Low-voltage electrical faults and maintenance methods - Mitsubishi

In the process of operation, low-voltage electrical appliances will present problems due to improper use or long-term operation of aging components, and there are many kinds of problems, and the common problems are analyzed and dealt with.

1. Contact problems and repairs

The contact is the primary component of the low-voltage switching coupon, and common problems are overheating, wear and fusion welding.

1. Contact overheating: Contact overheating refers to the cause of contact overheating or burns caused by the heat generation of the working contact exceeding the additional temperature and the treatment method

(I)) The contact pressure should be adjusted for overheating caused by the lack of contact pressure, usually to replace the tension spring pressure tissue. The measurement method is shown in Fig

(2) If the contact is poorly touched, the contact surface is oily or uneven, or the contact surface is oxidized, the contact can be cleaned up, and gasoline or knives can be used to remove it.

(3) If the operating frequency is too high or the operating current is too large, first check whether the power supply voltage is in the rated voltage scale and whether the load is overloaded, and then exchange the electrical appliances with larger capacity as needed. Electrical appliances with large capacity should be replaced or degraded due to ambient temperature or used in a closed environment.

2. Excessive wear of contacts, there are two types of contact wear damage, namely electric grinding and mechanical wear, which should be replaced when worn to a certain extent. Causes of excessive wear and tear and cleaning methods;

(1) Excessive wear caused by the non-synchronization of three-phase contacts can be adjusted to synchronize and replace the contacts.

(2) If it is formed by a short circuit on the load side, it is necessary to clean up the short circuit.

(3) If the overtravel is too small and the capacity is lacking from time to time when the equipment is selected, it should be replaced with a large capacity equipment.

3. Contact fusion welding Contact fusion welding refers to the phenomenon that the dynamic contact touch surface is welded together after melting. Causes of contact soldering and cleaning methods:

(1) If the operation frequency is too high or overloaded, the equipment should be selected from scratch according to the operating conditions.

(2) If the contact pressure is too small, the tension spring pressure should be adjusted or a new pressure tissue should be replaced.

(3) If there is a metal foreign matter on the surface of the contact, replace the contact with a new one.

(4) If the voltage of the operating circuit is too low or the contact is stuck in the direction of the just touch, the operating voltage should be improved to eliminate the jamming phenomenon.

Low-voltage electrical faults and maintenance methods - Mitsubishi

Low-voltage electrical faults and maintenance methods - Mitsubishi

2. Problems and repairs of electromagnetic structure

Electromagnetic structure is an important part of low-voltage electrical appliances, playing the role of energy conversion and operation movement, common problems are loud noise, can not be suction or lack of suction, do not release or slow release, coil overheating or burning, etc.

1. The causes and treatment methods of large noise;

(1)) If the power supply voltage is low, the power supply voltage should be improved.

(2) If the armature is in contact with the iron core and there is oil, dust or rust on the iron core, the touch surface should be cleaned up.

(3) If the touch surface of the iron core is caused by excessive wear and unevenness, the iron core should be replaced.

(4) If the parts are skewed or formed by mechanical jamming, the relevant parts should be adjusted or cleaned up from the beginning.

(5) If the contact pressure is too large, the contact tension spring pressure structure should be adjusted.

(6) If the short-circuit ring is damaged, replace the iron core or short-circuit ring.

2. After the armature cannot be sucked or the suction power is lacking, the reasons and treatment methods for the armature cannot be sucked or the suction power is lacking:

(1)) If the power supply voltage of the operation circuit is too low, or the wire is broken, the coil inlet and outlet lines fall and the wiring is faulty, the power supply voltage should be increased and the line should be cleaned up.

(2) If the power supply voltage is too low or shakes too much, or the movable part is jammed, the shaft is rusty, skewed, etc., the power supply voltage should be adjusted and the fault of the movable part should be removed.

(3) If the contact pressure is too large or the overtravel is too large, the pressure organization should be adjusted or replaced.

3. When the armature is not released or the release is slow, when the power supply is disconnected, the armature is not released or the armature is released slowly, and the reasons and treatment methods are presented:

(1) If the pressure of the contact tension spring is too small, the pressure organization should be adjusted or replaced.

(2) If the contact is formed by fusion welding, the cause of fusion welding should be found and the contact should be replaced.

(3) If the movable parts are jammed or the shaft is rusted or skewed, the relevant parts should be adjusted or the shaft should be replaced. If there is oil stain on the end face of the iron core or the air gap between the end faces disappears, the end face should be cleaned or the repair core should be replaced.

(5) If the reaction tension spring is damaged, the tension spring or the entire reaction force organization should be replaced.

4. Causes of overheating or burnout of the coil during the operation of the coil and the cleaning method of the fault:

(1) If the coil voltage is too high or too low, the power supply voltage or coil voltage should be adjusted.

(2) If the operating frequency is too high or the coil parameters do not meet the requirements, the coil needs to be replaced or the equipment should be selected according to the application conditions.

(3) If the end face of the iron core is uneven and there is a gap between the armature and the iron core, the iron core should be repaired or replaced. If the coil insulation aging is caused by an inter-turn short circuit or a partial short circuit to the ground, a new coil should be replaced.

There will be other faults in the electrical industry, and when the fault analysis and cleaning should be carried out according to the practical phenomenon as much as possible to analyze the causes, sweep them one by one, operate carefully in accordance with the safety requirements, and carry out the power transmission test operation after confirming the correct cleaning and wiring.

Low-voltage electrical faults and maintenance methods - Mitsubishi

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