In the power system, 10/0.4kV transformers, low-voltage circuit breakers, transformers and bus mating tables are the key components to ensure the safe and stable transmission of electric energy. Each of them has different tasks, but they work closely together to form the core architecture of the power system.
The 10/0.4kV transformer is a common step-down device in the power system, which is responsible for converting high-voltage electrical energy into low-voltage electrical energy to meet daily electricity demand. The low-voltage circuit breaker is a protective equipment in the power system, which is mainly used to cut off the power supply in time when the circuit is overloaded, short circuit and other abnormal conditions, so as to prevent equipment damage and fire accidents.
The transformer is an important equipment in the power system, which is used to convert high voltage and high current into low voltage and small current in order to facilitate the normal operation of measurement and protection equipment. The bus is the backbone of the power system, which is responsible for transmitting electrical energy from the transformer to the various electrical equipment. The following editor will share with you 10/0.4kV transformer, low-voltage circuit breaker, transformer and bus matching table, recommended for everyone to collect!
Annotation:
1. Ip—peak short-circuit current, Ik—effective value of symmetrical steady-state three-phase short-circuit current, and calculation of short-circuit current is based on the infinity of the capacity of the superior system.
Calculation formula:
(1) Sec/1000(1.732U.K%)= 100C/1000(1.7320.4UK)=144.34C/1000UK(of)
(2) Ip =2.55Ik
③ 变压器高压侧额定电流=Sr/1.732Ue=Se/17.32（A）
低压侧额定电流=Sr/（1.732Ue）=Se/（1.7320.4）=1.443Se （A）
2. The grounding wire on the low-voltage side of the transformer is calculated according to the connection method of transformer D, yn11, the negative sequence and zero sequence impedance of the transformer are equal to the positive sequence impedance, the low-voltage side of the transformer is 5m, and the short-circuit removal time is 0.6s.
3. The outgoing line on the low-voltage side of the transformer selects the copper core cable, copper bus and bus duct according to the ambient temperature, and the overload coefficient is 1.25. The parallel coefficient of single-core cable is 0.8, the parallel coefficient of multi-core cable is 0.9, the temperature coefficient of YJV cable is 0.96, and the temperature correction coefficient of bus bar is 0.887.