Digest, Vol 21, Issue 26 Msg # 6 Motor Controller

SVCatITC at aol.com SVCatITC at aol.com
Sat Jul 29 00:30:37 EDT 2017

A motor controller, above 1 hp, and usually used on a 3 ph line, is a  
glorified relay.
It however has, added features of thermal cutouts on each of the phases on  
the load
side of the relay.  It's normal electrical name is a contactor.   The 
actuating coil is 
usually 120 VAC, however it can be in special cases 24 VAC or 24 VDC.
Some of the reasons it is used is:
1.  To start all 3 phases at the same time to the motor.
2.  Provide (in some cases) a local START / STOP pushbutton  station.
3.  Provide trip protection in case of overload or stall of the  motor.
4.  Allow remote START / STOP capabilities / facilities.
They are usually big and bulky because the contacts are rated to  handle 
high horsepower inductive current ratings. They also must make  and  break 
the circuit 
quickly to quench the arc over so as not to weld the contacts  together.
More questions about this topic are welcome.
Bill Inderrieden
In a message dated 7/28/2017 12:16:23 P.M. Eastern Daylight Time,  
vcf-midatlantic-request at lists.vintagecomputerfederation.org writes:

Message:  6
Date: Thu, 27 Jul 2017 19:14:27 -0400
From: Evan Koblentz  <evan at vcfed.org>
To: Vcf  <vcf-midatlantic at lists.vintagecomputerfederation.org>
Subject: Re:  [vcf-midatlantic] Museum power / Running bigger machines
Message-ID:  <11095b74-0b91-4f41-9828-84e6b181650c at vcfed.org>
Content-Type:  text/plain; charset=UTF-8

>> Maybe Martin will provide one to us  but I didn?t ask. I found one on 
Amazon for  $142.00

Well  you just posted on the public list which he reads, too. :)

Anyway:  what's a magnetic motor  controller?

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