Wye Delta Starter

[deetz]

We purchased a Smeral Nut Former. It has a large motor on it that is started via an autotransformer type Wye/Delta starting operation, I think. See pics. I am looking at using a Soft/Start to start the motor instead. My reasoning behind this is it looks old and dangerous. Also I think there is a lot of stuff in the control cabinet I can eliminate, thereby making the troubleshooting easier because we don't have any schematics or manuals. We did have it running when it fist came in. Any thoughts guys as to running it via a Soft/ Start, or the whole thing in general?

 

[Skogsgurra]

Does the motor have slip rings? If it has, then what you see is not a Wye/Delta starter or an autotransformer starter.

The resistor looks more like a WRIM starting resistor than anything else. And it does not look very dangerous either. Someone has put new cables there, and they do not seem to be high-temperature cables. So it could be improved. Otherwise, I wouldn't care to put a soft start or a VFD on it.

An old motor does not have windings that have been designed to withstand the PWM waveforms (aka VFD hardened) and there's a risk that you will need to rewind the motor or change bearings soon after a VFD has been installed.

Talk to a good winder shop and let them "identify" what kind of motor it is before you do anything more.



Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[jraef]

First off, "autotransformer type Wye/Delta starting" are mutually exclusive terms; it is one or the other, not both.

So that said, that's definitely not part of an autotransformer starter and I think Gunnar is right, it looks more like it is part of a controller for a Wound Rotor Induction Motor (WRIM), which would have slip rings connecting the resistors to the rotor of the motor (that's why he asked). The devices in that cabinet look like resistors that are used to control torque and speed. If it is a WRIM, you CAN retrofit them with a VFD if you need the speed control, but Gunnar's points on the motor not being made for that are valid, so you would need to take extreme measures to protect it. it can be done however, I have done it numerous times successfully. It just is not something you do on the cheap.

It is also possible to use a soft starter on a WRIM if you do NOT need to change the speed, but there are steps you must take to engineer the soft starter into the system, usually involving testing how the controller works NOW with your load. But for you that means hooking up that controller now just to find out, only to rip and replace it later. Kind of a lot of effort.

The other remote possibility is that they used what is called a "Closed Transition Wye-Delta" starting scheme, and those resistors are being used in the transition stage (it's complicated to explain to someone who doesn't know what it is, so just go with it for the time being). But typically you would not need that many resistors. I only mention is because it appears as though MAYBE only a few of them are wired to anything, it's difficult to tell in that photo. That may indicate that someone recognized what a nice resistor package that is and re-purposed it for use with a closed transition W-D starter. The good news if that is the case however is that it becomes a VERY good candidate for replacing all that with a solid state soft starter.

Can you take a picture of the motor nameplate and/or the starter itself?




"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[waross]

If you number the grids #1 to #6, from left to right:
There appears to be jumpers across the top from #1 to #6, from #2 to #5 and from #3 to #4.
There appears to be a shorting bar across the bottom of #4, #5 and #6.
Typical for a WRIM.
Am I seeing this correctly?

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

 

[deetz]

Here you go guys. The motor label is a little vague. Yeah maybe we will just run it the way it is and see how it works in production. The cable that was different was a quick fix just to see if the machine would run. I am making a new copper connecting rod like the other ones in there. I am having trouble trying to get all the pics in the same post, so bare with me.

 

[deetz]

motor Label

 

[Skogsgurra]

Yes, slip-rings. Just fix the cables. That will work.

Monday shake?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.