Motor temp 1

[Feg]

I am looking for your opinion on the following, a SIEMENS motor driving a fan, 400Kw 4 pole 3,300V, Class F, with 3 x PT100,s in the windings.

U1 60 deg C
V1 99 deg C
W1 70 deg C

I don't yet have the currents per phase, but i am wondering why there is such a difference in temperature and do you think there is a problem on the way. We did have a motor guy on site that was good especially with high to medium voltage motors but with cut backs he has been laid off.

F.E.G

 

[edison123]

It doesn't compute. You could measure the resistances of the RTD's with a multimeter at the marshaling box to see if they are that different.

 

[7anoter4]

First of all check the currents. Second check the RTD as edison123 said. If nothing is suspect there, then check the RTD microprocessor. These are some guide lines given by US Motors

:
"Newer RTD micro processor control systems are very sensitive. If the RTD checks out, here are a couple of items you may want to check.
Inspect the wiring between the motor and the control panel. Is the RTD wiring running in the same conduit with other electrical wiring? Stray voltage from other sources can induce unwanted voltages into the detector circuit. You may need to use shielded wire for your detector circuit or put the detector wire in a separate cable run far enough away from any possible influence of other conductors. An unbalanced bridge circuit in the control can also give false readings."

 

[Skogsgurra]

Letting good electric guys go does have a downside. I think that this is a case to prove that.

Your company shall get someone with the proper education do the work. There are consultants out there. I am totally against this site replacing professionals.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jraef]

I think Gunnar makes a good point. This site is for TIPS from one professional to another in the same field. We are not a resource to make up for the lack of an on-site expert. There are a host of issues involved in what could be behind these readings, some of which could point to problems with serious consequences. Someone on-site would go through a process of elimination starting with the measurement method and components, but everything we could do here is going to be conjecture.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376