I bought a used RPC and plan on using the motor for a home built RPC. The RPC is made by Cedarberg Industries. The motor plate has been removed, as well as the labels on all the capacitors in the panel. The only label on it states max motor size is 7.5HP, so I assumed it had a 15HP motor. Turns out it's 10HP. I'm not using the Cedarberg unit as is because it has a toggle switch that has to be turned on and off when starting the RPC. I want to put the RPC in another room and use a 3 wire start/stop circuit at the machine to turn the RPC on and off.
I made a test board to build the RPC before installing it in a panel. One start button powers the mag starter for legs 1 and 2, the other start button is a momentary switch for the start capacitors on leg 3.
When I finished the board I connected a 3HP motor I had laying around to make sure things were good before wiring up the 10HP motor. I connected one start cap (430-516 UF) on the L3 circuit to start the 3HP motor and it started fine. I measured 242v/193v/213v across the output legs, so all was good. I moved onto the bigger motor.
I bought new start capacitors, one 430-516 UF and two 630-750 UF, so a total of 1,690-2,016 UF, to start the 10HP motor (judging by the size of the start caps, the Cedarberg unit used three 630-750 UF caps). I started the 240v circuit, the motor started spinning, then I briefly pressed the start cap circuit button, maybe a 1/4 of a second. The motor started to spin a little faster, but it didn't spin up to full speed. I hit the stop button, waited till the motor stopped spinning, and started it again. This time I held the cap circuit button a little longer, maybe a 1/2 to 3/4's of a second. The motor did the same thing, spun with 240v, spun a little faster when power was applied on leg 3, but it still didn't come up to speed.
I was concerned about damaging the motor by holding the cap circuit on too long, so I decided to test the motor windings before going any further.
A ground check on all 9 wires showed none of the windings were grounded.
Continuity tested as follows -
T1/T4, T2/T5, T3/T6 checked good, and all 3 showed the same 1.5 ohms
T7/T8/T9 did not have continuity between them in any combination
Then I checked it again and found the following wires had continuity between them:
T1/T4 and T9
T2/T5 and T7
T3/T6 and T8
Before I took them apart, the 9 wires were connected for 240v as follows
L1(A)- T1/T6/T7
L2(B)- T2/T4/T8
L3(C)- T3/T5/T9
So the motor is Delta, not Wye. I read on this forum and others that Cedarberg doesn't share specs on their RPC's, but I called anyway to ask about the Model 75 RPC I had. I was politely told they don't give out any info or specs, not even a wiring schematic. The only thing he told me was the Model 75 RPC has a 10HP motor, not 15HP as I thought.
So, my questions are -
Is the motor good? Should a Delta wound motor have continuity between T7/T8/T9 or is the continuity above the correct way a 'good' Delta should motor should be?
Should I be holding the cap start circuit on longer, until the motor is up to speed, before I release the button?
FWIW - the wires coming from the mag starter to the distribution block are 6 AWG, all the rest on the board are 10 AWG. The motor is wired with a 10' long, 4 wire, 12 gauge SOOW cable. It lighter wire than I'll use when wiring the panel, but I figured this would be fine for testing purposes.
If things work out I have questions about the proper contactors and relay I need, but obviously have to get the motor working first.
I made a test board to build the RPC before installing it in a panel. One start button powers the mag starter for legs 1 and 2, the other start button is a momentary switch for the start capacitors on leg 3.
When I finished the board I connected a 3HP motor I had laying around to make sure things were good before wiring up the 10HP motor. I connected one start cap (430-516 UF) on the L3 circuit to start the 3HP motor and it started fine. I measured 242v/193v/213v across the output legs, so all was good. I moved onto the bigger motor.
I bought new start capacitors, one 430-516 UF and two 630-750 UF, so a total of 1,690-2,016 UF, to start the 10HP motor (judging by the size of the start caps, the Cedarberg unit used three 630-750 UF caps). I started the 240v circuit, the motor started spinning, then I briefly pressed the start cap circuit button, maybe a 1/4 of a second. The motor started to spin a little faster, but it didn't spin up to full speed. I hit the stop button, waited till the motor stopped spinning, and started it again. This time I held the cap circuit button a little longer, maybe a 1/2 to 3/4's of a second. The motor did the same thing, spun with 240v, spun a little faster when power was applied on leg 3, but it still didn't come up to speed.
I was concerned about damaging the motor by holding the cap circuit on too long, so I decided to test the motor windings before going any further.
A ground check on all 9 wires showed none of the windings were grounded.
Continuity tested as follows -
T1/T4, T2/T5, T3/T6 checked good, and all 3 showed the same 1.5 ohms
T7/T8/T9 did not have continuity between them in any combination
Then I checked it again and found the following wires had continuity between them:
T1/T4 and T9
T2/T5 and T7
T3/T6 and T8
Before I took them apart, the 9 wires were connected for 240v as follows
L1(A)- T1/T6/T7
L2(B)- T2/T4/T8
L3(C)- T3/T5/T9
So the motor is Delta, not Wye. I read on this forum and others that Cedarberg doesn't share specs on their RPC's, but I called anyway to ask about the Model 75 RPC I had. I was politely told they don't give out any info or specs, not even a wiring schematic. The only thing he told me was the Model 75 RPC has a 10HP motor, not 15HP as I thought.
So, my questions are -
Is the motor good? Should a Delta wound motor have continuity between T7/T8/T9 or is the continuity above the correct way a 'good' Delta should motor should be?
Should I be holding the cap start circuit on longer, until the motor is up to speed, before I release the button?
FWIW - the wires coming from the mag starter to the distribution block are 6 AWG, all the rest on the board are 10 AWG. The motor is wired with a 10' long, 4 wire, 12 gauge SOOW cable. It lighter wire than I'll use when wiring the panel, but I figured this would be fine for testing purposes.
If things work out I have questions about the proper contactors and relay I need, but obviously have to get the motor working first.