Using Arduino relay board outside its intended voltage

arduinocoilhigh voltagerelay

I am making a multistage coilgun, with the switching of stages controlled by an Arduino Uno R3. There are ten stages total, and each stage has 5 80uf 330v photoflash capacitors. I need a way to switch that high voltage into the coils, and I have decided to use an Arduino to control that. The problem is, I don't have the money or time to use correctly rated relays, and wire them up to work with the Arduino. So I was looking at the relay boards sold for switching 120VAC, but the voltage I am switching is very far outside the rated voltage for the relays. Would it still work, at least in short term, or would it fry the relays instantly, or weld their contacts? any help is appreciated.

The relay board I am considering: http://www.ebay.com/itm/16-Channel-5V-Relay-Module-Optocoupler-Protection-Power-Supply-Arduino-PIC-DSP/252124532517?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D167e4df2b792461f8cfaff32c63a7e26%26pid%3D100338%26rk%3D1%26rkt%3D17%26sd%3D291440146340

Best Answer

Likely the contacts will weld the 1st time you use it.

2nd, the pull-in time of the relays will vary (nearly randomly), and this will degrade the sequencing of your coil gun.

3rd -- the EM pulse from the coil gun might cause the Arduino to malfunction. You'll have to shield it very well from the discharge -- the relays might not allow that.

Best to use semiconductors -- IGBTs would be well suited for this task, and can run 1000's of A