Looking at: 

Through visual observation, it can be seen that there is no burning sign of components on the circuit board, there is no splash, drum top, deformation of the main circuit energy storage capacitor, there is no crack in the rectifier module and inverter module, there is no ignition burning trace at the terminal connection of the device, etc. Shake the converter box, listen to the sound, or there is no damaged device residues poured out from the box;  Smell whether there is burnt smell, determine the part of the circuit that emits burnt smell;  For capacitor leakage, module breakdown and explosion and other faults. 

If there is a black fire, the possibility of damage to the converter is very large, which means that the main components of the converter are burned out. 

Smell: 

Using people's sense of smell, according to the smell of the frequency converter can also judge the fault.  Such as overheating, short circuit, breakdown fault, it is possible to smell burnt smell, smoke smell and plastic, rubber, paint and other heat volatilized smell. 

Q: 

When the frequency converter failure, maintenance personnel and doctors to see a doctor, first to understand the detailed "condition".  That is, to equipment operators or users to understand the use of frequency converter, frequency converter medical records and the whole process of failure. 

When taking over the faulty inverter for repair, we should first communicate properly with the user for repair, master the use of equipment and the cause of failure, so as to facilitate targeted repair and reduce the failure repair rate. 

— Cause of equipment damage, in operation, or in the process of slowing down and stopping, or caused by abnormal load, etc. 

— The power supply of the equipment, whether the three-phase power supply is balanced, there is no phase, voltage is too high. 

— Load condition, the working condition of the load motor, whether it is a large inertial load (such as fan, centrifuge), whether there is a requirement for timing deceleration and stop, or DC brake control, whether brake unit is installed, etc. 

— The equipment has trouble-free maintenance experience, whether the same fault phenomenon is repeatedly sent for repair in a short period of time. 

— The operating environment of the equipment. Whether the temperature is too high or too humid. 

Due to abnormal power supply, the rectifier module is repeatedly damaged, and the equipment is sent for repair. Relevant measures must be taken to solve the power supply problem, so as to fundamentally prevent frequent damage of the inverter. 

The success of maintenance depends not only on the maintenance itself, but also on the cooperation and participation of users. Cooperate with users to deal with (or put forward relevant suggestions) field application problems, often can greatly reduce the failure repair rate. 

Cut: 

Measuring the multimeter as their "eyes", without removal of frequency converter, measure the inverter main circuit terminal - power input terminals R, S, T, U, V, W output voltage terminals, P, N dc circuit terminal between positive and negative resistance, can "see" a rough idea of the main circuit of damage,  And first detect and then power on (to avoid the main circuit has a serious short circuit fault when the power on precipitously), but also maintenance must develop a good habit. 

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