What problems will occur when Mining Electric Motor is damp?

1. Electrical performance
1. Reduced insulation resistance
Moisture will invade the insulation material of the motor, causing the insulation resistance to drop significantly. Insulation resistance is an important indicator for measuring the insulation performance of the motor. When the insulation resistance decreases, the motor is more likely to leak during operation. For example, under normal circumstances, the insulation resistance between phases and the insulation resistance to ground of the motor should be several megohms or even higher, but after being damp, it may drop to hundreds of kilohms or even lower, which increases the risk of electric shock to the operator.
Low insulation resistance may also cause short circuits between phases or to the ground of the motor. When the motor is running, the short circuit between phases will increase the current instantly, which may burn the windings of the motor; the short circuit to the ground will make the motor casing charged, causing safety accidents.
2. Increased risk of breakdown
As the degree of dampness increases, the withstand voltage of the motor insulation material will weaken. When the motor is running at rated voltage or higher, the insulation layer may not be able to withstand the voltage and break down. Once a breakdown occurs, the motor will not work properly and the repair cost is high. For example, in the high humidity environment of the mine shaft, if the Mining Electric Motor is exposed to moisture for a long time, the possibility of its insulation layer being broken down will be greatly increased.
2. Mechanical properties
1. Bearing corrosion and wear increase
Moisture will cause the grease of the motor bearing to deteriorate and lose its lubrication and anti-rust effect. Without good lubrication, the friction of the metal parts in the bearing will increase and the wear will increase. At the same time, the chemical components in the water may corrode the metal surface of the bearing, causing pitting, scratches and other damage to the bearing.
Damage to the bearing will affect the rotation flexibility of the motor, increase the running resistance of the motor, and reduce the efficiency of the motor. When the load remains unchanged, the motor needs to consume more electrical energy to overcome the increased resistance, and abnormal vibration and noise may occur.
2. Winding deformation and damage
During the operation of the motor, the damp winding will be affected by thermal expansion and contraction due to the presence of moisture. When the motor is started or running, heat is generated, and the water evaporates to form steam, which expands the volume of the winding; when the motor stops running and cools, the steam condenses into water, and the volume of the winding shrinks. This repeated expansion and contraction may cause the insulation layer of the winding to rupture, the winding to deform, and even short circuit.
In addition, if the motor is damp and runs under high load, the heat dissipation performance of the damp winding decreases and the temperature rises, which may further accelerate the damage of the winding.
3. Operation performance
1. Difficulty in starting
Dampness will affect the electromagnetic properties of the motor. For example, the reduction of insulation resistance will cause the leakage flux of the motor to increase, which will change the torque characteristics of the motor. At startup, the motor may not be able to generate enough starting torque to overcome the resistance of the load, resulting in difficulty in starting.
For some mining equipment that requires heavy-load starting, such as large scraper conveyors, damp motors may not start normally, affecting the normal production operations of the mine.
2. Reduced efficiency and increased energy consumption
Due to problems such as bearing wear and winding damage caused by moisture, the energy loss inside the motor increases. On the one hand, bearing wear increases the mechanical loss of the motor; on the other hand, winding damage increases the copper loss and iron loss of the motor.
The efficiency of the motor will decrease with the increase of energy loss, and more electricity will be consumed under the same output power demand. This not only increases the operating cost of the mine, but may also put greater pressure on the power supply system of the mine.
3. Unstable operation and frequent failures
Motors that have been affected by moisture are prone to unstable phenomena such as vibration and increased noise during operation. This is because problems such as bearing damage and winding deformation caused by moisture will destroy the mechanical and electromagnetic balance of the motor.
Over time, various problems caused by moisture will affect each other, causing the frequency of motor failures to increase. For example, initially it may only be a decrease in insulation resistance. As the operating time increases, it may develop into serious faults such as short circuits and bearing jams. Frequent failures will affect the continuity of mine production and increase maintenance costs and downtime.