MCB Minimum Capacity

Hello tomy@sabtron.com

Please advise which MCB you need advice for:

1. Primary MCB
2. Secondary MCB
3. Both MCB's

Reply here, with

Hi tomy,

A 100A / 600V MCB would be adequate if the expected load is resistive, use at least a 200A / 600V MCCB otherwise.

regards

Hello again, tomy@sabtron.com

As per feridun above.

If you need Fault Discrimination in your arrangement, use a larger MCCB for the Primary, with a lower Amperage MCCB for the secondary.

Example: Primary: 100 AMP MCCB with Secondary 80 amp MCCB.

If magnetising current (Switch-on surge) trips either of the above MCCB's, then use: 160 Amp MCCB Primary, with 100 Amp MCCB secondary.

The use of a larger MCCB for the Primary, will ensure by (Discrimination against Cascade Fault), that if the secondary loading is too great, the Secondary MCCB will trip, leaving the Primary MCCB not tripped.

Kind Regards....