switch ratings

[jimmy]

hi

i was wondering, if i wanted to put a switch on a power supply, and the power supply transformer was 275 volts 150mA and the switch was rated at 250V and 2A, would the switch err explode or something?

thanks
Jim

[cd]

You're fine.  Let me guess, the switch is probably also rated 125V 4A?  Unless you pulled more than 2A @ 275V you'd blow it up.  150mA is OK.

[jimmy]

thanks!!

cheers
Jim

[Paul Perry (Frostwave)]

i was wondering, if i wanted to put a switch on a power supply, and the power supply transformer was 275 volts 150mA and the switch was rated at 250V and 2A, would the switch err explode or something?Jim

It depends whether you are switching the mains input to the transformer, which is 230v AC in australia & therefore OK, or the output of the transformer whihc is 275v AC & exceeds the voltage rating (but, you would get away with it, mains switches have a large safety margin).

But if you are switchig DC, after the power supply, you might have trouble, because a switch designed for AC has less rugged construction of the contacts, because as you break the current on turn off, the momentary arc formed extinguishes itself on the zero voltage part of the AC cycle. But switching DC is more of a mess. So sometimes you see a switch with a much lower current rating for DC.

[jimmy]

nah its gonna be straight from the transformer before the rectifier bridge.

thanks
Jim