Contactor / Motor Starter coil voltage question. 4

[itsmoked]

A super heavy grinding machine I'm looking at is to be supplied 220V 3ph (About 115A). Looking into one of its control bays I see every coil for every motor starter and relay are clearly labeled 110 or 120V 60Hz.

There is NO control transformer and all control power is derived from direct connections between the three phases.

How are these coils not toasting? What am I missing? Are the overloads somehow dropping 120V?

Here's the general look:

It's all Allen Bradly stuff from wayyYYYYYYY back.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Bill; I'm very sorry I botched the transformer number.. The V48M22T45EE is indeed the 480/240 model that David sharply suggested. My question pertaining to 208V was written correctly but a referred to the wrong model number.


I meant to post: V48M28T45EE.

It appears to me I could achieve up to 236V L-L using the 432V taps against my 490V. (Yes, I recognize the 498 could drop considerably during peak times.)

I have my mitts on a V48M28T45EE whereas all the V48M22T45EE are on the east coast.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

An industrial machine of that age probably ran happily for years on 208 Volts. As far as I know the 240 Volt open delta solution was mostly used for residential AC and single motor supply such as a farmers irrigation pump. By the 50s and 60s, utilities (in North America) had realized that a wye delta transformer bank was a really bad idea and stopped supplying 240 Volt delta.
That old motor may have been built to a +- 15% voltage tolerance.
You may consider adding a 480:120 Volt control transformer if you are going to boost the line to line voltage very much, but in the end the controls will probably survive a voltage a little higher than 120 Volts.
It sounds as if you are well on track with the available transformer.
Yours
Bill


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

 

[itsmoked]

Thanks Bill for the confirmation. I'll go with the "28" then.

I'll also be using a control transformer. I'll probably need a whopper looking at that big contactor. Once I get it all running I'll understand enough to update everything. I'll just stick with 120Vac coils everywhere so the control transformer will still apply.



Ever heard the saying, "A control transformer should be about the same volume as all the coils it will power at one time."?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[squeeky]

If you can’t find the exact transformer voltages look for one with the correct insulation and then the correct turns ratio. If not a more expensive option to run two transformers in series with the correct final output. Depends how desperate you are.

Now I climbed out of the box for this one. How well will your machine run on a non-sinusoidal wave? I have used VSDs (VFDs) in many non-standard applications. On a good quality unit you can lower the output voltage. If desperate, I would definitely try this one if you needed it to run.

Finally look at changing everything to your common voltage and control system. If you lose the transformer you are back at square 1.

 

[itsmoked]

Thanks squeeky. I've got a transformer that will do the trick nicely.

Here's the beast:

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Well that sucked big time. Picked up that 45kVA transformer installed it... It was defective.

BOOM!

And I do mean BOOM Inside the X3 coil. I'll never not megger a transformer ever again.

Keith Cress
kcress -

http://www.flaminsystems.com