GUIDE
What are common faults in inverters?
How to differentiate between major and minor faults?
Let's look at the causes of inverter failures and 32 correction methods.
1. How to distinguish between major failure and minor failure?
In case of a slight fault, the system will emit an alarm signal and the fault indicator will flash.
In the event of a significant fault, the system will issue a fault indication and the fault indicator will remain lit.
Simultaneously, a command will be issued to disconnect the high voltage and prevent it from being reconnected. The fault information and high voltage disconnect command will be recorded for future reference.
The major fault condition will not be cleared and the fault indication and high voltage disconnect command will remain in effect.
2. What are the small flaws?
Minor faults include: transformer overheat alarm, cabinet overheat alarm, cabinet door opening, unit bypass. The system does not store records of minor faults, it only displays the fault indication. The alarm will be automatically cleared once the fault has been resolved.
If a soft fault alarm occurs during inverter operation, the system will not shut down.
If a soft fault alarm occurs during shutdown, the inverter can still start normally.
3. What are the serious flaws?
When the following faults occur in the system, they are treated as major faults and the major fault type will be displayed in the upper left corner of the monitor.
These faults include external faults, transformer overheating, cabinet temperature overheating, drive faults, inverter overcurrent, high voltage power loss, interface board failure, controller communication failure, interface board communication failure , motor overload, parameter error and main control board failure. .
Drive failures include fuse failure, drive overheating, drive failure, fiber failure, and drive overvoltage.
For external faults, the high voltage interrupt state (cabinet door button or external contact) must be cleared before the system can be reset and returned to normal operation.
For serious faults other than external faults, a direct reset of the system can restore normal operation, but the root cause of the fault must be identified before powering up again.
Unit faults can only be detected when high voltage power is restored.
If the fault is difficult to diagnose and it is uncertain whether high secondary voltage can be applied, consult the manufacturer.
Note: Do not turn on the inverter twice without identifying the cause of the failure, as this may result in serious damage to the inverter.
4. The transformer over-temperature alarm is triggered when the temperature measured by the transformer thermostat exceeds the set alarm temperature (which is set to 100℃ by default). The thermostat then triggers an excessive temperature alarm, which results in the contact closing.
- Check whether the top or bottom fan of the transformer cabinet is working properly (if the bottom fan of the transformer cabinet is not working properly, there may be a large temperature difference between the three phases).
- Temperature resistance is measured correctly (no broken wires, poor contact with line plugs, if there is poor contact, the temperature value will be high).
- If the filter is clogged (take a sheet of A4 paper and place it over the filter to see if it can be absorbed, otherwise the filter needs to be cleaned).
- Whether the frequency inverter is operating under prolonged overload.
- If the ambient temperature is too high (ambient temperature must be below 45°C, otherwise better ventilation is required).
- Whether the fan switch and contactor mounted on the lower front of the transformer cabinet are disconnected.
- Is the transformer cabinet fan control and protection circuit in order?
5. When the temperature of the temperature measuring point of the over-temperature alarm unit cabinet is higher than 55℃, the system will send out the fault alarm.
- Check that the fan on top of the unit enclosure is working properly and that the fan switch installed in the secondary room has tripped;
- If the filter is clogged (take a sheet of A4 paper and place it over the filter to see if it can be absorbed, otherwise the filter needs to be cleaned).
- If the inverter operates permanently in an overload state.
- If the ambient temperature is too high (ambient temperature must be below 45°C, otherwise ventilation needs to be improved (wall fans or ducts on top of cabinets) or refrigeration equipment installed).
- Is the transformer cabinet fan control and protection circuit in order?
6. When the transformer overheats, the transformer temperature measuring temperature is higher than the set trip temperature (the default setting is 130℃), the temperature controller trip contact is closed, the system will report the serious failure of transformer overheating.
Check that the temperature displayed by the thermostat is above 130 degrees. If not, verify that the thermostat's overtemperature alarm value has been set to 130 degrees. For additional checks, see the section on transformer overtemperature alarm.
7. The cabinet temperature is too high.
When the measurement point temperature of the drive enclosure exceeds 60°C, the system will report a severe enclosure temperature overheat fault. For inspection items, see cabinet overtemperature alarm.
8. The cabinet door interlock alarm travel switch is compacted with the top of the cabinet door.
Verify that the travel switch “pre-travel” and “over-travel” settings are appropriate and that the electrical function of the travel switch is working properly. If not, replace the interface board.
9. Controller does not communicate.
Make sure the communications cable connecting the monitor control board to the main control board is connected correctly, and verify that the +15V and +5V readings on the monitor control board are accurate.
In case of problems, consider replacing the main control panel or monitor.
10. Main control board failure.
The monitor detects a fault on the main control board and reports it as such if it has established communication with the controller. To resolve the issue, replace the monitor or main control panel.
11. The interface board is not working.
The monitor does not establish communication with the interface board, which will reset every 5 seconds.
