Type of Residual Current -What Do You Know?

The International Electrotechnical Commission (IEC) classifies residual currents primarily by their waveform characteristics. Based on these, residual currents are categorized into four main types: Type AC Residual Current, Type A Residual Current, Type F Residual Current, and Type B Residual Current.

Type AC residual current

AC type residual current protector can only ensure tripping for residual sinusoidal alternating current that is suddenly applied or slowly rising. It is a typical sinusoidal alternating current, so its waveform is a sine wave.

Type A residual current

Type A residual current refers to the residual current of pure sinusoidal AC and pulsating DC. The waveform characteristics are AC, and the principle of generation is very simple, that is, leakage occurs at the AC voltage.

It mainly includes the following types of residual current:

Residual current with a current lag angle of 0° (abbreviated as A0°): The waveform characteristics are pulsating DC after half-wave rectification, and the corresponding leakage occurs after half-wave or full rectification.

Residual current with a current lag angle of 90° (abbreviated as A90°): The waveform characteristics are the right half of the A0° waveform (90°~180° part), and the corresponding leakage occurs after half-wave or full rectification, and the rectification lag angle is 90°.

Residual current with a current lag angle of 135° (abbreviated as A135°): The waveform characteristics are the right half of the A90° waveform (135°~180° part) , the corresponding leakage occurs after half-wave or full rectification, and the rectification lag angle is 135°.

The current lag angle is 0° and the residual current of 6mA smooth DC is superimposed (abbreviated as A0°+6mA): The waveform feature is that the A0° waveform is raised by 6mA by DC. In this case, leakage generally occurs on multiple loads, one load leakage occurs after rectification, and one load leakage occurs after filtering.

The pulsating DC residual current generated by the two-phase power supply rectifier circuit (abbreviated as 2PDC): The waveform feature is that there are two half-wave rectification peaks in one cycle (20ms), with a 0 point, and the corresponding leakage occurs after the two-phase power supply rectification. “

Type F Residual Current

Type F Residual Current: refers to the residual current at the composite frequency of type A and multiple harmonic components. The frequency of these currents may not be fixed and contain multiple harmonic components.

150Hz AC residual current: The waveform characteristics are AC, the frequency is 150Hz, and the corresponding leakage occurs at the AC output of the inverter.

400Hz AC residual current: The waveform characteristics are AC, the frequency is 400Hz, and the corresponding leakage occurs at the AC output of the inverter.

1000Hz AC residual current: The waveform characteristics are AC, the frequency is 1000Hz, and the corresponding leakage occurs at the AC output of the inverter.

Compound residual current: The waveform characteristics are a mixed waveform of multiple ACs.

Type B Residual Current

Type B Residual Current: refers to all residual current waveforms of AC type, A type, F type and smooth DC.

AC superimposed DC residual current (AC+DC for short): The waveform feature is that the AC waveform is lifted by DC. In this case, leakage generally occurs on multiple loads, one load leakage occurs at the AC voltage, and one load leakage occurs after filtering.

Pulsating DC residual current generated by the three-phase power supply rectifier circuit (3PDC for short): The waveform feature is that there are three half-wave rectifier peaks in one cycle (20ms), no 0 point, and the corresponding leakage occurs after the three-phase power supply rectification.

Smooth DC residual current (SDC for short): The waveform feature is smooth DC, and the corresponding leakage occurs after rectification and filtering. Due to the existence of filter capacitors, the leakage is DC.

All 150Hz, 400Hz, 1000Hz AC residual currents”

Conclusion

After understanding so many residual current waveform features, are you worried that the leakage protector can really play a protective role? Is there any equipment that can provide comprehensive leakage protection? Blue Jay leakage current and residual current protection relays can provide comprehensive protection for different residual current environments and are widely used in various industries of industrial power automation.