Run 440 v 3 phase lathe on 240 v single phase?

I purchased a 1940 L&S 16 in lathe with 5 hp 3 phase motor. Hooked up 5 hp TEMCO static phase converter. It runs for about 30 seconds and thermal breaker trips. Pulled motor cover, appears to be wired for 440v. I can change the motor wiring to low voltage--except the wires are no longer labelled. How can I tell which wire is which? Also will going from a heater B 15.5 to a B 19.5 (square D)stop the tripping of the breaker? Thanks.
























i

The connections are not that hard. taking it as a 9 wire motor....

The motor will have 3 line connections, and a star point with 3 wires connected together that get no numbers. You may not even see that connection.

There will be 3 connections between 2 wires each.

if the line connections are arbitrarily labeled 1, 2 and 3, then.....

a) the wire that reads a connection with 1 when the 2 wire connection is opened is 4, and the one it was with is 7

b) the wire that reads to 2 is 5, and the one it was with is 8

c) the wire that reads to 3 is 6 and the wire it was with is 9.

d) for low voltage, connect 1 and 7, 2 and 8, and 3 and 9, and connect 4,5,and 6 together. Line goes to the 1/7, 2/8, and 3/9 pairs.

e) to restore to high voltage, if you want to ever, connect 4&7, 5 & 8, 6&9, connect line to 1,2,3

A static converter is not the best.

a 5 HP single phase motor draws 28A at 230V. The 15A should have held it, just, unloaded, but there are sometimes issues with static converters. 20A should let you get some work out of it, but may not let you do a lot.

Best would be a VFD or rotary converter.

I suppose there could be an issue with the converter, the motor, or stiff bearings, stiff belts, etc, that put extra load on even when idling.

sascher said:

Also will going from a heater B 15.5 to a B 19.5 (square D)stop the tripping of the breaker? Thanks. i

Click to expand...

Just where is this Square D "thermal breaker " located? Is the breaker in the electrical supply panel that supply power to your converter?

IF so it is probably connected to a 14 gauge wire that is rated for 15 amps. Changing it to a 20 amp breaker is not good practice as you need 12 gauge wire to carry 20 amps.

If the device that is tripping is in fact a heater connected to a magnetic switch substituting a 19.5 for a 15.5 will not be enough to stop it from tripping.

When you change voltages from 440 to 220 you also need to change the heaters. 440 requires about half the amps that 220 does. IF the heaters are 15.5 amps when using 440 volts you will need around 31.0 amp heaters for 220.

Help!

These are pics of the motor plate. I carefully dug through the dirt and grease and found 9 wires with labels 1-9. 1,2&3 were hooked to L1,L2,&L3. 4,5&6 were hooked together and capped. 7,8,&9 are individually capped and connected to nothing else. So, do I wire it like the plate says for a 6 wire and do nothing with 7,8&9 or wire it like a 9 wire and ignore the motor plate diagram. Thanks again, this 3 phase stuff makes this old man uncomfortable.
1&4, 2&5,and 3&6 have continuity as do 7,8&9. The plate says for low voltage to wire 1&6, 2&4, & 3&5 each to line-- What about 7,8,&9? Or do I wire 1&7, 2&8, and 3&9 each to line and combine 4,5,&6? Or 1,6,&7 to L1, 2,4,&8 to L2, and 3,5&9 to L3? HELP!