Cartridge heater earth leakage at elevated temperature
Cartridge heater earth leakage at elevated temperature
(OP)
I am doing some R&D work by heating steel to 800C using high temperature cartridge heaters. I am getting some earth leakage around 3mA at 230V AC at high temperatures causing RCD to trip out.
I am in discussion with cartridge heater manufacturer to improve performance of their heaters.
Would there be any safe way of stopping the tripping short of de-rating RCD to higher leakage current.
Measured leakage rises sharply around working temperature and falls when temperature is lowered. I assume insulation in heater is not up to the job.
Thanks
I am in discussion with cartridge heater manufacturer to improve performance of their heaters.
Would there be any safe way of stopping the tripping short of de-rating RCD to higher leakage current.
Measured leakage rises sharply around working temperature and falls when temperature is lowered. I assume insulation in heater is not up to the job.
Thanks





RE: Cartridge heater earth leakage at elevated temperature
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Cartridge heater earth leakage at elevated temperature
Where's this 3mA you're measuring?
T'wer me I'd try to confirm this hypothesis as then you could come up with an appropriate solution.
Possibly run the heater with DC or use an isolation transformer. Or assess the situation and use an RCD with a higher setting or dump the RDC altogether.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Cartridge heater earth leakage at elevated temperature
Typical of MgO insulation.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Cartridge heater earth leakage at elevated temperature
at 20 ma].I think you have to check the RCD device. High sensivity RCD [in Europe, at least], is rated for 6,10 and 30 ma. There are RCD devices with variable sensitivity also.