I am planning to use a DC drived SPST reed relay. Below I include the spec for voltage, current and power ratings.
Contact Rating: 200W
Carry Current: 5A
Switching Current: 3A
Switching Voltage: 3500V
I want to use this relay for 2000V – 3 Amp power source switching. I know it makes 6000W which is out of spec for contact rating.
However, my question is if I turn off the power before switching off the relay and turn on the power after I switch on the the relay can I use this relay with this voltage and current?
This is the spec link of the relay I want to use (model 5503 more precisely). Here, another one similar to it.
Best Answer
Yes, you can do this. The important thing is that you aren't switching 6kW. When the relay switches the voltage is zero, so the wattage is zero. And when power is applied, the relay sees either 3 amps and zero volts, or 2000V and zero amps, all within spec.
However, you need to be very sure the relay doesn't switch under power! The first switch event under power may be the relay's last, and the 6kW will make a spectacular failure.
Edit: In response to comments, the relay's safe operating area looks like this:
The area is bounded by I=3A, V=3500V, and VI=200W.