What is the reason why the overhead crane resistor burns off the motor

The overhead crane generally uses a three-phase winding motor, that is, an external resistance is added to the rotor, which has a large torque and a small current when starting.

There are several reasons for burnout1Overload operation, thermal relay mismatch or protection failure, does not play a protective role; 2.The quality of the motor itself, if the coil is burned out, the coil is rewound, and the air gap of the motor itself is not standardized; 3.

Frequent operation, without waiting for the motor to stop, directly start the motor, so frequent work, resulting in the motor insulation aging too fast, the motor burns out; 4.Check whether the protection circuit is normal; Whether the three-phase current of the motor running current is normal; Whether the three-phase contact of the air switch is normal, etc. (Not original...)

When the motor load is unchanged, the motor is running in phase loss, such as triangle wiring, the two windings are connected in series, the wiring voltage, and one winding is the rated line voltage. The overall electromagnetic torque decreases, and the current must increase to drive the rated load, and the winding connected to the rated voltage burns out due to overcurrent. For example, in the motor star connection method, one of its windings exits the output out of phase, and the other two windings maintain the rated load, which will also be burned out due to overcurrent.

When the motor starts the phase, it generally cannot be started due to insufficient torque, but if the starting time is longer, it will also burn out due to overcurrent. The installation of phase loss protection device can avoid the motor burning due to phase loss.

It must have been shorted during the maintenance of the overcurrent relay. In the event of a failure, the stator may have no voltage, the rotor is overcurrent and there is no protection, so the motor and resistance are burned, or the contactor contacts are sticky, and the maintenance is not in place.

The problem you said mainly depends on which motor you are talking about, whether it is a hook or a big car, basically there are the following reasons, such as playing the reverse car, and the brake is not opened, they give any reason to increase the motor current, just like when we go to school, the voltage does not change, the current increases, and the electrical resistance does not change, so the resistance is burned out and the resistance is opened, and the motor is not good; There is also a mismatch between the resistance and the motor, and the nut on the resistor is not tightened.

Is the motor rotor or stator broken? It is also possible that the rotor burns out and your resistance wiring breaks first, which eventually causes the motor rotor to burn out.

Hello, it is a pleasure to serve you. The resistance is broken and there are the following two phenomena, in electronic products, the current on the resistor instantly becomes larger, the resistance is burned out, the phenomenon is that the resistance body will be scorched and blackened, if the current is very large, the resistance will be burned directly, this can be seen by the naked eye, the second is that the current is not very large, but it is still burned out in the resistance liquid, and the resistance body can not be seen from the appearance of the abnormality, then this needs to be measured with a multimeter, maybe the resistance value is buried and increased, maybe it is an open circuit.

For the main hook resistance box, it is generally the virtual connection of the resistance box, which leads to the oxidation of the terminal for a long time, and when the motor frequently starts and stops the forward and reverse rotation of the heavy load, it will cause the resistance box to heat up and smoke, thereby burning the wire of the resistance box.

Under normal circumstances, the resistance box heats up, and the temperature is normal as long as it does not exceed 300 degrees.