Reasons for frequent tripping of earth leakage protectors in variable frequency speed control systems and their solutions

In the variable frequency speed regulation system, in many cases, leakage protectors (RCDs) are used, some of which must be added in accordance with relevant standards/norms, and some must be added by Party A’s requirements. In the high-speed system, it is often encountered that after the inverter is powered on, the leakage protector will frequently act, resulting in the failure of the variable frequency speed control system to operate normally.

Inverter leakage current

The root cause of the leakage current of the inverter is the working principle of the inverter. The frequency converter uses Pulse Width Modulation (PWM) to continuously control the speed of the motor, in the process, it will generate a leakage current with a frequency far greater than 50Hz.

In addition, the internal interference suppression measures of the frequency converter and the parasitic capacitance in the cables connected with the frequency converter and the motor are also one of the reasons for the leakage current in the frequency conversion speed control system.

The commonly used methods to reduce the frequent action of the leakage protector in the variable frequency speed control system are as follows:

1. Distinguish the circuit that needs the protection of the leakage protector from the circuit that does not need the protection of the leakage protector

2. Distinguish the cable with the filter installed from the cable without the filter installed

3. Shorten the length of the connecting wire between the inverter and the motor

4. Install the high-performance MLAD-VR-SR inverter dedicated input reactor to suppress the Du/Dt on the power supply side of the inverter

5. Select the leakage protector with delay characteristic

6. Set a filter on the grid side, do not set the inverter-specific input filter on the power supply side of each inverter in the variable frequency speed control system

7. Use the three-phase four-wire inverter-specific input filter to replace the three-phase three-wire inverter-specific input filter

8. Install the special sine wave filter for MLAD-SW inverter

9.Select the inverter-specific input filter and inverter-specific output filter with low leakage current

www.shuyitop.com;

Tel/Fax: 0086-577-62840011

WhatsApp: 008613355775769

#VFD  #INVERTER  #frequencyinverter  #frequencyconverter

#converter  #inverters  #vfds  #vfdmarket  #ZJSHUYI  #chinashuyi