Temperature Effect On NGR sizing

[ohms]

Apart from the standard NGR sizing calculation, do we need to take account the effeect of temperature on NGR sizing as well.

Thanks if someone can guide me to calculate this factor.

 

[dpc]

If you are talking about ambient temperature and a 10-second resistor rating, I'd say no.

What type of temperature are you concerned about?

 

[powerjunx]

ohms:

You may follow this link,

http://www.postglover.com/

They provide better literature to your query.






"Whenever you are asked if you can do a job, tell them, certainly I can! Then get busy and find out how to do it." Theodore Roosevelt.

 

[ohms]

Yes, ambient temperature.
I used the standard temperature coefficient to evaluate the inrease in resistance and therefore the current limit.
NGR is rated for 25C and ambient is 50C.

But the effect is negligible.

 

[cuky2000]

Grounding resistor are rate by IEEE std as follow:

1) Ambient temperature: < 40°C and the
2) average temperature: < 30°C for cooling air for any 24-hour period.

3) The altitude does not exceed 3300 ft (1000 m).

_{CLARIFICATION: For GND resistors rated for typical temperature rise of 375° ,610° or 760° C, a few degree above the rated ambient temperature may not have significant impact on the equipment performance. However, if the temperature is unusual high, this need to be checked}