Discussion on the setting of leakage circuit break

2022-08-01
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On the setting of leakage circuit breaker in resident distribution box in residential building abstract the quality of residential electrical design is closely related to the system design of resident distribution box. According to the relevant provisions of "Jiangsu residential design standard" (db32/), this paper expounds three setting modes of leakage circuit breaker in household distribution box, and analyzes the advantages and disadvantages of each setting mode

key words: regulate the setting of leakage circuit breaker

paragraph 4 of article 8.1.3 of Jiangsu provincial local standard Jiangsu Provincial residential design standard (db32/380 - 2000) stipulates that "except for wall mounted air conditioning power sockets, all power socket circuits shall be equipped with leakage protection devices, and if possible, leakage protection devices shall be set according to the circuits". Therefore, the author believes that there are at least three practical, feasible and standard setting methods for the leakage circuit breaker in the residential distribution box. This paper discusses the design of a residential distribution box system with a building area of about 90m2, including three bedrooms, one living room, one kitchen and one bathroom

1 the leakage circuit breaker is set on the socket circuit with leakage protection device

(1) advantages: this setting enables each household to adopt four leakage circuit breakers. Except for the wall mounted air conditioning socket, all power socket circuits are equipped with leakage protection devices, which well reflects the requirements of the specification. When a leakage fault occurs in one circuit, it will not affect the normal operation of other circuits, and it is also convenient to quickly find out the fault circuit and its cause

(2) disadvantages: as each household uses 4 leakage circuit breakers in this setting mode, the one-time investment is large, and the size of household distribution box is also large

(3) applicable object: this setting method is suitable for buildings with high requirements for residential power distribution and relatively sufficient construction funds

2 the leakage circuit breaker is set at the main incoming line of the power socket circuit with leakage protection device

(1) advantages: only one leakage circuit breaker is used in this setting. In addition to meeting the requirements of the above specifications, "except for the wall mounted air conditioning socket, all power socket circuits shall be equipped with leakage protection devices". However, instead of setting the circuit separately, a general leakage protection device is set for each circuit. This method achieves the purpose of less one-time investment and small box size of household distribution box. When the leakage circuit breaker trips in the sports ground adjacent to Oregon State University, the normal indoor lighting will not be affected, which brings convenience to troubleshooting and maintenance

(2) disadvantages: since there is a section of busbar behind the main incoming switch of the household distribution box, and there is another section of busbar at the back end of the leakage circuit breaker, it is easy to form a two-section busbar of the box, which increases the cost and difficulty of the box making, as well as the trouble of installation and maintenance

(3) applicable object: this setting method is relatively applicable, which not only saves investment, but also meets the specification requirements. It is suitable for the distribution box system of most residential buildings

3 leakage circuit breaker is set at the incoming line of household distribution box

(1) advantages: only one leakage circuit breaker is used in this setting mode, and the friction coefficient (0.29~0.38) of all semi-metallic materials is lower than that of non-metallic materials. The outgoing circuit is protected by a total leakage circuit breaker. The specification does not provide leakage protection requirements for lighting lines and wall mounted air conditioning socket lines, but it does not clearly indicate that leakage protection cannot be provided, that is, it is possible to provide leakage protection. Therefore, this setting method also meets the requirements of the specification, which avoids the defects of the above two methods

(2) disadvantages: since multiple outgoing circuits share one leakage circuit breaker, according to relevant information, the leakage current of each residential distribution circuit is about 5mA, so the total leakage current of the seven circuits is 35mA. If this setting method is still the same as the first two methods, the leakage circuit breaker has high impact strength and surface hardness within a wide temperature range, 30mA is selected, Leakage tripping may occur due to leakage current greater than 30mA during normal use of the line. Therefore, it is recommended to select leakage circuit breaker with leakage current of 50mA. In addition, this setting method also has the disadvantages that any socket or lighting circuit leaks electricity, the circuit breaker trips, the influence area is large, and the fault point is difficult to troubleshoot

(3) applicable object: this setting method is suitable for the situation where the requirements for power supply reliability are not high and the purpose is to save the construction cost as much as possible

4 conclusion

through the analysis and comparison of the above three settings of leakage circuit breakers, it can be seen that they have their own advantages and disadvantages, but they are all feasible. In engineering design, designers can selectively adopt the three setting methods according to the economic strength of the construction unit and the requirements for power reliability

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