isolation voltage testing

[max1980]

Hi,

I'm actually working on a boiler controller. Alimentation is 240VAC. I use an onboard power supply to get a low DC voltage to drive a microcontroller. This controller drive a relay to drive a heater.

My controller has to pass the CSA norm.

I've been told that the isolation voltage between AC and control DC has to be 1.5kV and I that I should test it. They talk about it in therad thread97524...

I don't understand what is the utility of this test except passing the CSA norm... Someone know?

Thanks !!

Max

 

[chuckey]

If overhead cables get hit by lightning, then excessive voltage can appear on the AC outlet. FWIW Once we borrowed an AC mains spike recorder, and we were getting 3 KV pulses every 10 seconds and an occasional 7KV spike.
Frank

 

[max1980]

I understand the AC input of my product can get 3kV pulses. Because of this, a good design practice is to respect correct isolation voltage. Maybe it's just as simple as that.

If anyone has some more info, don't hesitate to write it down.

Thx!!

 

[jiripolivka]

Many electric and electronic devices are HV tested and 3 kV is a typical voltage for it. Check the national standard.
The reason can be as written above, Ac transformer breakdown an long power outdoor lines can drive the peak voltage even higher. Many years ago studies have shown that the classical insulating materials like paper, bakelite etc. tend to heat up when wet, and to accelerate the tests 3 kV became a norm.