If the monitor, at 3 minutes and 30 seconds, does not establish communication, it will be considered a serious failure.
- Check whether the communication lines are normal and the terminals are correct.
- Whether the I/O board is working properly, especially the operating voltage.
- Is the external chip on the main I/O control board connected?
12. Parameter error.
If an incorrect parameter is set during parameter modification (this fault may occur during synchronous vector control), a parameter error fault will be reported. To resolve this, modify the parameters again and press the reset button.
13. External failure.
When the local high voltage disconnect button is pressed or the high voltage disconnect junction on the interface board is closed, the system will report an external fault. Check whether the high voltage disconnect button is pressed, the high voltage disconnect terminal is shorted, or the interface is defective.
14. Loss of high voltage power, the upper level of high voltage power disappears.
Typically caused by normal gate operation.
If there is an abnormally high voltage power failure (no fault recorded, no panel operation), check the upper distribution cabinet circuit open.
15. inverter over current.
When the inverter's output current exceeds 1.5 times its rated current, the inverter will activate its overcurrent protection. To troubleshoot issues, consider the following:
- Check that the output voltage board is working properly and for signs of short circuit or discharge.
- Check that the fiber is inserted securely and that the main circuit connections are tight.
- Confirm that the Hall component is receiving a normal power supply and that the output current signal of the Hall component is correct.
- Make sure that the parameter settings for acceleration time, torque rise, and starting frequency are not too short, too large, or too high, respectively.
- Check whether the motor or charging mechanism is blocked and whether the motor winding and output cable insulation are damaged.
- Ensure that all units are functioning properly by disconnecting the unit from the copper strip and using a multimeter or oscilloscope to check the unit's input and output voltages and waveforms.
- Check that the input power voltage is not too low.
- Consider whether there are power factor correction capacitors or surge absorbers on the output side of the inverter that could cause resonance with the conductor.
To eliminate overcurrent protection, check the relevant devices and eliminate possible causes of the problem:
- Check the unit's detection board for shorts and damage.
- Replace the controller signal board or main control board if necessary.
- Reduce the acceleration time and increase the current limiting factor if the problem is caused by the motor's low-speed current fluctuation.
- Replace the unit if the output voltage is low.
Note: In some cases, motor low-speed current fluctuation may cause repeated acceleration, deceleration and overcurrent protection due to the tooth groove effect. In such cases, reducing the acceleration time and increasing the current limiting factor can help the motor quickly pass through the floating area and avoid overcurrent protection.
16. Motor overcurrent.
The inverter output current is 1.2 times greater than the rated motor current and continues for more than 2 minutes.
Check that the parameter setting for the motor rated current is correct. Also, check whether the motor or load machinery is blocked and whether the power supply voltage is too low.
17. The motor does not rotate after the inverter is running.
Check inverter output for contactors or switch-type equipment. Make sure the inverter's primary output cable is connected to the motor. Observe the monitor for output current and voltage. If there is voltage but no current, it means the motor main circuit inverter is open. If there is voltage and current, check whether the cable has single-phase grounding or whether the motor rotor winding is open.
18. Major unit failure.
There are five types of drive failures, including fuse failure, drive failure, drive overheating, drive overvoltage, and optical fiber failure. The first three types of faults can be ignored if the unit has a bypass function and the bypass level is set to non-zero when valid.
19. When a fuse failure is detected, the fuse failure is reported.
Check if this is caused by a power outage; if the unit's three-phase input wires are loose; if the input fuse is intact. If the fuse is open, replace the unit.
20. Unit failure.
Check whether the unit's voltage detection board is short-circuited. If it is, drives A1, B1, and C1 will report a drive failure.
Check whether outputs L1 and L2 of the power unit are shorted. Otherwise, the unit's IGBT may be damaged. Replace the unit in this case.
Check that the motor insulation is in good condition.
Inspect the load for any mechanical faults.
21. Unit overheating.
There is a temperature switch (normally closed point) located on the radiator of the unit. If the temperature exceeds 85°C, the normally closed point of the temperature relay will be disconnected, causing the unit to report an overheat fault.
To troubleshoot the problem, check that the overhead fan is working properly, that the unit case fan switch has tripped, and that the filter screen is blocked (you can test this by placing a piece of A4 paper on the filter screen and checking if it may be adsorbed. Otherwise, you will need to clean the filter screen).
Consider whether the unit is operating in a long-term overload condition or whether the ambient temperature is too high (ambient temperature should be below 45°C. Otherwise, it may be necessary to improve ventilation with a wall-mounted fan, on the roof). air duct mounted or installing refrigeration equipment).
Check whether the unit control card is faulty and finally check whether the power unit temperature relay is working normally.
22. Unit overvoltage.
The DC bus voltage has exceeded the protection value, causing the inverter to issue an alarm for an overvoltage unit.
When the inverter is in operation, a low output voltage of a unit can lead to an imbalance in the three-phase output, resulting in a unit overvoltage alarm.
