First, due to long-term overload or overheating, the aging of winding insulation accelerates, the thinnest defect of insulation carbonizes, resulting in inter-turn short-circuit, inter-phase short-circuit or ground short-circuit and other phenomena which cause some burning of windings.
(1) Avoid motor overload as far as possible.
(2) To ensure that the motor is clean and ventilated and heat dissipation is excellent.
(3) Avoid repeated motor start-ups and do dynamic balancing experiments on motor rotors when necessary.
II. Phase Lack Work
At this time, the noise of the motor is very big, and the heat is serious. This is also the killer of the three-phase asynchronous motor. It usually burns out after ten minutes'work. If all the power supply systems are out of phase, it is likely that many motors will be damaged. Phase absence is often a burning phenomenon in one phase or two phases. Single-phase work is caused by one-phase open circuit of motor power supply. The key elements of open circuit are often fuse burning, bad electromagnetic contactor, disconnected power supply wire, or bad wiring.
There are many methods and equipments for motor phase-breaking protection. Searching for a large number of them on the internet, Xuli Hydraulic Press introduces the commonly used protection methods as follows: selecting thermal relay with phase-breaking protection equipment for phase-breaking protection; anti-current relay for phase-breaking protection; zero-sequence voltage relay for phase-breaking protection; wire-breaking voltage relay for phase-breaking protection; using speed-saturated current transformer for protection and so on.
3. The insulation of motor windings is affected by mechanical vibration, which makes the windings appear bad phenomena such as inter-turn relaxation, insulation cracks, etc. The damage effect keeps piling up. Thermal expansion and cold contraction make the windings suffer friction, and then accelerate the aging of insulation. After all, it causes the earliest carbonized insulation damage until the burning of windings.
(1) Do everything possible to avoid repeated launches, especially high-voltage motors.
(2) Ensure that the vibration value of the driven equipment and motor is within the regulation range.
4. The improper sealing of the motor itself causes the insulation of the Rao unit to be eroded, the most serious part or the thinnest insulation defect to occur point to ground, the phenomenon of inter-phase short circuit or inter-turn short circuit, and then causes some burnout of the Rao unit.
Motor burns down motor burns down
(1) Eliminate the leakage of equipment as far as possible.
(2) When repairing, pay attention to the sealing of every part of the motor, such as applying a small amount of 704 sealant on each flange, applying grease on the bolts, and installing anti-splash boxes at junction boxes and other places when necessary. For example, when the motor leaks, the protective cover should be made in the locality where the liquid and dirt are easily invaded.
(3) To the motor working in this environment, we should shorten the period of minor repairs and medium repairs, and timely mid-repairs should be carried out in serious cases.
5. Because of bearing damage, shaft bending and other factors, the temperature of iron core rises sharply due to friction between stator and rotor. Incineration groove insulation and turn-to-turn insulation are destroyed to form winding turn-to-turn short circuit or "shoot off" from the surface. Serious cases will cause stator core groove inversion, dislocation, shaft wear, end cover scrap and so on.
When unloading bearings, the bearings should be heated to 80 ~100 C, such as bearing heater, transformer oil boiling, etc. Only in this way can the quality of bearing equipment be guaranteed.
(2) It is necessary to clean the bearing carefully before it is used. No impurities can be left in the bearing chamber. It is necessary to ensure the cleanliness when grease is added.
(3) Avoid unnecessary spindle machining and motor end cover nesting as far as possible.
(4) When assembling the motor, it is necessary to ensure that the stator and rotor centers are aligned and not misaligned.
_The motor shell is clean and endowed, ventilation is necessary to ensure, cooling equipment can not be scaled, and the blades should be adhered to.
Prevent the mixing of various lubricating greases.
_Before bearing of equipment, all the bearings should be inspected carefully.
_For motors that have not been used for a long time, it is necessary to carry out the necessary collapsing inspection and update the bearing grease before use.