Motor wiring question

[eeprom]

Hello,
I bought a surplus 3 phase, thermally protected, 230/400 V motor (50 Hz). I didn't know it was 50 Hz when I bought it, but I'm not worried about that part of it, because 400V at 50 Hz will produce the same operating current as 480V at 60 Hz. I'm not clear on the motor leads. The motor leads are marked as: T1, T2, T3, 4, 5, 6, and there are also two black leads and a red lead.

I'm not a motor expert...but, I am assuming that T1, T2, T3 are the higher voltage connections, the 4, 5, and 6 are for parallel windings for the lower voltage connection, and the red is the hot leg of the thermal circuit breaker, and the blacks are NC and NO of the breaker. But..before I wire anything up, I'd like some advice on how this should be wired. And, if I were to use the 4, 5, and 6 leads, how would they be used?

thanks for your help
EE

 

[edison123]

What is the voltage and frequency you plan to run this motor ?

Muthu

http://www.edison.co.in

 

[eeprom]

480V at 60 Hz. I am using a vfd, so I can set it to 50 Hz, but I see no reason to.

I took a meter to test the leads.

Resistance from T1 to 4 is app 20 ohms
Resistance from T2 to 5 is app 20 ohms
Resistance from T3 to 6 is app 20 ohms

Red to one of the blacks is 0.1 ohms
Red to the other black seems to vary a little - 7 to 15 ohms. This resistance changes when I spin the motor with a drill. Could be a resettable fuse.

Seems to me that I wire 4 to T2, 5 to T3, and 6 to T1, and I have a delta. When I made that connection, I got app. 14 ohms across any two leads. I measured the delta connection on another 1/3 hp motor (this new one is also 1/3 hp) and I get 15 ohms between any two of the power leads.

 

[waross]

For the higher voltage (480V) you want a wye connection. Connect 4 to 5 to 6 and insulate. Apply the supply voltage to L1, L2, and L3.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[eeprom]

Please explain that non-intuitive answer. It seems that the wiring would be the other way around.

 

[waross]

The windings are 230 volt windings. (230/400V)
When 230 volt windings are connected in wye or star, the resulting phase to phase voltage is 230 x 1.73 (root three) or approximately 400 volts. Look at some motor manufacturer sites for IEC star/delta connections.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[eeprom]

"When 230 volt windings are connected in wye or star, the resulting phase to phase voltage is 230 x 1.73 (root three) or approximately 400 volts."

I guess I am missing something very fundamental, because this statement seems out of place. Of course the phase to phase voltage is sqrt(3) times the line to neutral voltage. This property of three phase electricity is not dependent on the motor.

Given that there is a voltage supply of 480V, wiring the motor in a wye, each phase would have 277V across it. If the windings are wired in a delta, each winding sees 480 volts. I've read enough of your posts to have confidence in your reply, but I guess I don't understand this one. Please tell me what would be wrong with wiring the motor as a delta and using a 480V supply?

 

[waross]

Smoke. The motor is a 230/400V motor. The windings are each, individually 230V rated. They are connected in delta for use on 230 volt supplies. They are connected in star for 400 volt supplies. The winding numbers are;
A phase winding, L1-4,
B phase winding, L2-5,
C phase winding, L3-6.
For a star connection, #4,#5, and #6 are connected together and insulated. The motor is now suitable for 400V, 50 Hz use. 400V/50Hz x 60Hz=480V @ 60Hz.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[davidbeach]

What Bill said.

 

[waross]

Thanks David. eeprom has been around long enough and has enough smarts that I thought that possibly I was missing something.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[eeprom]

Thanks. Now I see...

 

[Amotor]

2 Black and 1 Red.

Is it possible there are some Hall sensors or something installed? What manufacturer? For the time being I would isolate these three wires and operate in Wye as the gentelman said.

 

[waross]

I am using a vfd

If you want to "juice" it up, you can use the delta connection and set the V/H to 230V/50Hz or 4.6/1.
Then at 480 volts you will have about 104 Hz and about 208% of rated speed and HP.


Bill
--------------------
"Why not the best?"
Jimmy Carter