Common faults and treatment methods of frequency converter

2021-11-01 08:31:52 jact_elec

Common faults and treatment methods of frequency converter

JACT is based on AC inverter automatic control technology. We not only continue to provide customers with practical products and convenient services, but also tailor-made products and comprehensive solutions for specific industries.

The following are some solutions to common inverter failures:

(1) Short circuit protection

If short-circuit protection occurs during the operation of the inverter, it means that there is a short-circuit factor inside or outside the inverter. In this case, if the load is thrown away, that is, the inverter is disconnected from the load, and the inverter is switched on, the inverter should work normally.

At this time, we use a megohmmeter (or shake meter) to measure the insulation of the motor. The motor windings will be short-circuited to the ground, or the insulation of the motor wire and the terminal board will deteriorate. At this time, the motor and ancillary facilities should be checked.


(2) Overcurrent protection

Inverter over-current protection is generally caused by excessive load, that is, when the load current exceeds 1.5 times the rated current, it will be protected by failure and shutdown. This is generally not harmful to the inverter, but long-term overload is likely to cause the internal temperature of the inverter to rise, the aging of components or other corresponding faults.

This protection is also caused by the internal fault of the inverter. If the load is normal, the inverter still has over-current protection, which is generally caused by the detection circuit, which is similar to the elimination of short-circuit faults, such as current sensors, sampling resistors or detection circuits.

This protection is also caused by the internal fault of the inverter. If the load is normal, the inverter still has over-current protection, which is generally caused by the detection circuit, which is similar to the elimination of short-circuit faults, such as current sensors, sampling resistors or detection circuits.

(3) Over and under voltage protection

The over-voltage and under-voltage protection of the inverter is mostly caused by the fluctuation of the power grid. In the power supply circuit of the inverter, if there is a direct start or stop of a large-load motor, the momentary large-scale fluctuation of the power grid will cause the inverter to overshoot. , Undervoltage protection, but can't work normally. This situation generally does not last long, and normal operation can be performed after the fluctuation of the power grid. The improvement of this situation can only be avoided by increasing the capacity of the power supply transformer and improving the quality of the power grid. 

When the power grid works normally, that is, within the allowable fluctuation range (380V±20%), if the inverter still has this kind of protection, it means that the internal detection circuit of the inverter has failed.

(4) Over-temperature protection

The over-temperature protection of the inverter is generally caused by the high temperature of the working environment of the inverter. At this time, the working environment should be improved and the surrounding air flow should be increased to make it work within the specified temperature range. 

Another reason is that the frequency converter itself is not well ventilated in the cooling air duct. Some working conditions are bad, with too much dust and dust, causing the cooling air duct to be blocked and the fan cannot draw in cold air.

Therefore, the user should frequently clean the inside of the frequency converter. (Generally once a week). Some fans are damaged during operation due to poor quality, and the fans should be replaced at this time. 


Another situation is that in high-power inverters (especially multi-unit or medium-high voltage inverters), the temperature sensor is too long, close to the main circuit or places with strong electromagnetic induction, causing interference. Anti-interference measures. Such as using relay isolation, or adding filter capacitors.

(5) Electromagnetic interference is too strong

In this case, the inverter will not display the fault code after stopping, only the decimal point will be lit. This is a more difficult fault. Including display errors after stopping, such as random display, or sudden crash during operation, normal frequency display but no output, all caused by too strong electromagnetic interference inside and outside the inverter. 

In addition to external factors, the troubleshooting of this kind of fault is to keep the frequency converter away from the interference source with strong radiation. Especially for the main control board, in addition to taking necessary shielding measures, it is particularly important to adopt a method of isolation from the outside world. 

First, try to isolate the interface between the main control board and the outside world.

We use optical fiber transmission isolation in high and medium voltage and low voltage high power inverters and hoist inverters, and use photoelectric isolation in external sampling circuits (including short circuit protection, over current protection, temperature rise protection, and over and under voltage protection).

PLC isolation is used in the interface circuit between the hoist and the outside world. These measures have effectively avoided the electromagnetic interference from the outside world, and have achieved good results in practical applications.