Why Is DC 6mA Used In AC EV Charger?

What is RCD dc 6mA ?

6mA DC RCM (Residual Current Monitor) is nothing new for professional electricians installing EV charging piles in Europe. The device is widely integrated into EV charging piles to detect smooth DC residual current. However, some people may ask why a DC RCM is used in an AC EV charger rather than in a DC EV charger.

Residual current devices protect your safety switches. They provide protection in three ways, i.e., fire protection, fault protection, and additional protection.

  1. Fire protection for currents of higher mA, usually more than 300 mA
  2. Fault protection for tripping currents
  3. Additional protection for currents with lower mA less than 30 mA

What causes DC residual current when charging an electric vehicle?

The following diagram shows the electrical structure of a typical on-board charging system (OBC). The system consists of an input EMI filter, an AC/DC rectifier, a PFC, a DC/DC power converter, and an output EMI filter. During the use of electric vehicles, the vibration and aging of components will inevitably occur, which will lead to the failure of OBC insulation.

What are the risks of smooth DC residual current when charging an electric vehicle?

Level 1 charger uses a 120V AC plug and simply plugs into a standard power outlet. This can be done using a Level 1 EVSE cable that has a standard three-conductor household plug for receptacles and a standard J1722 connector for vehicles on one end. When connected to a 120V AC plug, charging rates range from 1.4kW to 3kW and may take 8 to 12 hours, depending on battery capacity and condition.

The smooth DC residual current caused by the OPC insulation fault will affect the normal function of the Type a 30ma RCD installed in the AC EV charging pile power supply line or in the AC EV charging pile. In other words, when DC fault currents above 6 mA occur, the response time and response level of Type a RCDS are negatively affected. In the worst case scenario, Type a RCDS will no longer trip over in the event of an electrical accident.

RCD Composition and operation

The residual-current device is designed with a coil around a wire. Residual current device monitors ground leakage and provides safety protection.

Residual current devices are based on two different technologies. One is electromagnetic and the other is electronic. Both technologies provide excellent performance. Electromagnetic equipment is strong enough to detect very small residual currents and does not require lead grounding. The temporary power outage did not affect them. Electronic devices, on the other hand, are relatively low in strength, so they need ground lead to perform well during power outages.

The application of DC 6mA in charger

This 6mA RCD module detects DC currents flowing in an AC system. For example , in electric vehicle charging station,DC currents flowing in an AC system may cause a Type A RCD to be blinded. This RCD module can be used to detect any DC currents level above 6mA and its output can be used to operate a relay or contactor to disconnect the AC supply and prevent blinding of the upstream A type RCD.

According to standard GB/T 187487.1, the leakage protector of the charger should use type B or type A,in addition to the AC leakage protection, but also to pulase DC protection.

The biggest difference between type B and type A is that type B increase the protection of DC leakage. The biggest harm of DC leakage does not lie in the human body, but in potential failure of the original leakage protection devices.

Zencar ev charger Type B AC30mA DC 6mA

In order to meet the needs of most European markets, Zencar has introduced several new chargers with DC 6mA, from IEC61851 to IEC62752. It protects the charger, the car, and the people who use it. The following several chargers are to meet the latest standards IEC62752

ModelType A/B
Model AA
Model BB
Model CA
Model DB
Model EB
Model E PROB

Model E ev charger

Current: 16A/32A

Voltage: 230v/380v


1.adjustable amp

2.Delayed timer setting

3.Ground detection

Model D ev charger

Current: 16A/32A

Voltage: 230v/380v


1. Type B RCD(AC 30mA +DC 6mA)

2. adjustable amp

3. electricity storage memory 1 million kwh

4. Repeat timer setting

5. Bluetooth lock function

6. Big screen

22kw EV charger

Model E Pro ev charger

Current: 16A/32A

Voltage: 230v/380v


1. Type B RCD(AC 30mA +DC 6mA)

2. adjustable amp

3. electricity storage memory

4. real-time monitoring of charging status

5. Biggest screen

6. App/wifi application

  1. Make an appointment , this feature will be important for you any time you want to charge it, when you get home from work and want to make an appointment for the night when your electricity bill is cheapest.
  2. Save your battery log so you can see how many kilowatt-hours you are using at any time.
  3. Wait for yourself to use the process to find out, it will be a surprise to have a Zencar AC ev charger!