When Yaskawa inverter has a low voltage (UV) fault in the main loop, the following steps can be taken:
1. Preliminary inspection and /confirm/iation
View the fault code:
First, look at the fault code displayed on the inverter display to confirm whether it is a UV or related low voltage fault.
Check the input power supply:
Check whether the input voltage of the inverter is stable and meets the working requirements of the inverter.
Check whether the input power supply is out of phase, and whether the power cable is firm and has no broken wires.
2. In-depth investigation and testing
Check the rectifier loop:
If the input power is normal, then check the rectification circuit for problems.
Check whether components such as rectifier diodes and filter capacitors are damaged or aged.
Detect DC bus voltage:
For 200V class machines, UV alarms may appear when the DC bus voltage is below 190VDC.
For 400V class machines, when the DC voltage is lower than 380VDC, the fault alarm may appear.
Use a voltmeter to check the DC bus voltage to see if it is below the standard value.
Check the voltage detection circuit:
If the DC bus voltage is normal, but the inverter still reports a UV fault, it may be a fault in the voltage detection circuit.
Check voltage sensors, voltage amplifiers, undervoltage protectors and other components for damage or abnormality.
3. Troubleshoot and repair the fault
Improve the supply voltage:
If the power supply voltage is unstable or insufficient, take measures to improve the power supply voltage, such as adding a voltage regulator and adjusting the power line.
Replacement of damaged components:
If the components in the rectifier circuit and voltage detection circuit are found to be damaged, replace the new components in time.
Check and replace capacitors:
Use the U4-05 (Capacitor Maintenance) function to confirm the maintenance period of the capacitor, and if the value of U4-05 exceeds 90%, replace the motherboard or inverter.
Confirm the ambient temperature:
Check whether the ambient temperature of the inverter is too high. If it is too high, take measures to reduce the ambient temperature, such as adding heat dissipation devices and improving ventilation conditions.
Check for other relevant factors:
Check whether an alarm occurs when wiring circuit breakers, leakage circuit breakers (with overcurrent protection) or electromagnetic contactors are opened.
Check whether the capacity of the power transformer is sufficient. If not, replace the transformer with an appropriate capacity.
4. Preventive measures and daily maintenance
Regular maintenance:
Regular maintenance of the frequency converter, including cleaning, checking components, testing performance, etc.
Pay attention to the use environment:
Ensure that the frequency converter is installed in a well-ventilated and suitable temperature environment.
Avoid overload operation:
Avoid the frequency converter overload operation for a long time to reduce the possibility of failure.
Stop in time for inspection:
When the inverter fault alarm, stop the inspection in time to avoid the expansion of the fault or damage to other parts.