Spring rains bring not only a humid environment and depressing atmosphere, more likely to make people into worry. What is more worrying is that, due to the increase of moisture and water vapor in the air, power lines and electrical equipment are prone to short circuits and leakage in the case of moisture and water immersion, which can lead to damage to electrical equipment in light cases and can lead to equipment scrapping, casualties and other major accidents in heavy cases.
Whether in the residential, building, or industrial, infrastructure and other areas, leakage protection measures in the circuit are essential. An effective anti-leakage measure is the installation of earth leakage protection circuit breakers in each circuit loop, which will be present in each distribution box to protect the safety of electricity consumption.
Its working principle is: Once the circuit leakage, overload, short circuit and other accidents, leakage protection circuit breaker will immediately trip, break the circuit to protect the safety of personnel, lines and appliances. As shown in the figure below once touched the live fire – human body – earth – ground constitutes a circuit, so that there is a current flow through the human body electrocution accidents.
Leakage protection circuit breaker is generally a combination of two parts: miniature circuit breaker and leakage protection device. Although the combination of miniature circuit breakers and earth leakage protection devices can improve the overall safety of electricity, but the combination of the two is often larger, especially for multi-loop circuits, users in the circuit design, terminal distribution installation construction and renovation process, had to increase the volume of the distribution box, not only the overall cost will increase, but also in the design and construction process will bring more restrictions, reducing the flexibility of construction.
So, the question arises.
Different electricity scenarios, which kind of leakage protector should be used in the end?
1.It is best to ask the power supply department to participate in the design and selection when available, and to purchase products certified by electrical product certification agencies. The selected specifications should be in line with the actual load.
2. large public places, high-rise buildings for fire protection leakage protector, should be selected rated residual action current less than 500mA, the action only sound and light alarm and not automatically cut off the main power supply circuit relay-type leakage protector, several other parameters to meet the actual load of the distribution line of the corresponding specifications leakage protector.
If the equipment waveform contains DC components, in addition to considering the parameters in “2”, the selection should be dedicated to the DC component of the leakage protector.
3.the use of leakage protection in the family power supply line, is to protect personal safety, to prevent electric shock accidents as the main purpose. Therefore, the rated operating voltage should be 220V, rated operating current of 6A or 10A (installed with air conditioners, electric showers and other high-power appliances to increase one to two levels), rated residual action current (leakage current) less than 30mA, action time less than 0.1 seconds of single-phase leakage protector.
We all know that the leakage protector can protect the safety of electricity, but you know how to choose the right leakage protector? AC-type circuit breakers can easily protect the safety of electricity, and nowadays, induction cookers, microwave ovens and other electrical appliances with pulsating DC components in the current more and more, which has exceeded the protection range of AC-type leakage protector. So, with the A-type leakage protector, it is not only applicable to the home. It can also be applied in office buildings and other environments equipped with many computers. However, nowadays, many air conditioners, washing machines, heating pumps, etc. in homes and commercial buildings. All have entered the era of one-way inverter, in order to more thoroughly protect personal safety and prevent the potential risk of electric shock, there is also F-type leakage protector. It can protect the safety of electricity in most environments in life. Then the question arises, how to protect the safety of electricity in charging piles, elevators and other equipment? Industrial equipment and three-phase photovoltaic applications in the AC-DC conversion, more will need to use the B-type earth leakage protector.
AC type leakage circuit breaker: It is developed for industrial frequency sinusoidal leakage currents involved, and can reliably protect against both suddenly applied and slowly rising sinusoidal leakage currents.
Type A earth leakage circuit breaker: Type A earth leakage circuit breaker and AC earth leakage circuit breaker in the working principle (measuring leakage value through zero sequence current transformer) basically want to unify, only the magnetic characteristics of the transformer has been improved. It ensures the decoupling under the following conditions.
(a) with AC type
(b) residual pulsating DC current
(c) residual pulsating DC current superimposed on a smooth DC current of 0.006A.
