Simple and practical method for preventing the firing of the gun when the inverter is inspected and repaired - Solutions - Huaqiang

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When repairing the faulty inverter, no matter whether it is found after the fault is detected or after the repair, it must pass the actual test of the power-on test. I have experienced several times of power-transmitting inverter when I first learned to repair the inverter. As for the shooting, not only is it scary to make people feel unsafe, but firing can make the faulty inverter more serious and more difficult to repair.
How to solve this problem? Later, I came up with a way to fix a 100W incandescent bulb to each phase behind a three-phase AC 380V power switch on the power supply panel. This method of string bulbs has also been seen on the online information. The difference is that the inverter is repaired and the bulb is serially connected to the DC main circuit of the inverter. Although it can also prevent the DC loop of the inverter from being short-circuited, it is protected. The range is smaller than the previous method, and it is also a little troublesome to use.
After using the power string bulb method, I was much more confident when I sent power to the inverter. If the inverter is really fault-free or repaired, after the power is supplied, the three bulbs will be flashed evenly due to the capacitance of the inverter, and then extinguished. If only two lights are flashing, the inverter is out of phase for some reason, and the phase lamp that is out of phase will not light. Therefore, the fault of the inverter phase loss can be found. If the brightness of the three bulbs is dark and the time is short, it may be that the capacity of the main circuit DC electrolytic capacitor of the inverter becomes smaller, so the charging current becomes smaller, so this method can not only prevent short circuit, but also help to judge some of the inverter. Basic working conditions, especially when testing a tens of KW high-power inverters indoors, there is a need to connect the bulbs in series without having to access a power source with a large power, which will have a sense of security. Just pay attention to the time of charging and discharging after power transmission or power failure will be extended with the increase of the power of the inverter. I am in the main DC circuit and put on a 30-40W electric soldering iron during discharge, which can speed up Discharge speed.
When the power is turned on, the inverter should not be connected to the load. After the power is turned on, check the fan and the panel display operation is normal. The frequency of the inverter can be adjusted from low to high. Use a multimeter to measure whether the output voltage of U, V, W is balanced and the amplitude is normal. . I use a small 1KW motor to load the indoors. Although the power supply circuit is connected in series with the bulb, the actual inverter with the capacity below 4KW can be directly driven. If the power is increasing, the pressure reduction of the bulb is caused. The inverter will issue a low pressure alarm.
In short, this method is relatively simple and practical, especially for beginners who have little experience in maintenance and are relatively rudimentary.