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Ten common senses of frequency converter protection for motors

Time: 2020-09-23

As we all know, frequency converter adjusts the voltage and frequency of the output power through the interruption of internal IGBT, and provides with the required power supply voltage according to the actual needs of the motor, thereby achieving the purpose of energy saving and speed regulation. What are the ways and measures for the frequency converter to protect the motor? Let's take a look at it together!

1.Over-voltage protection

The output of the frequency converter has a voltage detection function. It can automatically adjust the output voltage so that the motor does not bear over-voltage and the motor could run within the set voltage range.

2.Under-voltage protection

When the voltage of the motor is lower than 90% of the normal voltage (some set to 85%), the frequency converter protects and stops.

3.Over current protection

When the current of the motor exceeds 150% of the rated value for 3 seconds, or 200% of the rated current for 10 microseconds, the frequency converter protects the motor by stopping.

4.Open-phase protection

When the output is lacking a phase., the frequency converter will alarm, and the frequency converter will stop immediately to protect the motor.

5.Phase-reversal protection

The frequency converter can be set it that the motor can only rotate in one direction, and the rotation direction cannot be set. Unless the user changes the phase sequence of the wiring of the motor A, B and C, there is no possibility of inverting the phase.

6.Overload protection 

The frequency converter monitors the motor current. When the motor current exceeds 120% / 1 minute of the set rated current, the frequency converter will stop to protect the motor.

7.Ground protection

The frequency converter is equipped with special ground protection circuit, which is generally composed of ground protection transformer and relay. When one or two phases are connected to the ground, the frequency converter will stop immediately. Of course, if the user requires, we can also be designed for immediate safety protection after grounding.

8.Short-circuit protection

After the output of the frequency converter is short-circuited, it will inevitably cause over currency. The frequency converter will protect the motor by stopping within 10 microseconds.

9.Overclocking protection

The frequency converter has the maximum and minimum frequency limit function, so that the output frequency can only be within the specified range, thereby realizing overclocking protection function.

10.Stalling protection

Stall protection is generally aimed at synchronous motors. For asynchronous motors, the stall during acceleration must be manifested as over currency. The frequency converter realizes this protection function through over currency and overload protection. Stall during deceleration can be avoided by setting a safe deceleration time during commissioning.