Why choose Type B sensor for leakage protection of European standard AC charging pile？

 

 

1.Residual current is more complicated and prevention is more urgent

Residual current monitoring and its popularization can be traced back to around 1990. The earliest was Type AC, and now Type B residual current monitoring has been gradually adopted in many fields . Its inclusion relationship is shown in Figure 1. It is precisely because of the complexity of electrical equipment and circuit topology that residual current monitoring has developed from Type AC to the current Type B. The definition of Type B residual current includes Type AC, Type A and DC residual current, so Type B residual current detection is currently a relatively high requirement for residual current detection. Type B refers to smooth DC and intermittent DC on the basis of Type A leakage (AC, jumping DC, half-wave AC).

Figure 1 Schematic diagram of different power networks and residual current

 

 

 

2.Formation of smooth DC leakage

In the AC charging pile system, leakage current exists in the form of AC, pulsating DC, pure DC and some high-frequency current. There are several reasons why electric vehicles may have the risk of contact with electricity when charging.

(1) Danger of discontinuity of protective ground wire.

(2) The cable insulation layer is damaged.

(3) Electric vehicles may come into contact with active components of the vehicle charger due to accidents, maintenance, etc.

(4) Humid and corrosive environment causes leakage.

(5) Damage to components causes leakage.

 

 

 

3.Necessity of DC leakage protection

To understand why smooth DC 6mA is needed for DC leakage protection, we need to start from standards and safety. The essence of leakage current protection of charging piles is introduced in the IEC61851 standard, namely “Protection against electric shock”. Neither domestic nor foreign safety standards set smooth DC 6mA as the human safety protection current, because such a small current will not cause harm to the human body. The reason for detecting it is also very simple. The excessive presence of smooth DC components will cause the A-type magnetic ring to saturate prematurely, and ultimately cause the A-type leakage protection to inaccurately detect AC leakage.

In the existing European standard pile market, for the upgraded leakage protection mode, the existing application processing methods are roughly the following:

 

 

 

 

1.Type B leakage protection solution

Disadvantages: expensive, large size, low accuracy, poor anti-interference ability

 

 

 

 

2.Type B leakage current sensor solution (Type B-Sensor)

HEYI electrical Co,Ltd , Type B leakage current sensor product advantages: low cost, high precision, low temperature drift, anti-interference, small size, multiple installation methods (PCB/plug wiring/panel installation)

 

 

 

3.TypeA+DC6mA

The first method is the wall-box solution led by Tesla. The device itself does not have smooth DC leakage detection. When the European standard IEC61851 safety regulations are upgraded, there is no corresponding upgraded integrated AC/DC sensor inside the body. This means that European users must hold Type B leakage protection under the mandatory requirements of safety regulations before the construction of the charging pile can be completed for you.

 

The second method is a relatively low-cost integrated solution. Since the national energy standard has not yet been upgraded, this solution is used in export charging piles and domestic high-end car brands. It also has outstanding features. It uses the characteristics of Type B leakage current sensor (Type B-Sensor) for AC and DC detection, and cooperates with the calculation control of relays and MCU to complete the entire leakage current protection. The core is the detection and processing of Type B leakage current sensor (Type B-Sensor).

 

Charging is safer, power is more accurate, and design is more efficient.

 

 

 

 

Here are two sets of selection ideas:

 

1.Analog signal output

The advantage of real-time monitoring of leakage current is that it can retain the true state of the detected leakage to the maximum extent, and it is highly operable. A set of protection mechanisms can be customized based on the understanding of the leakage current value and protection time, which is flexible and diverse.

 

 

2.Digital signal output

The advantage of protecting leakage current is that it integrates the leakage protection requirements of IEC62752 (mode2) and IEC62955+TypeA (mode3). It does not require any calculation or processing, and protects against leakage according to high and low levels. It is plug-and-play. It saves a lot of design energy for engineers and reduces the burden on MCU resources.

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