Example of a standard feeler gauge
Before operating the contactor, a general inspection should be made. Manually check for freedom of movement and general cleanliness, but do not attempt to adjust or reset parts. Joslyn Clark contactors self-adjust throughout their life, eliminating the need to clean arc chutes or reset contacts, and saving cost and labor.
Unlike contactors, power devices such as isolators, fuses, and power stabs require preventative maintenance. Prudent engineers will implement preventative maintenance programs, including checking the vacuum contactor by either a high potential or resistance test.
Mechanically, the interrupter on Joslyn Clark contactors is very well protected. The risk of failure due to factors such as cracked seals or being hit by a wrench is virtually eliminated. The phase assembly has anti-torque and over-compression features that prevent possible damage to the flexible bellows at any time in the interrupter’s life.
The remaining electrical life can be checked by measuring overtravel. This can be done electrically or mechanically without dismantling or requiring special tools. Before doing so, you must isolate the power supply with a visible disconnect. The interrupters can be checked for dielectric strength using a high-potential test set. A micro-ohmmeter will also provide data on contact resistance.
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