During the daily operation of frequency converters, the proportion of overcurrent faults reported by frequency converters accounts for approximately 40% to 45% of the total faults of frequency converters, which is a common and frequently-occurring fault of frequency converters. For the current types of frequency converters, their overcurrent protection functions mostly include three major categories: short-circuit faults, overcurrent during acceleration/deceleration, and overcurrent at constant speed. In the process of actual use or repair, if current fault inverter quoted from two aspects:

1. External reason

This aspect mainly includes fault phenomena such as burnout of the motor windings driven by the frequency converter and short circuit of the cables on the load side.

2. Reasons related to the inverter itself:

When the current sampling components inside the inverter, as well as the subsequent rectification, shaping, comparison circuits, or the electronic circuits for detecting IGBT/IPM power modules, experience abnormalities, or if the power inverter module itself has a breakdown fault, it will also cause an overcurrent fault in the inverter. From this, it is easy to see that the simplest way to distinguish the causes of the inverter's overcurrent fault is to disconnect the inverter from the load and conduct a separate power-on test on the inverter or the motor. In this way, the cause of the fault becomes clear at a glance. 

3. Frequency converter overcurrent fault

The common overcurrent phenomenon in frequency converters mainly occurs in the following three aspects:

(1) The inverter reported an overcurrent fault upon power-on.

In most cases, this situation cannot be reset. The main reasons for this are: IGBT/IPM module damage, abnormal drive signals, and faults in the current detection circuit. In such cases, the inverter must be repaired promptly to prevent the fault from escalating.

(2) When the frequency converter is powered on and in standby mode, it displays normally. However, as soon as it starts running, it reports an overcurrent fault.

The reasons for this situation mostly lie in the external driven load motor of the frequency converter, as well as mechanical transmission mechanisms getting stuck, etc. Under such circumstances, it is strictly prohibited to repeatedly test the frequency converter without resolving the problem. Otherwise, it will not only be a problem with the peripheral machinery!

(3) The frequency converter started normally at the beginning, but reported overcurrent during the acceleration process.

The main reasons for this are mostly related to the excessively short acceleration time setting of the frequency converter, the incorrect setting of the motor's rated current value which is too small compared to the actual situation, and improper settings such as the torque compensation (U/F) setting and others.