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Multilple 3 phase motors.


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I had a major problem with multiple motors on a wood working machine today.

3 seperate unrelated faults all contributed to a massive machine failure.

First fault diagnosed was the overload protection set too high for the motor ratings.

Second fault was both motors where linked to a single motor break.

Third fault was down to a lost phase.

An electrician before me had replaced the overload with a new one but could not get the machine to work and gave up.

When I got there one motor had burned out and because of force feeding had blown one of the phase fuses (rewirable).

The other motor had no overload protection because it was smaller than the one that had blown, so in turn that overloaded and burned out.

I had to replace both motors,and the overload whilst set too high and was replaced when tested proved to be ok, and was replaced by the original electrician when there was no need to.

The moral of this story is to test, its the only way to find the underlying problem, fix that and you are on the way to solving simple problems, not creating more problems.

The factory thought I was a genious lol.

All I did was test it out and they ended up with some spares.

I wonder what I should charge for being a genious? ROTFWL

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You have nothing to declare but your genius. (Wilde) My mate Bob the Breakdown is also a genius, he charges

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fault finding can be hard at times. spent 4 hours earlier trying to find a fault thats tripping main RCD. DB1 feeds most of the place and also DB 2 & 3. DB2 has an IR of 0.02 L/N - E testing from DB1, so start there. when a certain RCBO is turned on and appliance are plugged in, main RCD trips, yet all outgoing circuits from DB2 are over 5M ohms. turns out to be a fault on a socket circuit in a different part of building fed from DB3

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