21 problems that should be noted when using the inverter (II)

11. For the case where the inverter drives the ordinary motor for constant torque operation, long-term low-speed operation should be avoided as much as possible. Otherwise, the heat dissipation effect of the motor becomes worse and the heat is severe. If you need to run at low speed and constant torque for a long time, you must use a variable frequency motor.

12. For occasions of lifting load and frequent start and stop, there will be torque generation. It is necessary to select the appropriate braking resistor. Otherwise, the inverter will often trip due to overcurrent or overvoltage fault.

13. When the motor has another brake, the inverter should work in the free stop mode, and the braking action signal will be issued after the inverter issues a stop command.

14. The blocking of the external braking resistor of the inverter should not be less than the requirement of the braking resistor allowed by the inverter. Under the premise of meeting the braking requirements, the braking resistor should be larger. Do not short-circuit the terminals that should be connected to the braking resistor. Otherwise, a short-circuit accident will occur through the switching tube during braking.

15. When the inverter is connected to the motor, it is not allowed to use the megohmmeter to measure the insulation resistance of the motor. Otherwise, the high voltage output of the megohmmeter will damage the inverter.

16. Correctly handle the problem of speed increase and deceleration. The acceleration and deceleration time set by the inverter is too short, and it is easy to be affected by “electric shock” and may damage the inverter. Therefore, when using the inverter, the acceleration and deceleration time should be extended as much as possible under the premise of the load device.

1. If the load is heavy, increase the acceleration and deceleration time; otherwise, increase the acceleration and deceleration time.

2. If the load equipment needs to be added or decelerated in a short time, it must be considered to increase the capacity of the inverter to avoid too much current and exceed the rated current of the inverter.

3. If the load equipment requires a short acceleration and deceleration time (such as within 1S), then the brake system should be considered on the inverter. Generally, larger inverters are equipped with a brake system.

17. Avoid the mechanical resonance point of the load device. Because the motor is in a certain frequency range, it may encounter the mechanical resonance point of the device, causing mechanical resonance and affecting the operation of the system. To do this, you need to set the skip frequency (or avoidance frequency) to the inverter and skip the frequency (avoid it) to avoid the resonance point.

18. Before the motor is used for the first time or after being placed for a long time before being connected to the inverter, the insulation resistance measurement must be performed on the motor (using a 500V or 1000V megohmmeter, the measured value should be no less than 5M ohm). If the insulation resistance is too low, the inverter will be damaged.

19. The inverter should be installed vertically, leaving room for ventilation, and the ambient temperature should not exceed 40 °C.

20. Anti-interference measures must be taken to prevent the inverter from being disturbed and affecting its normal operation, or the higher harmonics generated by the inverter interfere with the normal operation of other electronic equipment.

21. Pay attention to the thermal protection of the motor. If the motor is adapted to the drive capacity, the thermal protection inside the drive can effectively protect the motor. If the capacity of the two does not match, the protection value must be adjusted or other protective measures should be taken to ensure the safe operation of the motor.

The electronic thermal protection value of the inverter (motor overload detection) can be set within the range of 25%-105% of the rated current of the inverter.