Torque1st
Aluminum
- Joined
- Nov 25, 2006
- Location
- KC Metro, KS
I have a 3Ø 7,5HP 220VAC 20.2A 60Hz 1710RPM motor VOEST lathe that will probably draw 18-20A at full load due to the voltage ratings. Startup will see a ~10% increase in required current. I am planning on a few more smaller 3Ø machine tools (mills etc) in my one man home shop. My air compressor and welder are single phase.
I am considering a RPC using a 10HP idler motor with friction drive 1/2HP pony motor starter with momentary start/run switch, no voltage correction caps. Connecting 1Ø 240-250VAC line L1/L2 with size 2 contactor with 120V coil from L1 for drop out protection and E-stops. Fed thru #6AWG from a 60A breaker in a 100A 1Ø 4-wire sub panel in my shop. The service panel for the house is 200A.
L1 L2 and manufactured L3 connected to a 3Ø 5-wire distribution panel with breakers for individual machines. A 40A (if possible) breaker will be used for the lathe.
1- My question is would it be better to have a theoretical 3600RPM or 1800RPM motor for the idler? Would the 3600RPM motor have more momentum to help with starting/reversing the lathe motor? Should the idler motor be as close to theoretical speed as possible?
2- Also has anyone ever used a relay powered from the wild/manufactured leg to drop out the main contactor if the idler motor stalls? Or would that cause too many false trips? The 60A main breaker would trip if it stalls anyway.
Thanks for any insight!
I am considering a RPC using a 10HP idler motor with friction drive 1/2HP pony motor starter with momentary start/run switch, no voltage correction caps. Connecting 1Ø 240-250VAC line L1/L2 with size 2 contactor with 120V coil from L1 for drop out protection and E-stops. Fed thru #6AWG from a 60A breaker in a 100A 1Ø 4-wire sub panel in my shop. The service panel for the house is 200A.
L1 L2 and manufactured L3 connected to a 3Ø 5-wire distribution panel with breakers for individual machines. A 40A (if possible) breaker will be used for the lathe.
1- My question is would it be better to have a theoretical 3600RPM or 1800RPM motor for the idler? Would the 3600RPM motor have more momentum to help with starting/reversing the lathe motor? Should the idler motor be as close to theoretical speed as possible?
2- Also has anyone ever used a relay powered from the wild/manufactured leg to drop out the main contactor if the idler motor stalls? Or would that cause too many false trips? The 60A main breaker would trip if it stalls anyway.
Thanks for any insight!