Splint, There is also another source of voltage spikes that I have seen cause problems if not taken care of, that is back emf suppression of relays,solenoids, contactors etc, even if optoisolators are used for switching.
For AC devices a resistor/capacitor in series combination is used across the coil, the values depend on the size of the device, also on AC a varistor (voltage dependant resistor) can be used. On DC a diode should be wired across the coil in reverse bias to the DC supply i.e. anode to DC+. The diode will delay the opening slightly of the relay, but this is not usually a problem.
Al
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CNC, Mechatronics Integration and Machine Design.
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E. |