Unusual nameplate û 60C rise.

[electricpete]

I have a Reliance motor 1970’s vintage 800HP 4KV.

The nameplate includes:
HP – “800”
RPM – “890”
Ins Class – “F”
Ins Type – “RPI”
Ambient – “40” C
Duty - “Cont”
“Max Rise WDG 60C”

The items in double-quotes are the items which are custom-stamped into the nameplate. For example HP is printed onto the nameplate for general use and “800” is stamped as a parameter unique to this motor.

If I saw Max Rise of 80C, I would conclude this is a motor specified to have class F insulation and design for a class B rise (40C ambient + 80C average rise + 10C hot-spot allowance). I don’t know how to interpret the “Max Rise WDG 60C”Max Rise 60C. I am sure this is something we would not have specified during purchase of the motor.

My question: What do you think is the meaning of “Max Rise WDG 60C”Max Rise 60C

If I were attempting to predict aging/reliability based upon actual loading and measured winding temperatures in-service, do I need to give any consideration to this statement “Max Rise WDG 60C”Max Rise 60C or can I simply consider it to be class F?

(I am not interested in any general/philocophical discussion of aging evaluation, only the role of this 60C rise should play in an evaluation)

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[jbartos]

Suggestions:
1. If there happen to be a motor serial number or similar information on the nameplate, the motor nameplate data might be traced for a typo.
2. The motor manufacturer does not necessarily have to adhere to the NEMA Standards with every product.
3. The type of motor insulation should be used to establish the correct motor temperature ratings.

 

[electricpete]

Thanks jbartos

I agree with #3. That is the way I am planning to approach the problem unless I find any more info.

I would still like to understand the significance of the 60C.

Motor mfr is not available.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[jbartos]

Suggestion: Clearly, Class A temp rise 60degC pertains to the motor cost via the adder of 25%.
Visit

http://www.usmotors.com/PB210/2001/18_AccMod_S-T.pdf

for:
449 5000 5800 6800 8000 9600
25 % 25 % 25 % 25 % 25 % 25 %
Frame:
Adder:
Class "A" Rise
* Adder is percent of Base List Price.
* Make this adder for Class "A" Rise at 1.0 Service Factor (Full Load). This
includes the following options:
- "A" Rise At 1.0 Service Factor (By Resistance)
- 60C, 65C, 70C or 75C Rise At 1.0 Service Factor (By Resistance)
* Caution: Temperature Rise Below Normal may require a larger frame size.
Confirm frame size prior to quoting.

 

[aolalde]

“Max Rise WDG 60C” means; that motor will rise the winding temperature 60°C when it is loaded to nameplate load BHP.

If the insulation class is F (155 °C), assuming ambient temperature of 40°C the winding temperature will be 100°C.

The remaining 55°C will allow an increase of life expectancy for the insulation. Life expectancy doubles for each 10°C reduction from the limit temperature for a given insulation class.

That means you have a “very cool motor”.

 

[edison123]

Looks like a conservatively (or is it liberally ?? I never could get the nuance between the two right) designed motor. As Aolalde syas, you indeed have a "cool motor".

 

[gordonl]

Electricpete,

In your previous posting you said "motor mfr is not available", but reliance lives on under the Rockwell umbrella.

Reliance Electric Motors
6040 Ponders Court
Greenville, SC 29615
General information 864-297-4800
FAX 864-281-2433

http://www.reliance.com/docs_onl/online_motor.htm

 

[electricpete]

Thanks. jbartos, edison, aolalde - you have all suggested this is roughly equivalent to standard class F insulation with class B rise but with class A rise instead.

That seems to be reasonable conclusion. However we did not specify class A rise. I don't know where the 60C came from.

Motor OEM tech support for old customers is non-existent.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[jbartos]

Comment: Probably, there was some extra money to prudently spend on such a good item as the electric motor.

 

[aolalde]

Epete:

Electric motor designs do not necessarily have to match an insulation class rise. Like 80°C Rise for class B, and so.

Certainly, manufacturers are trying to squeeze the last available grade allowed for the insulation, for competitive economical reasons.

You mentioned that the nameplate had:

{The nameplate includes:
HP – “800”
RPM – “890”
Ins Class – “F”
Ins Type – “RPI”
Ambient – “40” C
Duty - “Cont”
“Max Rise WDG 60C”}

Meanning that a motor could be tailored with non standard features, including the temperature rise. The main characteristics of a particular motor are stamped in the Nameplate.