Wiring motor for SB Lathe

I have a old SB Lathe cat# CLC 155C sn# 8090HKX 12 finally getting around to wiring it up
motor tag only list High voltage or Low voltage and says its 3 phase
it does not tell me what voltage or amperage it should take
the wires on the motor are connected together for high voltage
I ran 3 phase 480v on 20 amp breaker to a 10amp fused disconnect switch
started it ran correct forward and reverse direction then heated up one of
the 10amp fuses change out and replaced with 15amp fuses thinking it
needed more power but then it tripped 20 amp breaker

it has a Furnace J2 drum switch wired correctly it use to run when I bought it
how much amperage and voltage do these motor require to run ?

Typically 480 is high voltage, 208 is low voltage.

Whats the horsepower on the motor? 1.5 hp at 480 is about 2.5 amps full load but the startup surge is probably about double that. If you're blowing a 10 amp fuse, either there is something wired wrong or the motor has issues. You really should have overloads on that in addition to fuses. Overloads will open with a phase loss before the fuse will. Often the motor will roast before the fuses let go.

The common voltages for a 3 phase industrial motor would be 230/460 volts or 220/440. Sometimes 208 volts is supplied and sometimes 575. It's hard to know what's appropriate for your motor without some sort of tag on the motor. Typically, the motor leads are not colored, particularly on older motors but have metal tags crimped on or ID's printed on the leads and there should be a diagram someplace on the motor showing how they should be connected. Just because it looks like it's hooked up for high voltage doesn't mean it's done correctly.

If you can find out who made the motor you might be able to get a correct diagram if there isn't one on the motor. If all else fails, I would separate out all the winding leads and start checking coil resistances. If all is well with the motor, all of the coils should have the same resistance but you still won't know how to hook them up unless you also know the polarity of the coils. You could determine that by applying a small DC current to each set and checking the magnetic polarity with a compass needle. But you're talking about a pretty tedious job to sort that all out and you'd need to do careful bookkeeping to make sure you have it all straight.

From your description I would conclude that either the motor has one or more defective coils or they are not hooked up properly. If your time is worth anything, you'd probably be time and money ahead to just replace the motor and get on with life.

You should use "Tony's law" ...The last guy who touched it had a bad day....Assume it was not done correctly and pull the motor out so you can see what you are doing and verify the wiring.

If someone wired it wrong it will do what it is doing.

Best to check for wire labels and if none then get a label maker or colored tape and label each wire and document how it is now wired then tear it all apart to where you only have single wires then check all with ohmmeter to frame for shorts and to other wires to determine each winding.

Hopefully with the motor out you can find something to identify it.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

Pretty much agree with all of the above. My version dumbed down for me:

Your highest amps is always at motor start up, that's why you need a bigger breaker than rated amps. Also an unloaded motor, sitting on the floor will pull less amps than the same motor when hooked to a machine and working.

Generally for American 60hz voltage: Low voltage 208-240. High voltage 440-480.

Actual amps depends on HP and voltage. There are actual math equations, as well as charts you can google, hp, kw, and such. Any given motor will pull roughly twice the amps using low voltage, verse what it would using high voltage.

I would double check your actual incoming voltage, if you have not. A 3 phase motor may have 9 leads coming out. Each wire should have a paper or metal tag, 1-9. Separate them all. Take your ohm meter and check resistance between each wire and the motor case, it should be a big fat zero, or no reading. If there is a reading, than a coil is shorted to ground, and bad.

Still using the ohm meter, check each wire against every other wire. I'm thinking you'll come up with 3 pairs of wires that read resistance, not a zero, or dead connection, but like a 8-15 ohm resistance. That is one wire reading resistance to one other wire, 3 pairs this way. And three wires not reading to anything, so totally 9.

If all good, wire for your correct incoming voltage and try again.