Multimeter test inverter rectifier bridge good or bad method
With a multimeter resistance block can determine the damage of the inverter rectifier bridge, the parallel rectifier bridge to loosen the connectors, find the bad one.
1, test the rectifier circuit
The multimeter will be adjusted to the resistance X10 file, the red pen to the P terminal, the black pen to the R, S, T terminal, there should be about tens of ohms of resistance, and the basic balance. Connect the black pen to the P terminal, the red pen to R, S, T in turn, there is a resistance value close to infinity. The red pen to the N terminal, repeat the above steps, should have the same result. If the resistance value of the three-phase imbalance or the red pen to the P terminal, the resistance is infinite, it can be determined that the circuit has been abnormal, rectifier bridge failure.
2, test the inverter circuit
The red pen to the P terminal, the black pen to U, V, W, there should be a few tens of ohms of resistance, and the resistance value of each phase is basically the same, will be connected to the black pen to the P terminal, the red pen to the U, V, W, there is a close to infinity of the resistance value. The black pen to the N terminal, repeat the above steps, should get the same result, otherwise you can determine the inverter module failure.
In the rectifier circuit and inverter circuit test is normal, only after the power test. Before and after power-on according to the contents of the fault display, to determine the fault and the cause.
Damage cause analysis:
(1) The device itself is of poor quality;
(2) The rear stage circuit and inverter power switching device are damaged, resulting in the rectifier bridge flowing through the short-circuit current and damage;
(3) The grid voltage is too high, and the grid encounters lightning strikes and overvoltage surges. The internal resistance of the grid is small, and the varistor for overvoltage protection has burned out and does not work, resulting in all the overvoltage added to the rectifier bridge;
(4) inverter and grid power transformer is too close, the line impedance in the middle is very small, the inverter is not installed DC reactor and input side AC reactor, so that the rectifier bridge is in the capacitive filtering of high amplitude sharp pulse current impact state, resulting in premature damage to the rectifier bridge;
(5) Input phase loss, so that the rectifier bridge burden and damage.
Find the root cause of rectifier bridge damage, and eliminate, prevent the replacement of the new rectifier bridge and damage.
(1) Replace the new rectifier bridge, the welding of the rectifier bridge need to ensure that the welding is reliable. Ensure that the electrical safety with the peripheral components of the spacing, screw coupling should be tightened to prevent contact resistance and heat. With heat sinks have conduction heat conduction, require a good coating of silicone grease to reduce thermal resistance;
(2) The parallel rectifier bridge to use the same model, the same manufacturer's products to avoid uneven current and damage.
1. Half-bridge detection half-bridge is composed of two rectifier diodes, by using a multimeter to measure the two diodes inside the half-bridge positive and negative resistance value is normal, you can determine whether the half-bridge is normal.
2. full-bridge detection of most of the rectifier full-bridge, are marked with "+", "-", "~" symbols (including "+") " for the positive pole of the rectified output voltage, "-" for the negative pole of the output voltage, "~" for the AC voltage input), it is easy to determine the electrodes.
Detection, by measuring the "+" pole and the two "~" pole, "-" pole and two "~" Between the rectifier diode positive and negative resistance value (and ordinary diode measurement method is the same) is normal, you can determine whether the full bridge has been damaged. If the measured full-bridge whip diode positive and negative resistance values are 0 or infinity, you can judge the diode has been broken or open-circuit damage.
