Abstract : This paper introduces the problems encountered by users when using Fuji inverters and their corresponding countermeasures. Keywords : Inverter application, fault countermeasures 1 Introduction In the past ten years or so, with the transformation of a large number of industrial infrastructure equipment, especially in the field of control, more and more users have put forward higher requirements for the control methods of electrical equipment, which has led many users to choose inverters. This paper combines its own work experience to provide corresponding countermeasures for the problems encountered by users when using Fuji inverters. [b]2 Main Circuit 2.1 Main Circuit Power Input Terminal[/b] (1) As shown in Figure 1: The main circuit power terminal is connected to the three-phase AC power supply through a circuit breaker for line protection or a circuit breaker with leakage protection. (2) In order to cut off the power supply and prevent the fault from expanding when the inverter protection function is activated, an electromagnetic contactor should be connected in the power supply circuit to ensure safety. 2.2 Commonly Encountered Problems (1) Power supply tripping. Many users in China mistakenly connect (N-) as the ground wire, so the circuit breaker will trip when the power supply is activated. (2) If the power supply capacity is greater than 500kVA or 10 times the capacity of the inverter, the voltage difference of the power grid may cause the rectifier module to break down and trip when power is supplied. This type of problem generally needs to be solved by adding an AC reactor at the input end. (3) If a fault occurs suddenly during operation and “FUS” is displayed, it indicates that there is a short circuit inside the inverter. This may be due to environmental noise causing the gate trigger pulse to be falsely triggered, resulting in incomplete turn-off and causing the upper and lower bridges of the IGBT module to be directly connected and short-circuited. The solution is to add two noise limiters (upper bridge and lower bridge) at the front end of the gate trigger signal line to prevent interference and false triggering. (4) Main circuit insulation test. If “EF” is displayed as a short circuit fault to ground, it is necessary to test whether the insulation of the inverter is good. The specific steps are as follows: ① Use a 500VDC megohmmeter to test under the condition of disconnecting the main power supply. ② Disconnect all control circuit connections to prevent the test voltage from entering the control circuit. ③ Connect the main circuit terminals with a common line as shown in Figure 2. ④ The megohmmeter voltage should only be applied between the main circuit common connection line and ground. ⑤ A megohmmeter reading ≥ 5MΩ is considered normal and acceptable. [b][align=center]For more details, please click: Common Inverter Faults and Countermeasures[/align][/b]