Discrimination

[atm84]

You have hit the nail on the head Darkwood. I agree, this subject is not taught enough. Many thanks for your advice. I agree, the main concern is discrim against my final circuit device and sub main device, which I have managed to achieve.

In regards to tenders, I agree. I really do wonder how many contractors do actually carry out full discrimination checks and then 'just hope for the best'

 

[GEOFF S]

I am using Amtech software and I am having trouble trying to achieve discrimination between a 100 amp SPN MCCB (Schneider TM-D) and a 200Amp BS88 in a TPN Switch Fuse.

Anyone else had this problem and know how to sort it. I can only achieve discrimination if I change the mccb for a 63 Amp one but that isn't what I want really. It's serving a submain circuit.

Hi

What is the max fault level at the MCCB, id be surprised that discrimination can not be achieved.

Cheers

 

[atm84]

It's not just energy based discrimination but time based too

 

[GEOFF S]

It's not just energy based discrimination but time based too

Hi

So you are using time cascade and current based discrimination? Anyhow what are the fault current levels?

Cheers

 

[atm84]

Yes both discrimination. Fault current levels (based on the generic 16kA at the incomer) there is a fault current of 12kA at the mccb