Transwave converter

[Michael CallaghanParticipant @michaelcallaghan68621]

Hi, I have a Colchester bantam lathe, for years I have been running the 3phase motor with the German inverter that came with the lathe. However the inverter died and I needed to replace. I purchased a used 2kw transwave converter off eBay. The lathe motor is rated for 1kw. Today I hocked it all up, but the motor is making a lot of noise. And the transwave setting switch even at setting 1 shows a very high amp draw. Is my understanding of how these things wrong correct, ie the converter will only produce power related to motor demand, so over powering the motor can’t happen. I have not yet reinstalled the motor casing. But before ido it would be nice if someone can let me know if I am killing the motor or not. By using a larger converter then motor rating.

[Michael CallaghanParticipant @michaelcallaghan68621]

[larry phelan 1Participant @larryphelan1]

Dont know, but I use a 7.5 kva unit to run my 1.5 hp lathe.

Of course it also runs my 4.5 hp planer or spindle moulder.

Dont see how it could do any harm, but just a thought, are you sure the converter is big enough ?

I think you may need something a bit bigger.

[Michael CallaghanParticipant @michaelcallaghan68621]

Hi, thanks for getting back. The transwave unit is rated at double the motor rating, so should be ok. It must be just me not ever hearing the motor not boxed in.

[SillyOldDufferModerator @sillyoldduffer]

Have you tried the other 'power' settings? There's only a rough relationship between switch position and motor size, so it's worth experimenting. I'm not familiar with the transwave but I think the voltmeter measures the fake phase and should read about 240v. If it's not, the motor is being fed unbalanced 3-phase, which might explain noise.

Other possibilities: Static converters have a start mode that's switched off once the motor is running by a relay. They can go wrong, perhaps not cutting out. Also, the circuit depends on capacitors that can fail.

One important thing to check: make sure the motor isn't getting hot! A mismatched static converter can burn out the motor. If the motor warms up, don't use it until the problem is resolved.

Any Transwave owners or converter experts about?

Dave

[ManofkentParticipant @manofkent]

My 3hp lathe motor ran happily fir many years from a 2 hp rotary converter!

It is worth changing the wire to terminal connections around and see if that helps.

Also a 3 ph motor makes a horrible noise when wired in delta with only two of the phases connected!

John

[Chris Evans 6Participant @chrisevans6]

I've run a Transwave static inverter for about 8 years now. It powers my 3hp lathe ok but would not run the 2hp Bridgeport mill for more than a few minutes. Never did sort out why and fitted a VFD to the mill.

With the lathe running I turned the setting knob to show around 400 volts on the meter and have not touched it since. On odd occasions the motor will sound "Wrong" powering down and back on again restores normal service. Only downside I can think of with the inverter is no soft start. Every now and again the lathe starts with a bit of a sudden clonk, does not seem to have done any harm though.

[EmgeeParticipant @emgee]

Michael

If you haven't had it very long you could contact the seller and let him know there is a problem with you motor when powered by the inverter, was it listed as good working order ?

Emgee

[not done it yetParticipant @notdoneityet]

Posted by John Hilton on 08/09/2020 21:22:23:

My 3hp lathe motor ran happily fir many years from a 2 hp rotary converter!

It is worth changing the wire to terminal connections around and see if that helps.

Also a 3 ph motor makes a horrible noise when wired in delta with only two of the phases connected!

John

It might also draw a lot of current if it is wired delta instead of star? Just wondering what the VFD and converter voltages might be… If the current indication is correct – and it is high for the motor – the motor will not last long.

[SteviegtrParticipant @steviegtr]

Not used one of those but is the output from them not 400v ish. In which case would the motor need to be put to star.

Steve.

[Robert Atkinson 2Participant @robertatkinson2]

+1 for motor being wired delta instead of star (220-240V instead of 380-415V).

You can't harm anything by trying it wired for star so tht is the next step.

Robert G8RPI.

[Michael CallaghanParticipant @michaelcallaghan68621]

Thanks chaps. Had a look at a second bantam running off a transwave and the noice is the same. I think that part of the problem is I alway ran the lathe at low revs. With the transwave it’s a lot faster, so more noice. I think I will return to the German inverter if I can find one. Thanks again.

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