Frank B
Plastic
- Joined
- May 23, 2007
- Location
- Manchester, England
I have an old 1hp dual voltage GE KC motor fitted to a 1951 Boxford lathe. The type number of the motor is 5KC48U0280X. The motor is a capacitor start, capacitor run type, but I cannot find technical information of any real value.
The only information I have found, apart from a few useful posts on the Practical Machinist forum, is that the KC type is described as an instant reversing type. The motor also has thermal protection.
The previous owner had tried to wire this motor up. But judging from the state of the wiring and the reversing switch, which was housed in a non-original housing, with evidence of shorting, things did not go well.
Among the problems I have is that the outside wiring connections on the board were obviously incorrect, so could not be followed. And the reverse side of the connection board has unidentified wires, and wires that are no longer attached to the board.
These stray wires, with the odd crimp and connector block poking out from under the board, were missing identification markings on the ends I could see. As all the wires are black, there is no help there with identifying them.
I also suspected there could be problems with the centrifugal switch, which turned out to be correct. I removed the centrifugal switch on the connection board, which allowed me to try to check the internal wiring somewhat.
The CS contacts were totally welded together. I managed to separate the contacts and stoned them reasonably flat again.
I managed to identify the two run windings that need to be connected in series for 240VAC operation, which is what I want. So I have T1, T2 and T3, T4, although the marks were only present on two wires. Both coils checked out around 1.2 Ohms, so appear not to have been fried.
I then identified the wires attached to the capacitors. Wire 19 runs from the NC start contact on the centrifugal switch to the cap, and the other wire from that cap, T8, goes into the motor body.
The other cap has wire 112 from the same tag feeding the CS, and the other cap wire is 111, which runs into the body.
The wire to the tag feeding both the CS and wire 112 is cut short, with a connector block and no ident. Not helpful.
I tried to identify a start coil, and found T5 connected internally to T8 giving 2.7 Ohms. But I also found T8 connected to the cap wire 111, giving 10.0 Ohms.
And measuring between T5 and 111 gave me 12.7 Ohms, an apparent summation of the two coil resistances.
Being confused, and wondering if this was some part of the “instant reversing” mechanism. I tried to figure out how to connect the motor to just act like a normal cap start, cap run motor, but failed.
I do not want instant reversing, mainly because the lathe has a screw on chuck, which I have no desire to wear!
I have read several very helpful posts, including some from Iron_junkie. But one post which showed the thermal protection switch to a very similar motor puzzled me as well.
This post shows P1 as a feed for the thermal switch, while my P1, which was connected to 3 on the TP, goes into the body of the motor, and appears to be a sensor only. As 1 on the TP is from the L bottom tag, P1 on this ancient motor does not appear to be a feed. Iron_junkie said for high voltage use, 2 on the TP was unused, but with what looks like a sensor on 3, and a power feed to 1, surely 2 must feed the coils etc?
Is there anybody out there who can help here? I had to break off playing with the motor some weeks ago to do jobs in the house etc. But now I have looked at it again, a VFD seems easier to handle! Best wishes to all, Frank B
The only information I have found, apart from a few useful posts on the Practical Machinist forum, is that the KC type is described as an instant reversing type. The motor also has thermal protection.
The previous owner had tried to wire this motor up. But judging from the state of the wiring and the reversing switch, which was housed in a non-original housing, with evidence of shorting, things did not go well.
Among the problems I have is that the outside wiring connections on the board were obviously incorrect, so could not be followed. And the reverse side of the connection board has unidentified wires, and wires that are no longer attached to the board.
These stray wires, with the odd crimp and connector block poking out from under the board, were missing identification markings on the ends I could see. As all the wires are black, there is no help there with identifying them.
I also suspected there could be problems with the centrifugal switch, which turned out to be correct. I removed the centrifugal switch on the connection board, which allowed me to try to check the internal wiring somewhat.
The CS contacts were totally welded together. I managed to separate the contacts and stoned them reasonably flat again.
I managed to identify the two run windings that need to be connected in series for 240VAC operation, which is what I want. So I have T1, T2 and T3, T4, although the marks were only present on two wires. Both coils checked out around 1.2 Ohms, so appear not to have been fried.
I then identified the wires attached to the capacitors. Wire 19 runs from the NC start contact on the centrifugal switch to the cap, and the other wire from that cap, T8, goes into the motor body.
The other cap has wire 112 from the same tag feeding the CS, and the other cap wire is 111, which runs into the body.
The wire to the tag feeding both the CS and wire 112 is cut short, with a connector block and no ident. Not helpful.
I tried to identify a start coil, and found T5 connected internally to T8 giving 2.7 Ohms. But I also found T8 connected to the cap wire 111, giving 10.0 Ohms.
And measuring between T5 and 111 gave me 12.7 Ohms, an apparent summation of the two coil resistances.
Being confused, and wondering if this was some part of the “instant reversing” mechanism. I tried to figure out how to connect the motor to just act like a normal cap start, cap run motor, but failed.
I do not want instant reversing, mainly because the lathe has a screw on chuck, which I have no desire to wear!
I have read several very helpful posts, including some from Iron_junkie. But one post which showed the thermal protection switch to a very similar motor puzzled me as well.
This post shows P1 as a feed for the thermal switch, while my P1, which was connected to 3 on the TP, goes into the body of the motor, and appears to be a sensor only. As 1 on the TP is from the L bottom tag, P1 on this ancient motor does not appear to be a feed. Iron_junkie said for high voltage use, 2 on the TP was unused, but with what looks like a sensor on 3, and a power feed to 1, surely 2 must feed the coils etc?
Is there anybody out there who can help here? I had to break off playing with the motor some weeks ago to do jobs in the house etc. But now I have looked at it again, a VFD seems easier to handle! Best wishes to all, Frank B