Thread: electric motor fun

Hi Mike,

Couple of questions..

Does the motor turn over by hand?
What frequency did you have set for the output?
How was the motor wired?
Did it trip on over current or earth leakage?

Get an electrician and have the motor insulation and windings checked, before going any further.
A rewind would be around $300-$400 at a guess, it's usually on a par with new motor cost, a second hand 3hp motor would be possibly a lot less, depending on how much work is involved in fitting it.

Regards
Ray

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Originally Posted by RayG

Hi Mike,

Couple of questions..

Does the motor turn over by hand?

Yes it turns over freely Ray , no binding .


What frequency did you have set for the output?

60 hz as its a USA motor , it says 60 hz on the ID plate

How was the motor wired?

DELTA , I checked this carefully , and rechecked it a few times .

Did it trip on over current or earth leakage?

Well , the earth leakage definately tripped . Would this indicate poor insulation in the stator ? I initially thought the VFD had shut down , but thinking about it , the earth leakage device must have cut the power off .

Get an electrician and have the motor insulation and windings checked, before going any further.

I tried to get a loan of a MEGGER , but I couldn't find one around here . Ok it might save some money by paying 50 bucks to have it checked out by a sparky .

A rewind would be around $300-$400 at a guess, it's usually on a par with new motor cost, a second hand 3hp motor would be possibly a lot less, depending on how much work is involved in fitting it.

OK , I will think about getting it rewound .

Regards
Ray

Mike,
Just to give you an idea, I bought a new 3hp, single phase TECO motor some years ago for my hammer. This is no POS, it must weigh 40-50kg, and has (from memory) a 26mm shaft. It was just over $500 i think. Its about 3 times the size of the supposed 3hp motor on my air compressor.

Ewan

Originally Posted by Ueee

Mike,
Just to give you an idea, I bought a new 3hp, single phase TECO motor some years ago for my hammer. This is no POS, it must weigh 40-50kg, and has (from memory) a 26mm shaft. It was just over $500 i think. Its about 3 times the size of the supposed 3hp motor on my air compressor.

Ewan

Ewan

Yes this old GEC motor I have would weigh about that , or a bit more I think .

The shaft on it is 1 and 1/8" diameter , a real odd ball size these days . And, the shaft is long, to take the wide 3 belt B section V pulley

TECO might be worth looking at , I will do a search MIKE

Hi Mike,

Pull the motor out, and take it to the local motor rewinding place, and ask them to check it out for you, while you're there, get them to check that you've hooked it up correctly for 240V 3phase. The symptoms you've described sounds like it's hooked up wrong..

They will tell you if it's insulation or something else, just a check out shouldn't cost too much, and once that's sorted you can move ahead with the other stuff.

Whenever I'm firing up a motor for the first time on a new machine, I always start at low frequency, 5hz or so, and check rotation direction etc... when you've got the motor back and are about to crank it up, just set the VFD to 5Hz and get the basics right, like rotation direction, any mechanical issues etc etc ... then progressively move up.

Regards
Ray

Hi Mike,
Do you have PD004=60?

Stuart

Hi morrisman,
this motor, did you pull the star point out yourself? thought you(maybe someone else recently) pulled the star point out of the windings to rig it up for delta. If it was you then you could have the windings sequenced wrongly.

I would second RayG, get it to a rewinder, if you did the star point pull get them to check the windings sequencing first up,(they'll megger it first though) then on from there. Best wishes with it.

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.

Originally Posted by Stustoys

Hi Mike,
Do you have PD004=60?

Stuart

Hi Stuart

Yes I had PD004 on 60hz , the base frequency of the motor ..right

I will take it to the experts..there is a motor rewind service locally ... I will see what he has to say . But the cynical part of me says : I think he's just an agent and he sends the work out to be done . Naturally , he will recommend to rewind it , as its more $ for him ..I might wait til the next trip into the big smoke ... and keep my options open MIKE

Originally Posted by Log

Hi morrisman,
this motor, did you pull the star point out yourself? thought you(maybe someone else recently) pulled the star point out of the windings to rig it up for delta. If it was you then you could have the windings sequenced wrongly.

I would second RayG, get it to a rewinder, if you did the star point pull get them to check the windings sequencing first up,(they'll megger it first though) then on from there. Best wishes with it.

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.

HI LOG

Yes that was me , that was the motor on the Indian made T&G grinder . That motor runs fine on the VFD .

The Hendey motor is past its prime , the insulation looks OK but its probably iffy , the cotton has likely rotted . Not many 72 year old people function like new . MIKE

Originally Posted by morrisman

HI LOG

Yes that was me , that was the motor on the Indian made T&G grinder . That motor runs fine on the VFD .

The Hendey motor is past its prime , the insulation looks OK but its probably iffy , the cotton has likely rotted . Not many 72 year old people function like new . MIKE

Ah yes, the T&G grinder, I remember now

Cheers.

If I'm not right, then I'm wrong, I'll just go bend some more bananas.

Originally Posted by morrisman

Hi Stuart

Yes I had PD004 on 60hz , the base frequency of the motor ..right

I will take it to the experts..there is a motor rewind service locally ... I will see what he has to say . But the cynical part of me says : I think he's just an agent and he sends the work out to be done . Naturally , he will recommend to rewind it , as its more $ for him ..I might wait til the next trip into the big smoke ... and keep my options open MIKE

It really does not matter what frequency you have it set at..eg 50, 60 or 40 for that matter..the frequency just dictates the max speed availablA usa motor although rated at 60 will run just fine at 50 just a little slower...same as a 50hz rated...it will run just fine at 60 but at a higher rpm than the rated 50

sounds like you may have stuffed up with your connections.

. Not many 72 year old people function like new . MIKE

Boy ain't that the truth.

Robbo37

Originally Posted by eskimo

It really does not matter what frequency you have it set at..eg 50, 60 or 40 for that matter..the frequency just dictates the max speed availablA usa motor although rated at 60 will run just fine at 50 just a little slower...same as a 50hz rated...it will run just fine at 60 but at a higher rpm than the rated 50

Hi eskimo,
Not so.
The frequency setting we are talking about is used to calculate some sort of Hz v voltage ramp. So as I understand it, if you have PD004=400 when the VSD is running at 50Hz, instead of having 240V you will have 30V*................... or something like that. A bare motor will turn at 30V but you can stop it with your foot.

PD005=max Hz
Stuart

*borrowed from Ray who can likely explain it much better than myself.

Originally Posted by Stustoys

Hi eskimo,
Not so.
The frequency setting we are talking about is used to calculate some sort of Hz v voltage ramp. So as I understand it, if you have PD004=400 when the VSD is running at 50Hz, instead of having 240V you will have 30V*................... or something like that. A bare motor will turn at 30V but you can stop it with your foot.

PD005=max Hz
Stuart

*borrowed from Ray who can likely explain it much better than myself.

Hi Stuart
I am refering to the point that the motor nameplate says 60Hz. I would not have thought this relevent/important to the setting of the VSD. In other words the motor should work just fine if the VSD was set for 50Hz....Ray ..where are you?...whats your opinion