1. power supply causes overheating of the motor to produce fault:
(1). The power supply voltage is too high. When the power supply is too high, the anti electromotive force, magnetic flux and magnetic flux density of the motor vendors are all increased. As the size of the iron loss is proportional to the square of the flux density, the iron loss increases, causing the core to overheat. The increase of magnetic flux leads to a sharp increase of the excitation current component, resulting in the increase of 1 copper loss in the stator winding and the overheating of the winding. Therefore, when the voltage of the power supply exceeds the rated voltage of the motor, the motor will overheat.
The power supply voltage is too low. If the power supply voltage is too low, if the electromagnetic torque of the motor is kept constant, the flux will decrease, the rotor current will increase correspondingly, and the load current component in the stator current will increase, causing the copper loss of the winding to increase, resulting in the overheating of the stator winding and the rotor winding.
The power supply voltage is asymmetrical. When the power line phase breaker, fuse a fuse, or knife head start equipment burn causes a phase barrier, will cause the three-phase motor phase winding single-phase walk, which run through the high current and overheating and burning.
The three phase power supply is unbalanced. When the three-phase power is unbalanced, the three-phase current of the motor will be unbalanced and the winding overheating will be caused.
The 2. load causes the motor to overheat the reason that the motor overheating causes the following reasons:
1. Motor overload operation. When the equipment is not matched, the load power of the motor is greater than the rated power of the motor, then the motor's long term overload operation (i.e. the small horse drawn cart) will cause the motor to overheat. Maintenance of motor overheating, should first find out the load power and motor power are matched to the prevention to remove. The mechanical load of the drag is not normal. Although the equipment is matched with the metal element analyzer, the mechanical load of the dragging is not normal. The load is large and small at the time of operation, such as the overload of the motor and the heat when the feed quantity of the threshing machine is too large.
The machine that is dragged is malfunction. When the dragged machinery fails, the rotation is inflexible or jammed, the motor will be overloaded and the motor winding is overheated.
3. the motor itself caused overheating, the cause of overheating caused by the motor itself is the following:
1. The motor winding is broken. When there is a phase winding in the motor winding, or a branch circuit breaker in the parallel branch, it will cause the unbalanced three-phase current and make the motor overheated.
The motor winding is short circuited. When the motor winding is short circuited, the short-circuit current is much larger than the normal working current, which makes the copper loss of the winding increase, resulting in the winding overheating or even burning.
The motor is wrong. When the delta connected motor fault in a star, still with motor running at full load, the stator winding current flowing to exceed the rated current to the motor, and even self parking, if stopped for a long time and did not cut off the power supply, winding not only seriously overheating, also will be burned. When a star connected motor is wrongly connected to a triangle or several coil groups are connected into a branch, the motor is wrongly connected into two branches in parallel, which will make the winding and core overheated and burn the winding seriously.