I recently replaced the 2hp single phase (230v 50hz) induction motor in my lathe as a result of the centrifugal switch on the old one fusing on and it being easier to find a replacement motor than the switch for an obscure chinese motor.
The problem i am having is wiring the motor up in reverse. The old motor was a 4 pole motor with a starter capacitor. Naturally because this is in a lathe it needs to have reverse controlled from the machine itself so it has 4 wires + earth from the machine to the motor:
Colour | Forward | Reverse
___________________________
BLACK | neutral | neutral
RED | live (230) | live (230)
BROWN | live | neutral
BLUE | neutral | live
Each wire was connected to one of the 4 terminals in the old motor.
The replacement motor we bought has 8 internal terminals as it has a start and a run capacitor.
(u1) X X (W3)
. x (U2)
(V1) X X (U3)
. X (V2)
(W1) X X (V3)
According to the inside cover the connections should be:
Forward U1,W3 & V1 LIVE. W1, V3 & U3 NEUTRAL
Reverse U1, W3 & U3 LIVE. W1, V3 &V1 NEUTRAL
The theory i worked on was connecting the permanant live( RED) to U1 & W3. Then permanent neutral to W1 & V3. Finally i connected (BROWN) to V1 and (BLUE) to U3 as these were the only connections that changed for forward or reverse.
This worked to a limited extent, forward works great! Starts up nicely and runs well, reverse is not so great. The motor hums and moves very slowly, giving it a spin and starting still makes a strange hum but it maintains the spun speed.
Could anyone help me work out what is happening here? The only thing i can think of is something to do with the capacitor configuration but i have not been able to find any reference to the capacitor connections. I would also appreciate a pointer to any good documentation on induction motor theory and connections?
Thanks
The problem i am having is wiring the motor up in reverse. The old motor was a 4 pole motor with a starter capacitor. Naturally because this is in a lathe it needs to have reverse controlled from the machine itself so it has 4 wires + earth from the machine to the motor:
Colour | Forward | Reverse
___________________________
BLACK | neutral | neutral
RED | live (230) | live (230)
BROWN | live | neutral
BLUE | neutral | live
Each wire was connected to one of the 4 terminals in the old motor.
The replacement motor we bought has 8 internal terminals as it has a start and a run capacitor.
(u1) X X (W3)
. x (U2)
(V1) X X (U3)
. X (V2)
(W1) X X (V3)
According to the inside cover the connections should be:
Forward U1,W3 & V1 LIVE. W1, V3 & U3 NEUTRAL
Reverse U1, W3 & U3 LIVE. W1, V3 &V1 NEUTRAL
The theory i worked on was connecting the permanant live( RED) to U1 & W3. Then permanent neutral to W1 & V3. Finally i connected (BROWN) to V1 and (BLUE) to U3 as these were the only connections that changed for forward or reverse.
This worked to a limited extent, forward works great! Starts up nicely and runs well, reverse is not so great. The motor hums and moves very slowly, giving it a spin and starting still makes a strange hum but it maintains the spun speed.
Could anyone help me work out what is happening here? The only thing i can think of is something to do with the capacitor configuration but i have not been able to find any reference to the capacitor connections. I would also appreciate a pointer to any good documentation on induction motor theory and connections?
Thanks