Fault and maintenance of frequency converter

Faults and maintenance of frequency converter include: undervoltage fault, overcurrent fault, overload fault, overheating fault and switch power supply damage.

1, undervoltage fault

Under-voltage fault of inverter refers to the low voltage of main circuit, which may be caused by lack of phase of power supply, too many inverters working or starting at the same time, damage of current-limiting resistor or short-circuit current-limiting resistor of thyristor in DC circuit of inverter, interference from outside or between inverters, etc.

The solution is to check the input part of the inverter, check whether the power supply of the inverter is open, whether the contactor contacts are in good contact, whether the contact resistance is too high, and whether the output voltage of the transformer is normal. Try to reduce the number of inverters that start or work at the same time and enhance the anti-interference ability of the inverter.

2, over-current fault

Overcurrent fault is one of the common faults in inverter maintenance. The fault causes include too short startup acceleration time, sudden increase of load, short circuit of inverter output, uneven load distribution, damage of internal rectifier or inverter components, lack of phase of power supply, output disconnection, internal motor fault and grounding fault.

Maintenance methods include fault inspection, extending acceleration time, designing load distribution, checking lines, preventing interference and mechanical vibration, and reducing sudden load change.

Step 3: Too much

Overload is one of the common faults in frequency converter maintenance. Overload fault may be caused by motor overload or frequency converter itself overload. The frequency converter with poor overload ability is prone to overload alarm, while the frequency converter with strong motor overload ability generally does not appear.

Detecting the output voltage of the inverter can judge whether there is overload fault, and check whether the power supply voltage and the three-phase voltage on the motor side are balanced. An ammeter can be used to check the output current of the inverter and compare it with the running current value displayed on the display screen to determine whether there is a big error.

4, overheating fault

Overheating fault is a common problem in inverter maintenance, which may be caused by excessive ambient temperature, poor ventilation, blocked or damaged fans, and heavy load.

Solutions include checking the heat dissipation of the bottom plate, cleaning up the garbage in the air duct and keeping the ventilation smooth. Overheating fault may also be caused by transformer overheating. Solutions include reducing the temperature of the inverter, regularly overhauling the inverter, replacing the fan and reducing the load.

5. The inverter switching power supply is damaged.

The damage of switching power supply of frequency converter is a common fault, which is usually caused by the damage of components of switching power supply or the short circuit of load. Danfoss inverter adopts a new pulse width integrated controller uc2844 to adjust the output of switching power supply, and uc2844 also has current detection.

Voltage feedback and other functions. When there is no display, no voltage at the control terminal, and DC 12V and 24V fans are not running, the first thing to consider is whether the switching power supply is damaged.