As a technical support engineer, I get a lot of support enquiries requesting replacement relays. Most of these application problems could be avoided by using the correct type of relay.
Solenoids are a common method of controlling valves in an automated machine. They do not have a particularly high holding current, however they are often used in high frequency switching applications and it’s this factor which will cause any associated mechanical relay to eventually fail.
DC Solenoids are an inductive load, meaning there will be an initial inrush on start-up, which when using a mechanical relay causes an ARC between the cathode and the anode during the switch from off to on. It’s this arc which, over time, will damage the relay contacts and eventually lead to relay failure.
