The leakage circuit breaker plays an auxiliary role in the safety of theLow voltage distribution system of the power plant. It belongs to a class of important protection equipment. In the protection design of the low-voltage power distribution system of the power plant, the application of the leakage circuit breaker cannot be lack of, and the leakage is accurately selected.

The equipment type of the circuit breaker, according to the safety requirements of the power distribution system of the power plant, proposes several points of application of the leakage circuit breaker.

such as: (1) Check the electric shock energy of the leakage circuit breaker to ensure that it is within the limits of the standard, and regulate the leakage. The specification application of the circuit breaker;

(2) In the use of the leakage circuit breaker, the leakage current < the rated operating current of the leakage circuit breaker must be followed to avoid damage to the circuit and voltage in the low-voltage power distribution system of the power plant;

(3) leakage circuit breaker The operating current must be protected by a safety shield to protect the operation of the low-voltage distribution system.

leakage circuit breaker
power distribution

Three systems of power distribution

The safety of the low-voltage power distribution system of the power plant is mainly based on grounding protection. It can be divided into the following three protection modes according to the actual situation of the low-voltage power distribution system of the power plant.

The IT system protection in the grounding protection of the low-voltage power distribution system of the power plant refers to the direct selection of the IT protection method and the flexible distributed protection system. In the low-voltage power distribution system, the live area of the power port may not be grounded. Grounding protection is required for the high reactance and resistance position in the power port. IT system protection focuses on the protection of the external leakage conductive part in the grounding protection of the power distribution system. The safety of IT system protection is a key task in the construction of low-voltage power distribution systems. It is necessary to ensure the safety of the system and to ensure that the power supply and distribution system has uninterrupted power supply conditions to meet the needs of living and production.

The TT system protection in the grounding protection of the low-voltage power distribution system is applied to the electrical design of the low-voltage power distribution system. The TT grounding protection design is selected at the neutral point of the power supply to directly complete the safety protection of the low-voltage power distribution system. In the low-voltage power distribution system, many electrical equipments are involved, which increases the risk of electrical design. It adopts TT system protection, specifically leaks the conductive position and the neutral point of the power supply, implements efficient grounding protection, and maintains the safety of the low-voltage power distribution system. . In the low-voltage power distribution system, there is no power-on relationship between the N and PE of the neutral line. Therefore, when the TT system is protected, it is also necessary to pay attention to the non-energized design of the PE line, and protect the operation of the low-voltage power distribution system in an all-round way, reflecting the grounding protection. The role of TT system protection.

The TN system protection can be used both as a power supply and as a grounding protection condition in a Low voltage distribution system system of a power plant. In the safety design of the low-voltage power distribution system, the TN system protection method is adopted. It is necessary to connect the electrical equipment and the outer casing of the system to the protection line. Based on this mode, the neutrality of the Low voltage distribution system is connected. point. When the TN system is protected, the TN-C, TN-S, and TN-C-S modes can be planned according to the type of theLow voltage distribution system, and the advantages of the grounding protection can be fully utilized to break the limitation of the grounding protection. Under normal circumstances, in the low-voltage power supply and distribution system, TN-C is a three-phase four-wire grounding method, which is a relatively basic grounding protection method. TN-S is based on three-phase four-wire, increasing the PE line grounding, application In power plants with very high hazardous systems, the grounding protection and the level of safety protection of operating equipment are improved. The TN-CS system is the most common in coal mine power plants to maintain the safety of the power plant low-voltage distribution system.