Type B Earth leakage circuit breaker：Type B earth leakage circuit breaker reliably protects against sinusoidal AC signals, pulsating DC signals and smooth signals, and has higher design requirements than Type A earth leakage circuit breaker. It ensures decoupling under the following conditions.
(a) Same as Type A.
(b) To 1000Hz residual sinusoidal AC current.
(c) residual AC current superimposed ah 0.4 times the rated residual current of smooth DC current
(d) Residual pulsating DC current superimposed on 0.4 times the rated residual current or 10mA of smooth DC current (whichever is greater)
(e) Residual DC current from the following rectified lines.
— For 2-pole, 3-pole and 4-pole earth leakage circuit breakers, line to line two half-wave bridge connections.
— For 3-pole and 4-pole earth leakage circuit breakers, 3 half-wave star connections or 6 half-wave bridge connections.
Type F Earth Leakage Circuit Breaker: In addition to being able to secure a release as with Type A Earth Leakage Circuit Breaker (if applicable), in addition to securing a release at the following currents.
(a) Suddenly applied or slowly rising compound residual currents in circuits powered by phase and neutral or phase and grounded intermediate conductors.
(b) Pulsating DC residual currents superimposed on smooth DC currents.
How to wire the earth leakage switch?
The incoming and outgoing terminals of the leakage switch are marked with the letters L and N on the shell of the leakage protection switch, the letter L represents the fire line, the letter N represents the zero line; leakage protection switch wiring must be wired in accordance with the above identification, the following is to give you an analysis of the leakage protection switch above the labeling problem and the corresponding wiring method.
The first we look at 1P + N leakage protection switch labeling and wiring methods.
1P + N of the leakage protection switch terminals next to the shell above are marked, some are just marking marking one of the terminals is N, the other terminal is not marked is L; some are two terminals are marked, one marking N, the other marking L;
We take the above picture of this 1P + N leakage protection switch as an example, this leakage protection switch into the end and out of the end is only identified on the right side of the terminal for the N, the left side of the terminal are not identified, then is L;.
The above picture of this 1P + N leakage protection switch wiring method is: the inlet side of the power incoming line is connected to the left side, i.e., no identification of the terminal, the incoming power incoming line is connected to the right side of the zero line, i.e., identification of the N terminal; the outgoing load side of the wire is connected to the left side of the fire line, i.e., no identification of the terminal, the outgoing load side of the zero line The zero wire on the load side of the outlet is connected to the right side, i.e. the terminal that identifies N.
The second we look at 2P leakage protection switch labeling and wiring methods.
There are two types of 2P leakage protection switch, one is the leakage protection switch without logo, the other is the leakage protection switch with logo, no logo 2P leakage protection switch wiring is not required, left zero right fire or left fire right zero are available; 2P leakage protection switch with logo is also marked with L and N, or only N logo, representing the meaning of the leakage with 1P + N switch is the same, L represents the connection of the fire line N represents the connection of the zero line.
We take the above picture of this 2P leakage protection switch as an example to introduce its wiring method: the incoming power line in the fire wire is connected to the right side, i.e., no logo on that terminal, the incoming power line in the zero wire is connected to the left side, i.e., logo N on that terminal; the outgoing load side wire in the fire wire is connected to the right side, i.e., no logo on that terminal, the outgoing load side in the zero wire is connected to the left side, i.e., logo N on that terminal.
The third we look at the 3P leakage protection switch labeling and wiring methods.
3P leakage protection switch in accordance with whether there is a logo to divide, there are also two kinds of roughly, one is the leakage protection switch on the logo L1L2L3 and N, the other is the leakage protection switch on just the logo out N, where the L1L2L3 represents the three phases of the fire line, N represents the zero line.
We take the above picture of this 3P leakage protection switch as an example, to introduce its wiring method: the incoming power line in the three phases of the fire wire connected to the three terminals on the left side, that is, no identification of the three terminals, the incoming power line in the zero line connected to the right side, that is, the identification N of the terminal; outgoing load side of the wire in the fire wire connected to the left side, that is, no identification of the three terminals, the outgoing load side of the zero line connected to the right side, that is, the identification N of the terminal.