MCCB TRIPS ON GENERATOR SWITHOVER

[alok10]

We have 63amp type C MCCB on input of 15 KVA UPS. This MCCB frequently trips when power supply is switched from main to generator or from generator to main (Auto switching). Kindly suggest should we use type D MCCB to solve this problem or there is any other solution. Expert advice on topic will be appriciated.

 

[JohnD]

does the switch break first then make?

what is the load? is there a motor, welder, furnace, X-ray machine or what? Air con? refrigeration?

 

[alok10]

load is approx. 6 KVA and all are computer equipments like servers, storage and network equipments. 30 KVA generator is installed for data center and apart from UPS 3 nos. 3.5T air conditioners are also connected to this generator. when main power supply goes generator starts automatically and stops when main supply comes back. MCCB trips while this switching is happening.

 

[bongos]

It's probably due to the inrush of current with all those items switching back on together. While a D-type MCB may cure the problem you should first make sure all your earth fault loop impedance reading (or Indian equivalent) are within spec for a D-type.