Changing Voltage

[CharlesFaller]

Is it economically practical to change a voltage supply of a MCC from 480V to 600V?
Our generator supplies 600V. Basically, we just want to remove the transformer that we are using from the supply to the MCC. I'm having second thoughts about this because prices of 480V and 600V motor has a slightly big difference. And we have to replace all our 480V motors to be compatible with the supply. I think it will be a very big expense for our company.
Please help me on this. I need to defend this to my manager.
Thanks!

 

[rbulsara]

Wasn't this answered in your own thread237-280347?


Rafiq Bulsara

http://www.srengineersct.com

 

[waross]

Dejavue all over again??? Do you want to interfere with your managers right to do something stupid but possibly lucrative?
The last time I saw something like this done, every generator and every motor was the wrong voltage. Someone was getting a kickback on all the transformers. Consider whether you want to interfere.

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

 

[edison123]

Now tell us, why your manager wants to remove the existing 600/480 V step down set-up ?

And yes, the cost of replacing/rewinding all your 480 V motors to 600 V is an expensive proposition.

Muthu

http://www.edison.co.in

 

[jraef]

We I don't think we can answer you very effectively on the economics of this, we have no idea what you have. For example if you have 4 motors, then the cost of 4 new motors might be less than that of 1 large transformer. But if you have 400 motors, no way is that going to be less than the cost of the transformer.

As to the MCC, it looks OK on the surface; the current will be lower so all the starter ratings will be fine, i.e. less current. But scratch the surface and you start adding more expense. On large motors, you may have to change out the circuit breakers because they might be too large for the motor current now (probably won't be much of a problem with smaller motors). All of the heater elements will need to be changed, or at least adjusted, to match the new motor FLAs. All of the Control Power Transformers will need to be changed, along with any primary fusing. There might be more little gotchas like that.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[edison123]

Or it's simpler and cheaper to rewind that generator to 480 V.

Muthu

http://www.edison.co.in

 

[CharlesFaller]

I'm sorry guys, like what I said in my earlier post, I'm a newbie in this company and actually I 'm not even in the group that's in charge of this. My boss just surprised me in asking me about this. I don't know if he's just testing me or something but in any case, I want to give him an answer that's as excellent as possible. That's why I really want to be sure and I asked opinions of more experienced guys.
Thank you very much for the replies.