During commissioning of an unloaded motor, it is common for the DC bus to be overvoltaged and for the A1/B1/C1 units to report overvoltage. In this case, it may be appropriate to lower the reference voltage.
Check that the high voltage input power supply does not exceed the maximum allowable. If the supply voltage is very high, consider adjusting the transformer taps to 105%.
If overvoltage occurs during deceleration, consider increasing the inverter deceleration time setting to mitigate the problem.
23. Fiber failure
When the system cannot detect drive communication during startup, it reports an optical fiber failure.
Check that the power unit control power supply is operating normally (indicated by a green light). If not, replace the power supply unit. Also, make sure that the fiber optic connector between the power supply unit and the controller is not disconnected, and check whether the fiber optic cable is broken.
24. Unit deviation
The unit is equipped with bypass hardware and the bypass level parameter setting is non-zero. If the unit experiences drive failure, fuse failure, or overheating, the unit will ignore these three faults.
If one unit fails, causing it to be bypassed, the other two units in the same position will also be bypassed.
Although the inverter can still start and operate during a unit bypass, the rated output voltage and capacity will be reduced due to the decreased number of units per phase in series.
It is important to immediately identify and correct the cause of a unit drift and replace the faulty unit. The remaining two skipped drives do not need to be replaced.
Regular cleaning of the unit's drive board and control board is important as dust buildup on these boards can cause false alarms.
25. Operating frequency is not consistent with the supplied frequency.
There are several reasons for the situation where the frequency inverter cannot stop at a numerical point. These reasons include the limitations imposed by the acceleration and deceleration time on the acceleration and deceleration process and the need for the output frequency to reach a specified frequency.
When the system voltage is too high, the drive may not be able to stop at a numerical point to avoid triggering the DC bus overvoltage protection for its own protection. In these cases, it is recommended to connect the transformer taps to 105%.
In addition, if the inverter output current exceeds the set current limit value, the inverter will automatically reduce the frequency to reduce the output current and prevent overcurrent protection from triggering. This can occur when the input voltage is too low or when there is a sudden increase in load, a transient power failure, a failure of a hall element, drive detection board or signal board, or when the drive needs to decelerate in obtain power from the engine to maintain control.
26. Monitor the black screen.
To resolve the issue, press the system reset button located on the cabinet door. Please note that resetting the system will not affect the normal operation of the inverter. If the problem persists, inspect the monitor's power terminal for disconnection, check whether the connection cable is loose, check whether the 5V and 15V power supply is operating normally, and look for any obvious damage to the monitor's wiring. . If interference is identified, replace the monitor.
27. Parameters cannot be changed.
When the parameter modification option is disabled in the function parameter, only the determined frequency or the given parameter can be modified, all other parameters are blocked.
It is not possible to change most parameters while the system is in operation.
28. The inverter will automatically restart after shutdown.
In remote control mode, start and stop functions can only be performed via the remote terminal. If the starting mode in the parameter setting is flush start (with start closed and stop disconnected), the inverter will stop immediately if the emergency stop signal is disconnected during operation or if it is stopped by other means.
However, when the emergency stop signal is closed again and the remote start level signal remains present, the inverter will automatically start running.
29. The inverter will trip when turned on.
When the inverter is turned on, the magnetic surge of the transformer and charging of the unit's capacitors can cause the instantaneous RMS current to reach 6 to 7 times the inverter's rated current for a duration of several tens of milliseconds.
If the inverter upper stage current protection setting value is set too low, it may trigger the upper stage switch fast break protection. To resolve this issue, the top-level switchgear fast outage protection setting must be adjusted.
30. Output frequency oscillates at low speed during startup.
Some low-speed motors experience significant fluctuations in current due to the slot effect, causing the drive to experience repeated acceleration, current limit deceleration, and other problems instead of normal acceleration.
To resolve this issue, you need to increase the current limit setting, reduce the startup time, and replace the unit if the output voltage is low.
31. The upper level distribution board is tripped when the automatic bypass cabinet is automatically bypassed.
Verify that the time delay absorption relay in the bypass cabinet is set between 1.5 seconds and 3 seconds. Make sure that the calibration value on the board is not too small (it should be more than five times the rated current of the motor). Set the frame fast break protection time to more than 0.1 seconds.
32. The external terminal has an induced AC voltage.
It may be due to a remote start/stop, high voltage interruption, or system reset signal line sensing voltage. It is recommended to connect the passive signal separately from the 220 Vac power supply, using a shielded wire grounded at both ends.
It may also be due to the induced voltage of the signal cable in the remote control box and the power cable being tied together. To solve this problem, it is recommended to rewire the signal in the remote control box, using a shielded wire for the signal without sharp edges and making sure that the shielded wire strip is not too long.
For the 4-20mA current signal, an AC induced voltage (below 10V) may be present, which can be connected between the current signal and ground with a 275V/0.33uf capacitor.
