First, the frequency converter maintenance method
captive test
1, test the rectifier circuit.
Looking for the result, it can be judged that the circuit is abnormal. A. Turn to the P terminal and N terminal of the DC power supply inside the inverter, and adjust the multimeter to the resistance of X 10. The red meter bar is connected to P, and the black meter bar is connected to R, S and T respectively. Under normal circumstances, there are tens of ohms of resistance, which is basically balanced. On the contrary, the black bar is connected to the P terminal, and the red bar is connected to R, S and T in turn, and the resistance value is close to infinity. Connect the red observation bar to the N terminal and repeat the above steps, all of which should get the same result. If the resistance is unbalanced in three phases, the rectifier bridge is faulty. B. When the red bar is connected to the P terminal, the resistance is infinite, so it can be concluded that the rectifier bridge is faulty or the starting resistance is faulty.
2. Test the inverter circuit
The red bar is connected to the P terminal, and the black bar is connected to the U, V, and W terminals respectively, with a resistance of several tens of ohms. The resistance of each phase is basically the same, and the reverse phase is infinite. Repeat the above steps for the N end of the black instrument strip and get the same result, otherwise it can be determined that the inverter module is faulty.
dynamic test
After the static test results are normal, the dynamic test can be carried out, that is, power-on debugging. Attention must be paid to the following points before and after power-on:
1, you need to confirm whether the input voltage is wrong before powering on. When the 380V power supply is connected to the 220V inverter, there will be machine explosion (explosion capacitor, explosion rheostat, explosion module, etc. );
2. Check whether the sockets of the frequency converter are connected correctly and whether the connection is loose. Abnormal wiring may sometimes lead to inverter failure, and in serious cases, the machine will explode.
3. Detect the fault display content after power-on, and preliminarily judge the fault and its causes;
4. If the fault is not displayed, first check whether the parameters are abnormal. After the parameters are reset, start the frequency converter with no load (without connecting the motor) and test the output voltage values of U, V and W. If the three phases are out of phase and unbalanced, the module or the driving board will fail.
5. When the output voltage is normal (no phase, three-phase balance), the load test should be as full as possible.
Fault judgment
1. The rectifier module is damaged.
Usually caused by grid voltage or internal short circuit. Replace the rectifier bridge under the condition of eliminating the internal short circuit. When dealing with faults on site, it is important to check the situation of the user's power grid, such as the voltage of the power grid and whether there are welding machines and other equipment that pollute the power grid.
2. The inverter module is damaged
It is usually caused by motor or cable damage and drive circuit failure. After repairing the drive circuit, replace the module when the drive waveform is in good condition. After replacing the drive board in the field service, pay attention to check the motor and connecting cables. Only when there is no fault can the frequency converter run.
3. Don't display it when it is turned on.
Usually, the DC circuit has no DC power due to the damage of switching power supply or soft charging circuit. If the starting resistor is damaged, the operation panel will also be damaged.
4. Display overvoltage or undervoltage
Generally, it is caused by lack of input phase, aging circuit and damp circuit board. The solution is to find out its voltage detection circuit and detection point and replace the damaged device.
5. Overcurrent or short circuit to ground is indicated.
Usually due to the damage of the current detection circuit. Such as Hall element, operational amplifier circuit, etc.
6. The power supply and the driving board began to show overcurrent.
This is usually caused by damage to the drive circuit or inverter module.
7. No-load output voltage is normal, and overload or overcurrent is displayed after load.
It is usually caused by improper parameter setting, aging drive circuit and module damage.
The above examples we give you are about the treatment methods and detection steps of inverter maintenance. Therefore, if the inverter has a series of fault problems, the first operation is to cooperate with professional tools for detection. For example, referring to the above, there are many suggestions that can be learned, including detection skills and follow-up treatment and maintenance methods. Of course, if you have no experience for the first time, it may lead to some inevitable troubles. At this time, Bian Xiao thought that he could consult some professionals or ask professional institutions for surgery.
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