Difference between electronic and Electromagnetic type RCD?

Classification of RCDs

The RCDs according to their release, can be divided into electronic type and Electromagnetic type.

what is an Electronic RCD?

Electronic RCD is an integrated circuit composed of several electronic components. 

When the power leakage occurs, the specified operating current is reached, and it outputs a signal through the electronic amplification function to push the mechanism to break a leakage circuit breaker.

what is an Electromagnetic RCD?

Electromagnetic RCD is a kind of leakage circuit breaker that is cut off by a mechanical and electrical pushing mechanism after being purified and assembled by heat treatment and precision processing.

Electromagnetic RCD is a mechanical leakage circuit breaker made of high magnetic permeability materials, permanent magnet steel and other metal materials through heat treatment, precision machining and purification. 

The difference between electronic and electromagnetic RCDs

The operating energy of electronic RCD and electromagnetic RCD is different: 

Electronic RCD:
when the ground fault occurs, the electronic RCD uses the electric energy provided by the fault residual voltage of the power supply voltage at the RCD terminal to operate. 

The electronic RCD needs an auxiliary power supply, which comes from the outlet end of the leakage circuit breaker (the side of the electrical equipment), and is related to the working voltage of the line. If the voltage is too low, a leakage current is generated in the line and reaches the switch Leakage current operating value, the switch will not operate.

Electromagnetic RCD:
When the residual voltage is too low, the energy is insufficient, and it will the electromagnetic RCD is operated by the electric energy provided by the fault current of the RCD, and the dangerous fault current can act regardless of the fault residual voltage of the power supply voltage.

Generally speaking, the electromagnetic RCD does not need auxiliary power supply, there is no circuit board component in it, and it has nothing to do with the operating voltage of the switch. As long as the leakage current generated by the circuit reaches the electromagnetic leakage current, the leakage circuit breaker will act to cut off the back power supply and protect personal safety. 

That is to say, the electronic RCD can only act when the residual voltage of the power failure is high enough. Therefore, in some cases, the electronic RCD is not as reliable as the electromagnetic RCD. Electromagnetic RCDs are mostly used in European countries, and some developed countries, such as the United States and Japan, use electronic RCDs more.

Usually, we can confirm the type of RCD through the circuit diagram on the front of the product.

Electromagnetic RCD:
An electromagnetic RCD shows on the case a differential transformer with a secondary winding, a polarized relay, a trigger, a TEST button and a resistor. The electronic model has an amplifier, which is additionally connected to the supply wires.

Electronic RCD:
You can distinguish electronic RCD from electromagnetic RCD by the presence of a triangle with the letter "A" in the circuit (amplifier). If there is a triangle, then the device is electronic type.

You can clearly see the fundamental difference in the diagram below:

Electronic type RCD circuit diagram	Electromagnetic type RCD circuit diagram

Application limitations of electronic RCD

According to IEC60364 building electrical installation specifications, the operating residual voltage of 220V voltage circuit RCD is 85V, and the 380V circuit RCD operating residual voltage is 70% of the circuit voltage. Household loop voltage), the electronic RCD may refuse to move.

At this time, if the RCD refuses to move, the consequence is that there may be electric shock damage. (The operating voltage of domestic electronic RCDs is generally lower than 50V)

What are the limitations of Electronic RCDs?

Electronic RCDs have limitations in wet locations.
The safe touch voltage is 36V, but that is limited to dry locations. 

If it is in wet or particularly humid places such as toilets, bathrooms, swimming pools, etc., the contact voltage for protection against electric shock is not 36V, but 25V or 12V, which is electronic RCD will not be able to reliably prevent electric shock.

That is to say, in a humid place, if the electrical equipment has a ground fault and the voltage is lower than 50V, if it is 30V, there is a possibility of electric shock injury and the electronic RCD may refuse to move. Therefore, electronic RCDs are more limited in wet places, and their reliability is relatively low.

Analysis of the reasons why developed countries such as Europe and the United States adopt different forms of RCD

Analysis of the reasons why developed countries such as Europe and the United States adopt different forms of RCD

Electromagnetic RCDs are mostly used in European countries, and some developed countries, such as the United States and Japan, use electronic RCDs more. 

There is a reason why different countries use different forms of RCD.

1. In European Countries
The phase voltage of the European distribution circuit adopts the nominal voltage of 220 ~ 240 V. The contact voltage Ut is about 100 V when the equipment encounters the ground fault of the casing, and the danger of electric shock is high. 

Therefore, electromagnetic RCDs are often used in Europe to ensure that the RCDs can reliably cut off the power supply, which is scientifically based.

2. In the United States and Japan
For personal safety, hand-held and mobile low-power electrical equipment with a high risk of electric shock that is difficult to get rid of with socket power supply is powered by 110-120 V. 

When the equipment touches the ground fault of the casing, its contact voltage is also very low. 

Even if the electronic RCD does not operate, the danger of electric shock is not high. 

Therefore, they use electronic RCDs more, which is also scientifically based.

Special reminder:

• The leakage protector cannot be used as the only protective measure;

• Install electromagnetic RCD as much as possible in wet places such as toilets;

• If conditions permit, please try to choose an electromagnetic RCD.

Conclusion

ETEK Electric is one of the companies specializing in the production and sales of earth leakage circuit breakers in China, we provide reliable and high-quality earth leakage products to help industries and households reduce electrical accidents. 

Welcome to contact us to know more details.