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Message No. 16362, Started by gerdb on 06/30/05
I have an electric motor that draws 220 volt 3 phase 20 amp (vacuum pump for air).  It keeps on blowing the circuit breaker within seconds of start up.  What is the minimum amp required for the circuit breaker ?

that is the answer I am looking for, but I am also curious about what the answer would be for a single phase motor ?

Thanks in advance

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Follow-up Messages (14)
I have no actual experience with this, but if I recall my electronics from ...
No. 16404, Posted by rorschach on 07/05/05, 13:53 PST.
Sam: simple question for you... What equipment/methods/procedures are used...
No. 16395, Posted by rolschwarz on 07/03/05, 05:50 PST.
Did you review the website I referred to earlier? It explains a lot. Agai...
No. 16394, Posted by rolschwarz on 07/03/05, 05:40 PST.
What is a "controller" ? My idea whould be to go with a 140 amp breake...
No. 16393, Posted by gerdb on 07/02/05, 21:36 PST.
Ooh, can't believe I blew that. V = I*R --> I=V/R. More resistance still ...
No. 16392, Posted by rolschwarz on 07/02/05, 18:07 PST.
Ohm's law is: V = I*R, so it looks to me like you got the impedance on the ...
No. 16391, Posted by sdoughty11 on 07/02/05, 15:47 PST.
Anyhoo, Gerd, the short answer to your question is that a bigger breaker or...
No. 16390, Posted by rolschwarz on 07/02/05, 13:11 PST.
Hmm.. let me think... Ohm's law... current = voltage * impedance... By y...
No. 16389, Posted by rolschwarz on 07/02/05, 11:27 PST.
Rolschwarz: You are way off base. I have not forgotten Ohm's law at all...
No. 16386, Posted by sdoughty11 on 07/01/05, 18:53 PST.
for the "Google imapired":
No. 16385, Posted by rolschwarz on 07/01/05, 18:38 PST.
You're forgetting Ohm's law. More resistance = less current @ same voltage....
No. 16384, Posted by rolschwarz on 07/01/05, 18:05 PST.
Rolschwarz: This effectively reduces the voltage across the motor until suc...
No. 16383, Posted by sdoughty11 on 07/01/05, 14:28 PST.
Some old plants had motors with special resistors that were placed in the c...
No. 16380, Posted by rolschwarz on 07/01/05, 10:51 PST.
Gerdb: The starting current for an across the line start on a 3 phase motor...
No. 16371, Posted by sdoughty11 on 06/30/05, 17:03 PST.
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