Why must the European standard charging pile control board use Type B RCD? Can Type A + DC detection module not replace it?

The control board of European standard charging piles must use Type B RCDs. This is not an "extra flourish" but a mandatory requirement where "DC leakage current" is explicitly listed as a compulsory inspection item. Type A (even with an additional 6 mA DC detection module) cannot serve as an equivalent substitute for three reasons:

1.The standard text specifies "must be Type B."

• IEC 61851-1:2017 Clause 7.3 Table 5 Footnote b:

• Mode 3 AC charging piles shall use Type A or Type B RCDs; however, only Type B is acceptable when a smooth DC residual current ≥ 6 mA may occur.

• IEC 62955 and IEC 62752 directly classify "electric vehicle charging" as a DC-sensitive load, excluding Type A.

2.The rectification of the onboard OBC will inevitably generate a smooth DC leakage current of 10–200 mA

• The three-phase PFC topology generates a DC component of 50–150 mA superimposed on the PE line under full load; the A-type core exhibits a trip value drift after DC pre-magnetization, and can refuse to trip with a current ≥ 6 mA.

• Field Measurement: Using an A-type + external 6 mA DC detection module, when the DC leakage current rises to 35 mA, the tripping time extends from 40 ms to over 2 s, exceeding the 0.3 s limit for personal safety.

3.Type B RCD requires "full waveform+high frequency" coverage to obtain CE certificate

• T Ü V Witness Test Project:

1.  50 Hz sine AC 30 mA

2.  Pulsating DC 90 °/135 ° 30 mA

3.  Smooth DC 30 mA

4.  1 kHz+30 mA

Only Type B (flux gate+dual winding demodulation) can pass all four terms simultaneously; Type A fails directly in ③ and ④, and is judged as unqualified by the laboratory.

Conclusion

Type A+external 6mA DC detection board can only provide warning and cannot perform tripping; European regulations also include "trip execution" in the safety chain, so it cannot replace B-type RCD. To obtain certificates such as CE, UKCA, TIS 1693, etc., B-type flux gates or B-type RCCBs must be included in the BOM of the charging station control board - this is the hardware red line, and there is no software or module solution to bypass.

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