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10kv motor winding insulation
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Five measures to avoid burning of three-phase asynchronous motor in Chongqing
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Chongqing electric machinery repair plant has encountered the burning of users' motors all year round, some due to mechanical problems, some due to thermal relay problems, and some due to lack of phase.
As the old saying goes, if a worker wants to do a good job, he must first sharpen his tools. So how to avoid the motor being burned? Here is a brief introduction to the methods to avoid motor burning:
1、 Keep the motor clean
During the operation of the motor, there shall be no dust, water stains and sundries within 3M around the air inlet, otherwise once sucked into the motor, it will form short-circuit medium or damage the conductor insulation layer, resulting in short circuit between boxes and burning the motor.
Therefore, to ensure the safe operation of the motor, it is necessary to keep the motor and its surrounding environment clean, so that the motor can maintain a safe and stable working state during long-term operation.
2、 Ensure that the motor often works under the rated current
The overload operation of the motor is mainly caused by too large driving load, low voltage, or the driven machinery is stuck. If overloaded for a long time, the motor will absorb a large amount of active power from the power grid, the current will increase rapidly, the temperature will soar, and it is easy to burn the motor.
Therefore, it is necessary to ensure that the motor often works under the rated current, and pay attention to the operation of the transmission device, the concentricity of the coupling and gear transmission.
3、 Pay attention to check the temperature of the motor (too high temperature is the main factor for motor burnout)
In summer, the ambient temperature is high, and the temperature of the motor is easy to be too high. Here's the key point
The staff shall regularly check the temperature of the bearing, stator, shell and other parts of the motor, especially for the motor without voltage, current and frequency monitoring and overload protection, pay more attention to monitoring the temperature rise. If the temperature rise is found to be too high, it shall be shut down immediately for inspection.
① There is a short circuit between motor winding turns, between phase windings, between winding and grounding resistance, resulting in the increase of current in the winding, resulting in a sharp increase in its temperature, resulting in excessive temperature.
② The insulation between motor core pieces is damaged, which increases the eddy current loss in the core, and the core heating increases sharply, resulting in excessive temperature.
③ When the three-phase motor works without phase, the current in the other two-phase windings will increase, resulting in too high winding temperature. When the starting winding of single-phase motor is broken, the temperature of the main winding will also be too high.
④ The long-term operation of the motor under overload will also cause excessive winding current, increase winding heating and cause excessive temperature.
⑤ If the motor is started too frequently, the current at startup is more than twice the normal working current, which will also increase the winding heating and cause the temperature to be too high.
⑥ The poor electrical contact of the motor increases the heating at the connecting parts, resulting in excessive temperature.
⑦ When the grid voltage is too high or too low, the current in the motor winding increases, resulting in heating and excessive temperature.
⑧ When the bearing of the rotating part is damaged or lack of oil, the friction of the rotating parts increases or the temperature is too high due to impact.
⑨ The temperature is too high due to the failure of motor cooling parts or the blockage of ventilation duct.
⑩ The ambient temperature of the motor is too high.
In addition, the rolling element, raceway surface and bearing clearance of the bearing need to be checked regularly. In case of any abnormality, the bearing must be replaced before operation.
4、 Observe the motor for vibration, noise and abnormal smell
If the motor vibrates, the load connected to it will increase to varying degrees, increase the motor load, and overload operation will burn the motor. Noise and peculiar smell are precursors of motor failure, which must be paid attention to at any time.
Therefore, during the operation of the motor, especially the motor of high-power maintenance network, it is necessary to check frequently to see whether the motor end cover, anchor bolt, bearing gland, etc. are loose. Once problems are found, they should be solved in time.
5、 Ensure that the starting equipment works normally
Generally speaking, the quality of starting equipment determines whether the motor can be started normally. According to past experience, most burned motors are caused by abnormal operation of the starting equipment, such as phase failure start of the starting equipment, arcing and ignition of contactor contacts, etc.
So how to maintain the startup equipment? It is mainly cleaning and fastening. For example, unclean contactor contacts will increase the contact resistance, cause the maintenance network to heat, burn the contacts, and then burn the motor. Therefore, always pay attention to the cleaning and fastening of the starting equipment. The electrical control cabinet shall be set in a dry, ventilated and easy to operate position, and dust shall be removed regularly.
If you do the above five moves correctly, you can basically avoid burning your motor!
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