Re: electric relay
Posted: Fri Sep 25, 2009 12:16 am
Karl,
I don't really know how to answer that, as in 30+ years in the field I've never seen one fail - and I've used a bunch of them in just this application of spike suppression in relay circuits. They are pretty darn reliable if properly specified in the first place. Any switching diode with a Peak Inverse Voltage rating of 600V or more, and a power rating of 1 watt or more, should be fairly bulletproof in this application. I'd worry more about the reliability of the connections than the diode itself.
Just guessing, but I suspect that if a diode does fail it would go to a resistance somewhere between open and closed circuit. In this application, if the resistance is high enough that the wattage rating is not exceeded (about 200 ohms in a 14V system for a 1 watt rating), you'd probably never notice unless you checked it. If the resistance is low enough to draw enough current to significantly exceed the wattage rating, the diode would eventually melt or burn up and cause an open circuit.
Miles
I don't really know how to answer that, as in 30+ years in the field I've never seen one fail - and I've used a bunch of them in just this application of spike suppression in relay circuits. They are pretty darn reliable if properly specified in the first place. Any switching diode with a Peak Inverse Voltage rating of 600V or more, and a power rating of 1 watt or more, should be fairly bulletproof in this application. I'd worry more about the reliability of the connections than the diode itself.
Just guessing, but I suspect that if a diode does fail it would go to a resistance somewhere between open and closed circuit. In this application, if the resistance is high enough that the wattage rating is not exceeded (about 200 ohms in a 14V system for a 1 watt rating), you'd probably never notice unless you checked it. If the resistance is low enough to draw enough current to significantly exceed the wattage rating, the diode would eventually melt or burn up and cause an open circuit.
Miles