Genset MCCB Tripping

The main factor seems to be the lack of knowledge of the workman regarding this specific gen set.

Have you consulted the troubleshooting guide in the operator's manual?

Have you called, or communicated with Cummins?

Have you commissioned a Cummins repairman to come fix it?

Have you commissioned a local electrician to fix it?

I had consulted the troubleshooting guide when using the MCCB first time.

How do you know that the load is 9 KVA? This load is too small to trip a 100 A MCCB. Measure the current.

Ditto.

Correct trouble shooting procedures should sort this out easily enough.

Hope the OP heeds advice and provides feedback.

Thanks to 'whoever it is' for the GA.

100 amps MCCB is not the right choice What is the setting set in the MCCB Was there any sudden load put on to the set? The full load current of the set is more than 100 amps

due to loose connection. check all point of contact. wheather the circuit hav short circuited or not check that...

binod panthee

electrical engineer

Nepal Eletricity Authority,Butwal regional office,Butwal,Nepal.

Dear,

The tripping of MCCB can happen due to varying reasons,

- over current (not the reason here & hence eliminated)

-Deration of breaker due to high temp (check the temp, rare chance)

-Settings on the MCCB (various parameters can be st on the MCCB under which it should trip, this include instantaneous, short circuit, earth fault) These need to be reviewed and make proper settings- Mainly this could be the reason.

- Improper earthing at generator end.

-Earth & neutral continuity from source to load & tightness.

Hope this will solve your issue, kindly update...

cheers..

We need more information about this problem because if you are simply switching from utility supply to genset supply and you have 220vac at the genset then it sounds impossible.

Can you tell us how you are changing over from genset to mains and what protection you have before the 100amp MCB both at the mains and at the genset. How is the 100amp MCB wired for mains operation? Have you a two pole changeover switch so that there is no connection to the mains when the genset is in service?

Also are you calculating your 9kVA from an ammeter reading at the genset. Are you sure that 220vac is maintained?

What kind of load are you supplying, lighting, heating, motor loads. A motor load will take more current on undervoltage, so a reduced voltage at the genset may cause an increase in current but you would see this at the genset ammeter.

At a guess I would think you have only a single pole changeover arrangement and there is some neutral or earthing current tripping your MCCB. If possible temporarily switch off all the mains connections and isolate the genset from any external neutral earthing, create a single new earth connection at the genset and try again....alternatively make new connections with the genset isolated similar to a portable genset going directly to the load with no possible link to any part of the installation. If this cures your problem you need to check how the changeover arrangement is operating.

Personally I would leave the genset 100amp MCCB and arrange a changeover to supply the load through a second 100MCCB from the mains supply, i.e. the changeover swith is on the load side of the supplies.