simple fan motor wiring gone haywire?

[kurt s]

i have a trane unit ventilator with high and low speed for the fan.

should be a simple 115ac motor replacement, the problem is im having trouble understanding the wiring.

there are 5 wires (white, black, oragne, blue, red) one would think white is neutral, and the others are speeds but this is not the case.

for cw rotation red,blue must be jumped together..... white is hot (115v) and black and orange have either 18v for the high speed or 36v for low speed feeding them, depending if the switch is set at hig or low.

i have never seen this before, anyone else here have any idea how these work?

[Brian_UK]

Have you got a motor model number you could give us?

[Quality]

Above all motors fan motors are the best as there seems to be no standard

[monkey spanners]

Does it have a capacitor?

How was the original motor wired?

[kurt s]

thanks for the responses,
its a GE motor, it has a capacitor yes, model is skcp39eg S936 S

white is hot (115v) and black and orange both have either 18v for the high speed or 36v for low speed feeding both of them, depending if the switch is set at hig or low. the other 2 blue and red are jumped together.

i cant believe it but the white is hot wire, i thought it would be a neutral. it works fine but its driving me crazy:rolleyes:

[chilliwilly]

It sounds like a standard configuration of wiring colours for most North American blower motors, which are usually White = Common (neutral), Black = High speed, Yellow = Medium speed, Blue = Medium Low speed, Red = Low speed.

If you were to change the black for the hot and white for the neutral it would still work.

[kurt s]

chilliwilly

its not as simple as that, its wired 100% corectly the way i described. i was just looking to see if anyone else has run into this before. and get some input as to how this thing works.

all i know is its a TRANE motor specificly for that unit from TRANE. but its possible there are others like it.

ive just never seen a 115v simple little motor like this run the 2 speeds off of a low volatage transformer like it appears to do.

[Brian_UK]

Is it running off a transformer or using a wire wound resistor in circuit to effect speed change?

[Gary]

GE motor numbers start with 5 not S.

What is the Trane model number?

[kurt s]

my mistake model is 5kcp39eg S936 S

trying to get wiring diagram picture to load, having some trouble but ill keep at it.

[chilliwilly]

chilliwilly

its not as simple as that, its wired 100% corectly the way i described. i was just looking to see if anyone else has run into this before. and get some input as to how this thing works.

all i know is its a TRANE motor specificly for that unit from TRANE. but its possible there are others like it.

ive just never seen a 115v simple little motor like this run the 2 speeds off of a low volatage transformer like it appears to do.


This type of configuration is common in small and some larger multi speed/multi pole motors. Each of the motor leads can be either connected to tappings on transformers, or connected to a switch that will configure the windings to be in series or parrallel with the same voltage applied to any winding configuration.

Usually a three speed motor may have three windings, each winding will be wound around a pair of one or more poles in the motor stator. Or may have three windings wound around one pole, with tappings at different places in the winding. That will run at different speeds when lower to higher voltages are connected to them. But this kind of configuration will only give poor torque at the lower speeds, the latter will give higher torque at lower speeds and lower torque at higher speeds.

The only other alternative is a two pole motor connected to a VVF drive, but they can drive up the cost of the package.