How to quickly deal with inverter motor failure?
With the development of inverter, the application of inverter motor has gradually become popular, and the use of inverter speed control on some production machinery has become a symbol of the renewal of these machines. However, due to the complexity of the working system of the inverter motor, various problems will occur in the process of use. It is very important to understand its common faults and detection methods.
Why is it so important to measure motors and their variable frequency drives?
There are a large number of motor systems in a factory, and their safe operation is vital to normal factory production.
Electricity consumption of motor systems accounts for 60-70% of the total electricity consumption of a factory, and is one of the important sources of cost savings for factories.
Inverter motor systems are very complex, and if they fail, they will cause major losses to production and it is difficult to find the root cause with ordinary meters.
Next, let’s take a look at – “What are the frequent failure problems encountered during the use of inverter motors? What will be the consequences?”
Inverter motor ommon faults and their effects
Type I Fault: voltage imbalance
Voltage imbalance, in short, the three phases of the three-phase system phase-to-phase voltage amplitude is different. The voltage imbalance at the motor terminals can adversely affect motor operation and cause problems on the input side of the drive. A voltage imbalance can lead to voltage gaps and excessive current flow into one or more phases. A voltage imbalance can also trip the current overload fault protection on the motor drive.
Type II Fault: Current Imbalance
Current imbalance is used to check for differences between phase current levels in a three-phase system. Excessive current imbalance can indicate or cause problems with the drive rectifier, which can cause the motor to overheat, stop and then fail to start and become less efficient. Voltage imbalance can lead to current imbalance.
Type III Failure: Voltage/Current Distortion
Voltage or current distortion can affect the operation of other electrical devices on the same circuit, and other loads (such as motors and transformers) may overheat and have a shortened life.
Type IV Failure: Motor Driver DC Bus Failure
DC voltage levels are used to check the value and stability of the drive’s internal DC bus and the effects of braking or power feedback (if supported by the drive). The intermediate circuit of the motor drive may cause the drive to trip if the DC voltage is too low. Low voltage can be caused by low voltage from the input power supply or by input voltage distortion (flat top cause).
The AC voltage ripple function is used to detect rapid fluctuations and AC components on the DC bus. Slight ripple is visible, depending on the load. If the ripple peaks have different repetition levels, one of the rectifiers may be faulty. Ripple voltages above 40 V may be caused by a capacitor failure or the drive rating may be too low for the connected motor and load.
Type V Failure: Motor Bearing Flashover
For possible damage to the motor bearings, flashover between the shaft and the motor frame is also known as EDM. When the motor shaft voltage exceeds the insulation capacity of the bearing grease, flashover current occurs and causes pitting and groove marks in the bearing seat ring.