Converter and inverter technology is the application of microelectronic technology, a power control device for controlling the AC motor by changing the frequency of the motor operating power mode.

The main drive motor is used to adjust the speed, there are two aspects of the application:

1. Energy is mainly fan and pump load, the frequency converter using direct power than the power grid, so that energy saving, energy saving can reach a ratio of more than 50%, the energy saving effect of the process on specific operation of the motor. Often a large number of energy-saving motors can be run at low speeds, if the motor is always running at full capacity, it is also no need to use the drive.

2. The process requirements, in metallurgy, petroleum, chemical, textile, electricity, building materials, coal and other industries, some technology does not allow direct motor starting, we need to meet the technological requirements of Frequency Control and coordination. This is a must drive. Such as metallurgical industry need drive motor about 70%.

In the course of the drive, a short-circuit failure occurs. So, what are the reasons of the inverter is short-circuited?

1. The inverter short-circuit failure usually occurs during operation, when the reset start again, the speed control system increases the speed of the drive inverter short circuit protection.

2. Drive a short-circuit failure has a great impact on current, modern inverter has no time limit quick break protection, when a short circuit fault, as long as no time limit quick break protection and reliable action, would not have caused the short circuit current inverter damage. Since no protective action time of speed off very rapidly, it is difficult to observe the size of the short-circuit current, and therefore provided for the fault record inverter fault parameters can be obtained in the record.

3. The short-circuit the output side of the inverter output to drive mainly in short circuit protection of which a substantial part of the connection cable between the motor phase short circuit occurs inside the motor short circuit or the like, cable and motor failures account.

4. The frequency converter itself is not working properly, as abnormal two inverter devices in the inverter bridge of the same bridge arm continues to appear in alternating operation. For example, the ambient temperature is too high or the inverter device itself aging and other reasons, so that the inverter device parameter changes, resulting in the alternate process, a device has been turned on, the other device has not yet had time off, causing the same an upper arm, the two devices "through", the positive DC voltage, between the negative electrode are short-circuited.