In addition, the power frequency does not conform to the rated value, the mechanical part is blocked, the magnetic gap is too large due to the uneven pole surface of the iron core, and the environmental factors such as abnormal ventilation, too wet and too high ambient temperature all cause such faults. Coil disconnection fault is often caused by overheating and burning of coil, or by damage caused by external force.
For different reasons, different countermeasures should be adopted. In case of abnormal coil failure, the coil of the same model can be replaced. If the iron core is free of dirt or uneven polar surface, the polar surface can be removed or replaced according to the situation. All rights reserved. Web Design by. No Comments 0 0 0. Page Contents 1 First, Installation Precautions 1.
Run-time maintenance 2. Inactive maintenance. Prior to installing, 1. During installation, 4. Second, the maintenance of AC contactor. Electrical failure — Three different electrical issues can cause contactor failure. The insulation between the coil wires can break down and cause a short. The coil can become grounded through another metal component when the wiring insulation deteriorates. The coil can also become stuck in an open position.
Furthermore, what does the contactor do in AC unit? A contactor is an electrical relay that controls the flow of electricity to components in the AC unit.
The contactor sends voltage to the condenser and outdoor fan motor. Voltage from the thermostat is sent to the contactor and is registered by the contactor's side terminals. The following causes are probable. If overvoltage is applied to the coil, the coil's insulating film will be destroyed, and short-circuiting will cause high temperature. The color of the coil will change, and the resin around the coil will melt.
A contactor is an electrically-controlled switch used for switching an electrical power circuit. A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit , such as a volt coil electromagnet controlling a volt motor switch. By far the most common cause of contactor coil failure is, surprisingly to many, undervoltage.
This because the coil is designed to withstand the inrush current for a limited time only. One common reason is when the coil supply is taken from the main supply where a high current is causing the voltage to drop.
Too high continuous control voltage could also cause the coil to melt. Wrong product selection is another cause of contactor failure.
Contactor should be selected according to the type of load. The standard utilization categories define the current values which the contactor must be able to make or break. These values depend on:.
This category applies to all types of a. Application examples: heating, distribution. This category applies to starting, plugging, and inching of slip ring motors. On closing, the contactor makes the starting current, which is about 2. On opening, it must break the starting current, at a voltage less than or equal to the mains supply voltage. This category applies to squirrel cage motors with breaking during normal running of the motor.
On closing, the contactor makes the starting current, which is about 5 to 7 times the rated current of the motor. Breaking is light. Application examples: all standard squirrel cage motors: lifts, escalators, conveyor belts, bucket elevators, compressors, pumps, mixers, air conditioning units, etc.
This category covers applications with plugging and inching of squirrel cage and slip ring motors. The contactor closes at a current peak which may be as high as 5 or 7 times the rated motor current. On opening, it breaks this same current at a voltage that is higher, the lower the motor speed. This voltage can be the same as the mains voltage. Breaking is severe. Application examples: printing machines, wire drawing machines, cranes and hoists, metallurgy industry.
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