phase monitor

[angryman]

in a typical 230vac 3-phase circuit with a motor contactor and overload and disconnect, where is a 3-phase monitor generally placed in relation to these items? I would guess before the disconnect, but I've guessed before on things.

 

[thewellguy]

I usually place it after the disconnect and before he contactor.

 

[itsmoked]

You want it where it can prevent the contactor from ever closing if the power is bollixed up.

So as thewellguy sez.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

There are some nice power monitors used by the refrigeration industry. Some models include three phase voltmeters, recording of the last 25 faults, phase reversal, phase loss, voltage unbalance, timing functions appropriate for a hermetic compressor, and additional connections on the load side of the contactor to detect open or high resistance load contacts.
respectfully

 

[angryman]

cool thanks.....I leftit in before the contactor on the input basically because it fit nicely in my drawing there

Thanks for the comments!

Mark

 

[jraef]

There is an argument to be made for putting it ahead of the disconnect switch (with it's own separate disconnect and fuse protection). If the starter disconnect / breaker is interlocked with the enclosure door, the monitor may record every door opening as a phase loss (depending on it's internal power supply configuration). If you have one that does not have a fault buffer, you may lose the trip indication when you open the door to read it.

JRaef.com
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