I'm planning to use the following normally on push-button switch: http://uk.rs-online.com/web/p/push-button-switches/1336473/ According to the following data-sheet: http://uk.rs-online.com/webdocs/137f/0900766b8137f3b1.pdf it says:
Contact Current Rating: 650 mA @ 30 V dc
But in my application the button will be pushed less than a second where the voltage across it will be 48V and the current through it will be 48mA for less than a second.
Should I look at the power (P = I*V = 30*0.65) in this case, or I shouldn't use it since it says 30V in its ratings?
Push-button controls 48V supply and is normally open. Here is the part of the circuit where the switch is in LTspice(I didn't check this in scope):
Points A and B represents the terminals of the push-button. Below green plot is the potential difference across the switch terminals A and B:
And the blue plot below is the current through the switch:
And finally, I zoom to see both the voltage across the switch and the current through the switch:
What I understand from the above plots, the switch is exposed to 48V whenever it remains open. The moment the switch is closed, the potential difference drops quickly in nano-seconds to zero volts and micro-ampere level current passes through it.
What I understand from the first answeers is that, the problem with the following push button: http://uk.rs-online.com/webdocs/137f/0900766b8137f3b1.pdf is that if I use them in my circuit, they will be exposed to 48V all the time when the switch is normally open. So the real problem does not occur the moment I push the button but it occurs when the push button is not pushed at all.
Is that correct?