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RPC Help Needed

Avanti

Cast Iron
Joined
Nov 13, 2003
Location
Wauna, WA
I just powered up the 1943 vintage Cincinnati 16" HD shaper that I have had sitting for about 6 months. It was a working unit when removed from service, I am told, and it is in very nice condition. It has a 5 hp 220/440 motor on it. I verified that it is wired for 220 volts.

My RPC is an Eyelander 10 hp (start 10 hp, run 20hp) that was set up to run a 5 hp 415 volt 50 Hz machine with a set of transformers, so it is a heavy load. I have been using it to power some 1 hp tools w/o problems. When I hit the on switch the motor ground to about 50 rpm and blew one of the cartridge fuses in the mag starter. I replaced all 3 and checked for mechanical trouble. The motor starts with only the load of the belts and the clutch pulley and spins freely, yet won't start. I don't have a good way to measure the amperage at this time, but the voltages unloaded are about 240 volts. Upon closing the contacts the voltage on T1 and T2 drops to about 225. The T3-T1 and T3-T2 voltages drop to about 135 volts as it is trying to start. No smoke or heat anywhere while it is trying to start. This RPC previously ran a 5 hp Quincy air compressor, although it would not reliably start it at full pressure with its broken unloader.

What next?
 
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Depending on your unloaded voltages, a better balance might help. Post the three idling voltages.

If the Lathe is OK, and you have a good balance, you may just need a larger RPC. One way to fake a larger RPC would be to try starting and idling some of your other smaller load three phase equipment, then starting your lathe. The motors in the equipment will effectively become idlers.

-Joe
 
I would start by...

Your 10hp RPC should be able to start a 5hp shaper... and with many hours already on the RPC, I'd highly doubt a problem there.

I would start by turning the shaper's motor by hand, and make sure it's not dragging... I wouldn't think that sitting 6 months would cause problems, but don't discount anything.

Next thing I'd do, is see if there's a way to disengage the shaper's motor from the machine (run it uncoupled).

I would try again, and see if it starts it up. If so, measure voltages running.
Before messing with balancing caps, etc., in your RPC, I'd pull the motor cover one-more-time, and make sure the #6 and #9 wires weren't swapped, as is #1 and #7... (been there!).
 
If the load motor is trying to turn over slowly, but won't come to speed, be sure
to verify that it really is wired for 240 volt service.

This is the exact behavior that my vacuum pump at work presented to me - slowly
turning rotor - when I was trying to run it on 208, when it was wired up for the
higher voltage.

Jim
 
The motor is wired for 220 volts. I wired in my 5 hp air compressor to use for extra idler capacity. I lit it off with no load on it and then the shaper motor started. After a bit it began to get warm on the pulley end bell. I pulled the oil cap for the bearings and lo and behold, a curl of smoke exited the hole. Once I lubed the bearing up it started fine. It seemed to spin easily with the dry bearing but under load of starting the friction must have been much higher. I would not have expected that such a small amount of drag would have made it not start. The air compressor starts with a significant load just fine,
 
I have to assume that this motor is a sleeve bearing, since there is a oil cap. With a bearing of this design, there should be alittle play in the shaft if I push the shaft in, but there should be no play at all on the shaft if I lift the shaft up and down or side to side.
If the bearing is bad, make sure that the shaft is not scored by the bearing.
 
At this point it is working fine, so I am disinclined to dig further. The bushings are probably fairly worn, but I don't need perfect at this point. Usually when things get taken apart, they stay that way for too long a time and I am having too good a time making big blue chips today to disable the machine. It is very quiet, so I suspect it is pretty low time. I sure do like the rapid traverse. Someone local wanted to buy it, but bailed when he got the idea that it had a broken gear gear in the feed mechanism. PO thought so, but it was just pilot error. Sure glad I did not sell it.
 
Avanti, I have a 20" cincinnati shaper with the orginal 5HP motor I run from a shop built 7.5HP RPC. If the temp. in my shop is below 60F it will not start the shaper. At 65 and above it starts and runs like new! This is not exactly the problem you have but you might try to warm the shaper up and then try starting with your RPC. (It takes a few hrs to heat up all that iron if your shop is cold)
Norm
 








 
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