Inverter fault repair example Wang Wenchao high-pressure oil-less circuit breaker hot oil circulation drying method Pan Jiamin inverter, there are nearly 100 sets of various types of inverters. Recently, inverter faults have gradually appeared, and it is deeply felt during the process: the faults of the inverter are mostly caused by peripheral equipment and line faults, and the faults mainly occur in the main circuit, the drive circuit and the detection circuit. In the following, combined with the inverter circuit (as shown in the drawing), several examples are introduced for the reader.
Example 1 The inverter (Sanken SVF113, llkVA) could not start the motor (Y132S-4, 5.5kW), and the fault was displayed as "4". It is known from the manual that the fault display "4" is an overcurrent or an inverter module failure. Then disconnect the inverter output line, first check the motor with a megaohm meter and find that the motor has burned. After the inverter is powered, the inverter still shows that the main circuit 30A fast fuse is open, and the inverter module may also be damaged. Open the inverter panel, remove the main control board, check the fuse, and it has been broken. Then use the multimeter diode characteristic file to check the three inverter modules, and find that the e pole and the c pole of one transistor in one module are short-circuited. Then measure the b pole and the c pole, which is also a short circuit. Further analysis: b-pole and c-pole short circuit, it is possible to damage the drive circuit. Check the output impedance of the six-way drive circuit on the main control board, and surely one of the triodes is damaged. After replacing the triode, module, and fast-melting, the power transmission is running and the inverter returns to normal.
Example 2 Inverter (Published PI89, 5.5kW) fault is displayed as "OC" D According to the inverter manual, "OC" means overcurrent 5.5kW) three-phase winding, the resistance value is balanced and the insulation is good. Disconnect the inverter output line, and then power on, measure the output voltage of the inverter U, V, W, the three-phase voltage balance, but the voltage value is too small. After analysis, the above phenomenon occurs only when the DC link voltage of the inverter is insufficient. The DC voltage between the P terminal and the N terminal of the inverter is re-detected, only 340V, thereby estimating the fault of the three-phase rectifier bridge. Open the panel and take off the main control board. It is really a plug-in input terminal of the three-phase rectifier bridge that burns out due to poor contact, making it a single-phase bridge, causing insufficient DC voltage, resulting in three inverter outputs. The phase AC voltage is too small. The three-phase asynchronous motor must have an overcurrent when the load is constant and the voltage is insufficient, so the inverter displays “OCâ€. After replacing the rectifier bridge, the inverter runs normally.
The oil quality index of the 110-type oil-less circuit breaker is far exceeding the standard. After the oil change treatment, the leakage current is reduced, but it is still exceeding the standard. It is estimated that the inside of the circuit breaker, especially the lifting rod, is seriously affected by the tide.
If it is disintegrated, it is too time-consuming and laborious to send the lifting rod to the oven. We have adopted the hot oil circulation drying method and achieved good results.
The specific method of hot oil circulation drying is shown in the attached drawings. Pump the oil in the circuit breaker into a large-sized oil tank of appropriate size and add a portion of the replenishing oil. The vacuum oil filter is used to continuously heat and filter the oil circulation in the oil tank. Since the oil quantity is not much, the oil temperature rises faster. Then use a small oil filter (50L/min) to heat the oil at 5.5kW). There is noise and vibration when the low frequency is no-load. When the frequency rises, the motor seems to be running normally, but when the motor is loaded, the inverter (Sanken SVF113, llkVA) shows tk "3", that is, "overload". Check that the motor is normal, drag it with another inverter, and the load can run normally, indicating that the problem is in the inverter itself. Check the output voltage and find that the three-phase voltage is unbalanced. After analysis and inspection, one bridge arm of one module of the inverter is broken. The reason for the above phenomenon is: because the U, V, W terminals of the inverter output three-phase unbalanced AC voltage, an elliptical rotating magnetic field is generated in the stator of the motor, causing noise when the motor is low-frequency and no-load starting, neither like normal starting. It does not start like a complete phase loss; after the frequency goes up, the motor speed also goes up. Because of the inertia of the motor rotor, the motor operation seems normal; when the motor is loaded, the motor current is too large due to the two-phase undervoltage. The display shows “3â€, which looks like an overload, which is a fault of the inverter.
(Edit Wei Ming) take turns to inject from the two columns and the triangular cavity of the circuit breaker, and the oil drain valve is connected to a fuel pipe to let the oil flow back into the oil tank. If the oil flows out slowly, it can be divided several times and D is repeated. In order to achieve the effect of flooding, the oil should not be aged. The oil temperature should be controlled at 70~80=笥笥绱çƒé”Š~4hD If the circuit breaker is seriously wet, the time can be extended appropriately (if the moisture is too severe, it needs to be disintegrated. In addition, to do the circuit breaker leakage current test should pay attention to the micro-ampere meter should be connected to the rolling side, the micro-ampere to the circuit breaker lead must use shielded wire, and the shielding layer Connect to the power supply terminal of the micro-ampere meter to eliminate the effects of corona current and interference current. We have to measure the leakage current of the circuit breaker. The high-voltage lead wire uses the plastic copper core wire instead of the shield wire, and the high-voltage lead wire is vacant (no circuit breaker is connected). The indication of the micro-ampere meter actually exceeds 40.
(Finish)
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