It would be nice if electrical contactors lasted forever, but they don't. Like other equipment, they have a life span that can be shortened by various conditions. In the case of a contactor, these conditions range from things that can be stopped, like vibrations, to things that can't be stopped, like the electrical arc that the contacts produce when they open and close. 

The Electric Arc Itself

Every time contacts open and close to produce a current, they create an electrical arc. The appearance of this arc is very common, but it also leaves behind slight damage every single time. Over time, the damage builds up to the point that the contactor fails. There's not much you can do other than keep an eye on the contactor, especially if it's used a lot and therefore produces a lot of arcs.

Contact Bounce

Contact bounce is a phenomenon in which the contacts that are closing, close very suddenly and essentially bounce back from each other. The bounce itself is not really a surprise because the contacts are closing very quickly, which adds some force to the closure. But that bounce produces a secondary electrical arc, so you get double the arc problems from that one set of contacts. That makes the contactor fail twice as fast as it would with only one electrical arc between contacts.

Constant Mechanical Vibration

If the contactor is connected to machinery that vibrates constantly (a fan or a motor), or even if the contactor is connected to machinery that's connected to machinery that vibrates, the contacts can shake loose because those vibrations can travel. Sometimes they can be fixed by just reconnecting them, but other times, they break outright. A replacement contactor, plus some vibration damping, is what you need in this case.

If you find that vibration has been a problem, check the surrounding connections as well, not just those to the contactor. You may find additional damage that needs to be repaired so that the new contactor functions well. Check bolts and screws, too, as that vibration can have subtle effects on everything it touches.

You can find replacement contactors from companies, like YuCo and ABB, and from a number of sellers and for a number of configurations. Just be sure that any external causes of shortened life spans, like those vibrations, are addressed soon so that they don't affect the replacement contactor.

Contact a local supplier to learn more about contactors, such as YuCo replacement ABB EH contactors.

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