motor questions

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augie47

augie47

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I searched the forums but did not find answers to two questions that have arisen on a job abouth which I have limited knowledge.
The job has a 480v service. There are a number of smaller motors that are foreign, 6 lead with a terminal block with 3 leads marked delta, and three marked Y. (also jumpers supplied). What connections are made to operate these motors on a across-the-line magnetci stareter?

Secondly..One of the larger motors, still 480v, has 1000v "shielded cable"..3 phases, a set of shield wires and then an overall thin shield jacket. The starters are not at the job yet, but I assume this will be VFD..how are the shields terminated ?
(one end?) (shield wires and jacket ?)

Thanks
 
You have a wye start, delta run motor. Think of it as the three-phase equivalent of a single phase CSIR, but without the cap. To start this motor, you either need a special wye-delta starter, or your own contactors with a your own timing circuit.
 
motor

motor

marc, I have some experience with y/D motors and using them on Y/D staters. These are relative small motors, not requiring reduceded starting and the supplied starters are across the line. My menory is you can operate a Wye-Dlta on an across-the-line, I just don't recall the conmection.
 
I ran into some Siemens motors that had a delta-wye label and jumpers on the motor terminals. I found out that the jumpers were to be used in one configuration at 208 and the other at 480. These motors were 3,5,7.5 hp, no need for delta wye start. That may be what you have.

These motors were used on both across the line and VFD's on a piece of German equipment.

Hope this helps.
 
boater bill,
While I have seen that too, in reality, you can't make that voltage change with a only a delta/wye connection change. The change in the voltage is by a factor of the square root of 3 when you change from delta to wye. If the windings are rated at 277 volts and you connect them in a wye then you need to feed the legs of the wye with 480 for each winding to see 277. If the windings are rated 208, then the wye connected supply voltage should be 360.
Don
 
Marc,
If you're starting it across the line, you only use the delta run connection, and cap off the wye start leads.
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Are you sure? The only 6 lead motors that I have worked with, you always use all 6 leads. For a wye 3 of the leads are connected together and the other 3 are connected to the supply wires. For a delta two motor leads are connected to each supply wire.
Don
 
don_resqcapt19 said:
Marc,

Are you sure? The only 6 lead motors that I have worked with, you always use all 6 leads. For a wye 3 of the leads are connected together and the other 3 are connected to the supply wires. For a delta two motor leads are connected to each supply wire.
Don
Click to expand...
Yes, I'm sure. Follow my link in the earlier post.
 
Marc,
Yes, I'm sure. Follow my link in the earlier post.
Click to expand...
I did and I don't see anything that shows capping 3 of the 6 leads off. Look at the drawing at the bottom right of the second page. That is a 6 lead wye/delta setup.
Don
 
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