Test run of DC motor

After the inspection and treatment before the DC motor is put into operation, the commissioning can be carried out after the operating conditions have been met.

Commissioning of 1. generator

(1) Starting

1. Adjust the field rheostat to the breaking device.

2. The generator is temporarily unloaded and the prime mover drives the generator to the rated speed.

3. Adjust the magnetic field rheostat so that the voltage gradually rises to a certain value.

4. Close the load switch and gradually increase the load, or adjust the magnetic field rheostat to increase the load to the rated value.

5. Adjust the terminal voltage to the rated value.

(2) Parking

1. Gradually reduce the load on the generator while adjusting the field rheostat to the open position.

2. Cut off the load switch.

3. Stop the prime mover.

Test run of 2. motor

(1) There are 4 starting methods for starting DC motors: direct starting method, armature circuit series resistance starting method, decompression starting method and speed regulation method.

The direct starting method has a large starting current, and the maximum impact current can reach 15 to 20 times the rated value. Therefore, it has a large impact on the power grid and the motor itself. It is usually only used for starting current 6 to 8 times the rated current and power is not greater than 4kW. DC motor. The armature circuit series resistance starting method has a large energy consumption during the starting process and is not suitable for large and medium-sized motors that often start. Decompression starting method and speed regulation method, low energy consumption, smooth starting, used for all kinds of DC motors that need to be started frequently.

The starting steps are as follows:

1. Do not carry a load when starting the motor for the first time.

2. If it is a speed regulating motor, the main potentiometer (ie speed controller) should be adjusted to the lowest speed position.

3. Turn on the armature and excitation power of the motor, and adjust the master potentiometer to gradually increase the speed of the motor until the rated speed.

4. After the motor runs normally without load, take the load again and repeat the above procedure.

(2) Parking

1. If it is a speed regulating motor, the speed should be reduced to a minimum first.

2. If necessary, remove the load (except series motor).

3. Cut off the armature power supply, and then cut off the excitation power supply to restore the starting control device to its original state.

(3) Precautions The following matters should be paid attention to when the DC motor is in test run:

1. The idling time of the motor shall be not less than one hour. Because the brush can ensure good contact with the commutator through long-term grinding, which is of great benefit to the normal operation in the future.

2. During the trial operation period of more than one hour, observe whether the indications of the ammeter and voltmeter are normal, and check whether the motor has abnormal vibration, heat, oil leakage and noise. At the same time, under the rated speed of the motor, observe the spark under the brush.

3. After shutdown, the condition and heating of the stator, armature and bearing should be comprehensively checked.

4. For DC speed regulating motor, during the test run, the excitation voltage, armature voltage, current and rectifier bridge three-phase current should be closely monitored to observe whether there is oscillation, imbalance and other phenomena. If necessary, the waveform of armature voltage should be observed with an oscilloscope. If any abnormal phenomenon is found, the thyristor rectifier shall be adjusted before commissioning.