Characteristics of electrical bus connection | electrical bus bar connection
(1) Single bus wiring. Single bus wiring has the advantages of simplicity and clarity, less equipment, small investment, convenient operation and expansion, etc., but its reliability and flexibility are poor. When the busbar or the busbar isolation switch fails or is overhauled, all the power supply of the busbar must be disconnected.
(2) Double bus wiring. Double busbar wiring has the advantages of reliable power supply, convenient maintenance, flexible scheduling or easy expansion. However, this kind of wiring uses many equipment (especially isolating switches), the power distribution device is complicated, and the economy is poor; in operation, the isolating switch is used as an operating electrical appliance, which is prone to misoperation and inconvenient to realize automation; especially when the busbar system fails , It is necessary to cut off more power sources and lines in a short time, which is not allowed for particularly important large power plants and substations.
(3) Single, double bus or bus section plus bypass. Its power supply reliability is high, the operation is flexible and convenient, but the investment has increased, and the economy is slightly worse. Especially when the bypass circuit breaker is used to carry the circuit, the operation is complicated, which increases the chance of misoperation. At the same time, the installation of bypass circuit breakers complicates the corresponding protection and automation systems.
(4) 3/2 and 4/3 wiring. It has high power supply reliability and operational flexibility. Any busbar failure or maintenance will not cause a power outage; except for the short-term power failure of the two circuits connected to the circuit breaker when the circuit breaker fails, any other circuit breaker failure or maintenance will not interrupt the power supply; even the two sets of busbars fail at the same time (or one line). In the extreme case of another group failure during group maintenance, the power can still continue to be delivered. However, this wiring uses more equipment, especially circuit breakers and current transformers, which require a large investment, and the secondary control wiring and relay protection are more complicated.
(5) Bus-transformer-generator unit wiring. It has the characteristics of simple wiring, less switchgear, simple operation, suitable for expansion, and because there is no generator outlet voltage bus, the short-circuit current of the generator and the main transformer is reduced.
Power system operation wiring mode-neutral point operation mode
It refers to the connection mode of the star-connected generator and transformer neutral point to the ground in the system. Divided into large ground current system and small ground current system.
Large ground current system: The neutral point is directly grounded or passes through a low impedance grounding system. Such as 110KV, 380V/220V.
Low ground current system: the neutral point is not grounded or the system is grounded through the arc suppression coil and other high impedance. Such as 6KV, 10KV, 35KV. In the 6~10KV power grid, the grounding point capacitance current exceeds 20~30A, and the grounding point capacitance current in the 35KV~66KV power grid exceeds 10A. An arc suppression coil must be installed. When single-phase grounding occurs, the fault current is generally small, especially after the arc suppression coil is compensated, it is about 20~30A, and the small grounding current system comes from this. my country has generally adopted compensation methods. The automatic device used to determine the grounding point and issue an alarm is a small current grounding line selector.
electrical bus bar connection