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07-17-2005, 02:58 PM #1
I got a NOS Leeson 2hp 3 phase motor and a Toshiba 2hp rated VFD. The VFD is specified to run on 230V single phase input and provide 7.5amps variable frequency output.
I'm fine with low voltage stuff, but an a little paranoid about working with high voltage (read deadly) electricity, plus I don't want to damage anything.
The motor has ten wires coming out of it. I got a basic wiring diagram (which I ould email to anyone interested in looking at it. The motor is rated 230V or 460V. On the diagram it indicatesthat for high voltage L1 (electrical leg I think)goes to T1, L2 to T2 and L3 to T3 and then notes to join and insulate three additional pairs of wires. For low voltage (my application), it indicates L1 to T1,T7, L2 to T2,T8 and L3 to T3,T9 and then join and insulate T4,T5,T6.
Does this mean to wire two wires as specified to each of the three output terminals on the VFD and then twist the other three together with a wire nut? What's the 10th wire for? Ground?
The wires coming out of the motor are all steel stranded. Is #10 solid core a good choice to use between the VFD and motor?
Anyone in the neighborhood want to make a couple quick bucks? (this sstuff makes my skin crawl).
It will be fed from a dedicated 20 amp circuit. Is that enough? Also, how large an input cable do I need from the wall to the VFD?
07-17-2005, 04:50 PM #2
Here's a schematic for the windings of your motor:
For low voltage operation (230 VAC), you are correct. Connect motor leads 1 and 7 to output line 1 on your VFD, 2 and 8 to output line 2, and 3 and 9 to output line 3. As you say, twist together lines 4, 5, and 6 and cap them off with a wirenut. What is the 10th wire labeled? It should say somewhere what it is connected to. If you think it might be a ground, check for continuity between the wire and the chassis of the motor. If you still can't figure it out, I would just tape it off, and ground directly to the chassis.
As for the wire, # 10 is overkill between the motor and VFD. #12 or #14 should be fine. A 20 amp breaker should be enough, and you will need to feed the VFD with #12.
Don't be too concerned about wiring, it's not that difficult. A piece of advice, however, is to always trip the breaker before you do any wiring. Always work on a dead circuit.
07-17-2005, 04:55 PM #3
I was wrong. there's 11 wires. The two extra are marked P1 and P2 and the Leeson diagram notes them as STATS(?).
The Toshiba notes that for single phase supply, to connect to two specific terminals. Does this mean to conect the two legs that read 240 across them? Then what about the third wire (neutral or common)that reads 120v when checked against the other two?
07-17-2005, 08:18 PM #4
The input side of the VFD only uses the two hot legs of the 220 volt single phase circuit. Do not use the neutral white wire for anything. There should be a place to connect the green ground wire. Your manual will tell you which terminals to connect the input side (incoming power) to. On my VFD, as I recall it is L1 and L2. On the output side (three phase) connect three wires and again there should be a ground connection. Some motors have only three hot wires and a ground and some have the neutral wire.
This all assumes you have a four wire 220 volt system. If your house or shop wiring is older three wire (two hot and a ground) there will not be a white neutral wire at all.I am not an electrician, but have seen in other posts, that the ground wire is not always green. I guess the ground could be white, so you need to look at how many total wires you have on the single phase input side.
In the past, I have been told to connect the ground wire to the motor frame and not depend on the chassis to made a good ground connection to the motor.
This is pretty basic wiring, but if you are truly uncomfortable, then get someone to help you out. I understand the anxiety issue.
07-17-2005, 09:00 PM #5