Life Span of Contactors

As far as I know there is no set time to replace a contactor in any application, but a general guideline could be the number of starts and stops every day....the more, the shorter the lifespan...but I feel if you got 10 years out of it, you got your money's worth....

This is why you have preventive maintenance to check and test components for wear and tear, and replace when needed...

There are too many variables to consider, I've seen it all, ants, lightning damage, frogs lizards snakes, failure of the other components, short cycling, water damage, loose electrical connections, defective parts, random failures...

I generally when I want a contactor to last as long as possible employ an oversized contactor, and spray WD 40 around the exterior, regularly...

If you have someone who can check it everyday with just a IR thermometer to look for hot spots, that's a good preventative measure...If a failure is imminent, there is generally an abnormal hot spot, if it is checked frequently the guy checking knows the normal temperatures and can spot a problem immediately....

http://www.naicranes.com/engineering/technical_reports/contactors.pdf

IEEE has standards that relate to system reliability, such as this “

IEEE Guide for Electric Power Distribution Reliability Indices, which has data that I have used to evaluate the benefits of using various technologies to construct a solution for various clients.

Manufacturers also have data on their own equipment that give you statistical data upon which you may decide to take preemptive measures. It also may be possible using high speed & sensitive data collection and analysis tools to detect imminent failure of a contactor, such as coil amperage, timing of armature action, high speed load current and voltage analysis at contactor opening and closing times, to detect imminent failure due to pitting, load spring weakening, armature jamming or wedging, lamination failure, pole cross-talk, earth leakage resistance, or some other anomalous behavior that could indicate a future failure.

In a previous life, the contactors had their top shell removed every 6 months to check for contact erosion and at the same time the shading rings were checked for security, insulation and not broken or cracked and excessive discolouration of the coil. The mechanical parts of the contactor were also checked

This was on contactors where the plant ran 24 x x7 for 363 days as year with a planned shutdown of a portion of the plant for a few hours every week to check some part of the plant.

A mean time between failure was logged to see if the maintenance was fit for purpose and not too short a time frame or excessively long. Doing thermal scans while running was discouraged because of the injuries that would occur if a contactor failed and flashed over as had happened.

I remember seeing a GE size1 contactor that controlled a clip motor that cycled from forward to reverse every second. 7 days a week,24/7 It was replace every year,with no contactor failures between changes.When I removed and inspected it,the anvil was hammered and slightly mushroomed,but the shading coil was unbroken,and it just kept on working.

The failures were mainly with the motor,and the repetitive F/R cycling.I recommended a pneumatic actuator instead of the motor.A/C pneumatic solenoids also have a shading coil that can be broken and deformed by millions of cycles,so I suggested a DC solenoid,which has no shading coil.A small dc power supply was required,and I deliberately oversized it by a factor of 2 to ensure long life.

The input to the power supply was protected by MOV's and properly sized fuses.

This was in the 1970's

I met a retired maintenance employee from the plant many years later,and asked about the clip controls and he said it was still working with the original parts 15 years later.

This was a critical step in the process,and if it failed,the whole section had to stop,and the result was a fault in the final product and production quantity.

I designed it to last,not to be replaced by minimalist engineering.