How does RCD work in EV chargers?

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Have you ever heard about the RCD? It's an essential part of EV chargers. RCD means residual current device. A residual current device (RCD) is an electrical safety device that quickly disconnects a circuit when it detects an imbalance in the electric current, indicating a leakage or fault to the ground. This device is crucial for charging safety which every EV owner should think about. Here's how this small device makes a big impact on charging your ride safely.

RCD in EV chargers

Ground faults can be particularly dangerous in EV chargers due to the high voltage and current involved. RCDs protect against ground faults, as well as water ingress and electrical arcing.

When the RCD senses that something isn't quite right with the flow of electricity, it creates a kind of electrical signal in one of its coils, which we call the "tripping coil." This signal acts like an alarm, telling the parts of RCD that there might be a problem. In response to this alarm, the RCD instantly stops the flow of electricity to the circuit it's guarding. 

Types of RCD

There are Type A, Type AC, and Type B RCDs. They can detect different types of current. 

Type A is designed to detect AC and pulsating DC faults. It offers a higher level of protection, making it suitable for a broader range of applications, including those involving electronic or semiconductor devices. 

Type AC is the most basic type of RCD. It can only detect AC currents. Therefore, they have a sine wave symbol representation.

Type B RCD is the most advanced, detecting all types of currents. They're used in high-power applications such as EV charging systems, PV systems, etc., where a three-phase rectification is employed.