Testing 3 phase motors
 

I am testing a couple of 3 phase motors I have acquired. I have a single
phase to 3 phase 3/4 hp rotary converter that generates the 3 phase field.
I have checked a couple motors but when I tested 2 Baldor motors I tripped
my fused switches. The first heated my switch red hot and the second turned
slowly then killed my FRS 5 fuses in my converter set up. Both were 2-3 hp
but I checked a different manufacturer 3 hp motor and it ran fine. So at
this point I need to get more fuses. I had the motors wired for low voltage
to match my 240 supply. I checked these wiring configurations thoroughly.

How do I test these 3 phase motors? I checked resistance between a 3 leads
and measured a couple of ohms each. No spikes.

Also, I am looking to use these 3 phase motors for an idler in a separate
rotary phase converter.
I have read about getting a balanced voltage. Would this be just measuring
the 3 voltages from the 3 different combinations of leads? What is a decent
balanced voltage supply - say for mills or lathes?

Thanks
Pal

Testing 3 phase motors
 

"Pal" wrote in message
news:HncIc.68899$XM6.28243@attbi_s53...
I am testing a couple of 3 phase motors I have acquired. I have a single
phase to 3 phase 3/4 hp rotary converter that generates the 3 phase field.
I have checked a couple motors but when I tested 2 Baldor motors I tripped
my fused switches. The first heated my switch red hot and the second
turned
slowly then killed my FRS 5 fuses in my converter set up. Both were 2-3
hp
but I checked a different manufacturer 3 hp motor and it ran fine. So at
this point I need to get more fuses. I had the motors wired for low
voltage
to match my 240 supply. I checked these wiring configurations thoroughly.

How do I test these 3 phase motors? I checked resistance between a 3
leads
and measured a couple of ohms each. No spikes.

Also, I am looking to use these 3 phase motors for an idler in a separate
rotary phase converter.
I have read about getting a balanced voltage. Would this be just
measuring
the 3 voltages from the 3 different combinations of leads? What is a
decent
balanced voltage supply - say for mills or lathes?

Thanks
Pal

Pal

You seem to be doing the testing of the 2 or 3 HP 3 phase motors properly.
If the motor is possibly faulty, maybe you can evaluate it by connecting a
12 VDC battery to any two of the leads to the 3 phase motor and test the
resistance to 'twisting the rotor shaft'.

If you want any additional assistance with your testing you are welcome to
E-mail me at home.

Jerry