Hello all. First or second post here but I like the general feel of the Forum here (relaxed!) and look forward to learning and contributing.
I received my South Bend Fourteen (14x40) lathe about 4 years ago. It's the 1970's variable speed with variable pitch pulleys, not to be confused with the older 14 1/2" model. The lathe has a 3HP, 3-phase motor which runs (ran) off a Phase-A-Matic PAM-300HD static phase converter (SPC). The SPC is rated for 1-3HP and is the heavy duty model. The input to the SPC is 230V single phase off a 20A breaker. IS 230V weird? Each leg is 114-115V WRT ground at the outlet.
So the SPC worked ok for the first 4 years I owned it a presumably several years prior. The motor always buzzed for 5-10 seconds on start up. I figured that was the time needed for the motor to come up to speed and for the SPC to reliably generate the 3rd phase. Sometimes it buzzed longer than others.
Last weekend I was using the lathe and it was starting as normal, then on a start attempt, the motor buzzed but did not rotate. I found that if the lathe was in low gear, I could give the chuck a spin and the motor would slowly spin up to speed, then the buzzing would stop. This did not work in high gear.
I did a little voltage diagnostic last night. The way the lathe is wired now, L1 and L3 are the two 230V lines from the outlet and L2 is the 'generated' 3rd phase from the SPC. Before you wonder if the lathe is wired correctly or if the motor is mistakenly wired for 440V, the lathe has been working OK for the 4 years I've had it.
So, running (after I give the chuck a spin in low gear), the voltages at the lathe circuit panel are L1-L2 192V, L2 L3 226V, L1 L3 194V. Stopped the voltages are L1 L2 0V, L2 L3 227V and L1 L3 227V.
Further, when the lathe is trying to start with motor buzzing but not turning, voltages are L1 L2 108V, L1 L3 218V and L2 L3 110V.
The SPC has a light on the box that according to the instructions should go out when the motor is at operating speed. My light stays on all the time. Because its on the end of the lathe, I usually don't see it and can't say for sure about the light function in the past. The motor spins freely and does not seem to heat up more than I'd consider normal.
So I'm 70% sure the SPC is toast. Your thoughts? Although a VFD would be great, the variable speed function of the lathe works OK so its hard to justify the cost differential compared to a new SPC. Has anyone had experience with SPCs from ebay like this: http://tinyurl.com/9lp3c9q
Thanks for the help,
Paul
I received my South Bend Fourteen (14x40) lathe about 4 years ago. It's the 1970's variable speed with variable pitch pulleys, not to be confused with the older 14 1/2" model. The lathe has a 3HP, 3-phase motor which runs (ran) off a Phase-A-Matic PAM-300HD static phase converter (SPC). The SPC is rated for 1-3HP and is the heavy duty model. The input to the SPC is 230V single phase off a 20A breaker. IS 230V weird? Each leg is 114-115V WRT ground at the outlet.
So the SPC worked ok for the first 4 years I owned it a presumably several years prior. The motor always buzzed for 5-10 seconds on start up. I figured that was the time needed for the motor to come up to speed and for the SPC to reliably generate the 3rd phase. Sometimes it buzzed longer than others.
Last weekend I was using the lathe and it was starting as normal, then on a start attempt, the motor buzzed but did not rotate. I found that if the lathe was in low gear, I could give the chuck a spin and the motor would slowly spin up to speed, then the buzzing would stop. This did not work in high gear.
I did a little voltage diagnostic last night. The way the lathe is wired now, L1 and L3 are the two 230V lines from the outlet and L2 is the 'generated' 3rd phase from the SPC. Before you wonder if the lathe is wired correctly or if the motor is mistakenly wired for 440V, the lathe has been working OK for the 4 years I've had it.
So, running (after I give the chuck a spin in low gear), the voltages at the lathe circuit panel are L1-L2 192V, L2 L3 226V, L1 L3 194V. Stopped the voltages are L1 L2 0V, L2 L3 227V and L1 L3 227V.
Further, when the lathe is trying to start with motor buzzing but not turning, voltages are L1 L2 108V, L1 L3 218V and L2 L3 110V.
The SPC has a light on the box that according to the instructions should go out when the motor is at operating speed. My light stays on all the time. Because its on the end of the lathe, I usually don't see it and can't say for sure about the light function in the past. The motor spins freely and does not seem to heat up more than I'd consider normal.
So I'm 70% sure the SPC is toast. Your thoughts? Although a VFD would be great, the variable speed function of the lathe works OK so its hard to justify the cost differential compared to a new SPC. Has anyone had experience with SPCs from ebay like this: http://tinyurl.com/9lp3c9q
Thanks for the help,
Paul