The so-called leakage circuit breakers are divided into two types: namely, electronic leakage circuit breakers and pure electromagnetic leakage circuit breakers. Their basic principles are:
1. The electronic leakage circuit breaker is composed of several electronic components into an integrated circuit. When there is a leakage in the power supply, when the specified action current is reached, it outputs a signal through the electronic amplification function to drive the mechanism to break the circuit. Its disadvantages are: it requires a sufficient auxiliary power supply, the electronic components have poor anti-interference performance, large current impact is prone to cause incorrect actions, the electronic components are prone to aging, and the service life is short.
2. Electromagnetic Leakage Current Circuit Breaker: It is a mechanical-type leakage current circuit breaker made of high magnetic conductivity materials, permanent magnetic steel and other metallic materials through heat treatment, precise processing and purification assembly. When the leakage current reaches the specified action current, it will output a signal and through a mechanical electrical machine driving mechanism that has been heat treated, precisely processed and purified assembled, it will break the circuit.
Its drawbacks: The materials are expensive, the manufacturing process is complex and precise, and the manufacturing cost is high. However, it has overcome the shortcomings of the electronic type. In summary: Currently, developed countries such as Germany, the United States, and France have been researching, manufacturing, and gradually promoting the application of pure electromagnetic leakage circuit breakers since the late 1940s. However, developing countries are constrained by economic conditions and generally in the industrial and residential sectors, electronic products are mostly selected. But in the coastal developed provinces of our country, during the rural power grid renovation projects and construction projects, pure electromagnetic leakage circuit breakers have been widely used, making significant contributions to the cause of safe electricity use. Therefore, the JGJ46-2005.8.2.13 regulation issued by the Ministry of Construction of the People’s Republic of China clearly stipulates that pure electromagnetic leakage circuit breakers should be the preferred product for construction sites in our country. As is known to all, the construction site is a specific place because it is a temporary power supply system, and it cannot be matched with the power supply standards of industrial enterprises and residential areas. Large equipment and equipment have strong mobility, frequent large current startups, and many uncertain factors in electricity load. Therefore, there are higher requirements for leakage circuit breakers at construction sites. Only when these requirements are met can the electricity use at construction sites be safer and more effective.
Performance comparison between electromagnetic and electronic leakage circuit breakers:
Reliability and Security
Due to the relatively small number of electromagnetic components and nodes, the probability of failure is lower. Moreover, its performance is not affected by voltage fluctuations and it has excellent resistance to strong electromagnetic interference. Therefore, its overall performance is superior, more reliable, and safer.
2. Voltage Impact
2.1 When there is no auxiliary power cord: For the electromagnetic type leakage circuit breaker, since it does not have an electronic amplifier, its own operation does not require an auxiliary power supply. Therefore, it is not affected by voltage and can even operate when there is only one phase wire (hot wire). As long as there is leakage current flowing through it, it will act and provide protection. However, the electronic type does not work in this case. If the power cord of the electronic amplifier is broken, the amplifier will not work. If an electric shock/leakage occurs on any phase (hot) line at this time, it will not act and a dangerous accident will occur. For example: A 4P electronic leakage circuit breaker, with the amplifier power connected to the N and C phases. If the N line is disconnected/broken, while an electric shock occurs on phase A or C, the electronic leakage circuit breaker will not trip, but the electromagnetic leakage circuit breaker will trip because it does not need an auxiliary power supply. As long as there is an leakage power supply, it can act. Therefore, installing an electromagnetic leakage circuit breaker is safer.
2.2 During voltage fluctuations:
The performance of electronic leakage circuit breakers is not only affected by power outages, but also by voltage fluctuations. If the voltage is too high, it will damage other components; if the voltage is too low, the amplifier will not work. However, electromagnetic leakage circuit breakers are not affected by voltage fluctuations or strong magnetic fluctuations. As long as there is an electric current flowing, it can operate and provide protection. Therefore, installing electromagnetic leakage circuit breakers is safer for both people and equipment.
2.3 Incorrect connection of 220V and 380V
As stated in Article 2.2, for electronic leakage circuit breakers, if the rated voltage is 220V but is connected to 380V, it may damage other electronic components; while if the rated voltage is 380V but is connected to 220V, it may not work. However, for electromagnetic leakage circuit breakers, there is no significant impact because the electromagnetic unit is designed based on 380V, and the experimental resistance is designed based on 220V/380V. Even if the wiring is incorrect, it can still provide protection.
2.4 Reverse connection of power supply end and load end: For electronic leakage circuit breakers, it is essential that the power supply end and the load end should not be connected in reverse. Failure to do so may result in the product being damaged. This is because the power supply line of the amplifier is connected to the load end of the leakage circuit breaker. After the leakage circuit breaker trips, the amplifier also loses power. However, if the power supply end and the load end are connected in reverse; under normal circumstances in daily use, the problem is not significant (it is unfavorable for short-circuit arc extinction). But if in the leakage tripping situation, such as when the test button is pressed and released, the electronic switch in the amplifier – the thyristor has already conducted, and the leakage tripping coil is also conducting. Although the leakage circuit breaker has tripped, due to the reverse connection of the power supply end and the load end,
The amplifier remained connected to the power supply and was in a constantly conducting state (as they were designed to operate only for short periods of time). It soon burned out and could have caused a major accident.
These fault phenomena are particularly likely to occur in situations where temporary power lines are used, such as construction sites. Therefore, installing electromagnetic leakage circuit breakers is safer.
3. Anti-electromagnetic interference
Due to the amplifiers in electronic leakage circuit breakers, there are many electronic components which are susceptible to the impact voltage in the circuit and electromagnetic interference. Especially in construction sites, when large power equipment is turned on or off, it is prone to generate circuit impact voltage, which makes electronic leakage circuit breakers prone to malfunction, causing unstable power usage for users. In contrast, electromagnetic circuit breakers are not affected by voltage impact and strong magnetic waves, and will not generate errors, ensuring the safety of power usage.
4. Cost-effectiveness
The electromagnetic leakage circuit breaker performance is clearly superior to that of the electronic leakage circuit breaker. However, there is a high cost involved. Among them, the leakage trip unit must be manufactured with high-quality and precise materials, and undergo precise processing, such as wire cutting, precision grinding, heat treatment, polishing, screening, matching, and assembly on the purification workbench in the purification workshop. If you are not careful, even a little oil on your hands or a bit of water vapor exhaled can cause the trip unit to be scrapped, resulting in significant losses. During the overall product assembly, transformers and trip units are also screened and matched, which involves a large amount of work.
