fuse and overload

[angryman]

sorry if this is posted, I'm sure it probly is, but didn't find anything...
I've inherited a bunch of drawings of which part are motor control cktry...typical input power-motor contactor-overload however, they all have fuses on all 3 phase wires before the contactor/overload. I knwo NEC says each phase wire must be fused, but is that in addition to the overload? Why?

 

[Skogsgurra]

Fuses are for short-circuit protection. Overload is for thermal protection - like what you have when lifting a too heavy load or pumping too much water.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[motorsdirect]

In short....fuses protect the mains supply and your overloads protect the motor!!

Jeff

http://www.motors-direct.co.uk