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Topic Title: ZS value for BSEN 60947-2
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Created On: 04 April 2011 07:54 PM
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 04 April 2011 07:54 PM
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jamie123

Posts: 18
Joined: 24 January 2010

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.
 04 April 2011 08:08 PM
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daveparry1

Posts: 6169
Joined: 04 July 2007

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?
 04 April 2011 08:23 PM
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dg66

Posts: 1670
Joined: 11 January 2008

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

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Dave(not Cockburn)
 05 April 2011 11:13 AM
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kj scott

Posts: 2144
Joined: 02 April 2006

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

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 06 April 2011 08:30 AM
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Phoenix151

Posts: 77
Joined: 14 February 2007

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.
 06 April 2011 09:11 PM
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jaminben

Posts: 1
Joined: 06 April 2011

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.
 07 April 2011 09:48 AM
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kj scott

Posts: 2144
Joined: 02 April 2006

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.

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 07 April 2011 10:45 AM
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OMS

Posts: 19623
Joined: 23 March 2004

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

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OMS

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