Hi

Does anyone know the maximum ZS value for a BSEN60947-2 MCCB, I have been asked to do a quote for some works following a peridic. The switch is 125A and the report say it should have a MAX ZS of 0.15 which seem very low. It is reading 0.30 Ohms.

I can't say for certain but considering a 32a B type mcb is 1.44 ohms 0.15 doesn't sound too unbelievable does it?

Try here for schneider otherwise ring the manufacturer.
http://pws.schneider-electric..../MGD5032_section2.PDF/

-------------------------
Regards

Dave(not Cockburn)

You will need manufacturer's data; many of these devices also have adjustable characteristics. What make is it?

-------------------------
http://www.niceic.biz

As others have said, it sounds beleiveable as IM works out to being roughly equal to 125Ax12, and 12 seems a common multiplyer used in these things. However as others state, its quite possibly adjustable in which case you can wind the 12x down.

125A BSEN60947-2 will be 0.30 @ 100% value..... go back to installation and tighten terminals etc then redo the loop..... you maybe lucky enough to get a lower reading.

Definitely use manufacturer's data. 0.3 Ω looks high and should be assessed in more detail. Most devices range between 0.15Ω and 0.23Ω at full setting; generally 10x to 12x In, for instantaneous operation.

-------------------------
http://www.niceic.biz

I would agree with Keith here - 0.3 ohms suggests a multiplier of 6, which is pretty low for a (probably) fixed thermal magnetic unit for operation under 0.1 seconds.

A multiplier of 6 suggests operation stated at 5 seconds so a thermal check on conductor thermal protection would be in order

Regards

OMS

-------------------------
Failure is always an option