Effect of voltage on resistance wire life expectancy?

[kyle pender]

I am using a 30kW air heater which is using resistance wire. I am not exactly sure what type of wire it is and hope this will not be an issue in answering this question.

The heater is rated at 380V and 45amps(max)...my supply is 415VAC (+ 6% and - 10%) and 45amps.

Any idea if this extra voltage will effect the life expectancy of the element?

Thanks

 

[Grinkle]

Probably bad - if the rating of 380 and the supply of 415 are apples-to-apples numbers. The power dissipated in the element is V^2/R, so the element will be hotter than the heater design anticipates. This is dangerous to do with a heater, imo.

If there is a fan in the heater, the fan motor is potentially going to react poorly to being over-voltaged.

 

[anorlunda]

http://www.frankshospitalworkshop.com/electronics/training_course/images/bulbs_life_expectancy1.jpg

Incandescent bulbs also heat wires, so this curve should be relevant. Pay attention to what @Grinkle said about safety, especially with so much power involved. you could burn the place down.

 

[kyle pender]

Would a step down transformer be an option?

 

[anorlunda]

A transformer would work, but it might be hard to find and expensive. If this is temporary and not permanent, Renting a 415v heater might be the cheapest solution.

 

[kyle pender]

Yeah, I just had a quick look and they are extremely expensive...more than the heater itself! I am having trouble sourcing an off-the-shelf air heater which can provide the output temperature I need (at least 750°C at an air flow rate of 40-55 SCFM).

 

[anorlunda]

How about an electrician to get you 380v service?