3 phase rotary converter only supplying half lathe speeds

capnahab · Aug 28, 2016

I have a 15 HP rotary converter for a lathe with a 7.5 HP motor. The lathe has push button motor start - 2 buttons, slow and fast for the motor. Starts very well on slow but I am limited to about 380 rpm ( it's a 17 inch lathe - in the UK ). The lathe is capable of double that on 'fast' motor speed. If I start up using the fast button It seems to overload the boost light which flickers and chatters. Starting in slow and then hitting the fast button does nothing. I would have thought the power of the converter would handle it.I know almost nothing about 3 phase. The converter was professionally installed to the shop and has a 60 amp supply as specified. The converter info is here
http://www.powercapacitors.co.uk/wp...erter_installation_operating_instructions.pdf

johnoder · Aug 28, 2016

Its common to have a two speed magnetic starter for a two speed motor. This consists of a PAIR of mechanically interlocked mag starters in an electrical enclosure. Sounds like the high speed side has some issues

JST · Aug 28, 2016

Also, double check that the machine controls are wired to the incoming lines, and NOT to the generated leg. It's bad practice and often leads to chattering controls.

The Transwave literature mentions that it is not designed for continuous duty. That suggests it may be a bit weaker on output, which may indeed cause it to be unable to start the high speed very well (despite the load being only 7.5 HP), and almost surely means it will drop out the controls due to low voltage if they are connected to the generated leg.

capnahab · Aug 30, 2016

Ok ,thanks Guys.
Johnoder - think you are right,
JST - I think they mean 24/7 by continuous.

So I have spoken to Transwave. Had my multimeter in the cabinet. The supply to the converter and the converter itself are fine. The voltage drop on turning on both fast and slow is negligible. The suggestion is that the phase wiring from the converter into the machine is the problem. I enclose a picture of the electrical cabinet. I need help from someone who can walk me through testing how to change the 3 phases.

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3 phase rotary converter only supplying half lathe speeds

capnahab

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JST

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capnahab

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