp, ensure all are lite up and working.
Check voltage supply for single phase and three phase and each phase and R-Y-B by operating the voltage selector switch.
Wait at least 30 min in-case of any fault detected on the EFR and OCR.

Before switch ON other outgoing circuit breaker to sub distribution board (SDB) check and verified that all the MCCBs and SDB is correct according to layout/schematics. Ensure cabling works is secured and supported along the entire route from MSB to all SDBs.
Check at SDB on main isolator (mccb) is secure connected and switched OFF.
Perform Insulation Resistance Tests 'meggar' on outgoing breaker on its cables on MCCB. Ensure IR test results is acceptable.
Switch ON the MCCB of SDB, have some one to verify supply is present at correct SDB with the same labeled in the schematic diagram. If the sub distribution board is energized at MSB, verify supply is availabel at SDB main isolator/mccb.
Before continue to switch ON next MCCB other SDB, if some SDB cabling work is NOT YET DONE, place Tag or notice on MCCB outgoing breaker. No one shall switch ON the mccb with approval from competent person.
The last breaker is to switch ON the capacitor bank system.

Write/record all tests results value or any faults encounter into MSB’s log book with complete date/time and name of competent person.
Wait at least 30 minute outside the switchboard room for reason of in-case have sudden fault trigger.
Inform management/boss that the main switchboard is ENERGIZED.
After time reach, proceed to switch off room lights and lock the switchboard room.
Any defects spotted in electrical switchboard room must inform management and authority.