Analysis of the advantages and disadvantages of the wiring methods of 8 common electrical main wiring

The line transformer group wiring is the direct connection between the line and the transformer. It is the simplest way of wiring. The advantage of the line transformer group wiring is that there are fewer circuit breakers , the wiring is simple, the cost is saved, and the power supply load of the substation is greatly affected. It is suitable for urban center substation in normal second transport and one standby.

Second, bridge wiring

The bridge connection adopts 4 circuits, 3 circuit breakers and 6 isolating switches . It is a kind of wiring method with less circuit breakers and more investment. According to the position of the bridge circuit breaker, it can be divided into inner bridge and The two kinds of wiring of the outer bridge, because the reliability of the transformer is much larger than the line, so the inner bridge is used more frequently. If it is not affected and the normal operation of the transformer is not inspected when the circuit breaker is repaired, sometimes a set of isolation is attached outside the bridge. Switch, this becomes a quadrilateral wiring for long-term open loop operation.

Third, polygonal wiring

Polygonal wiring is to connect the circuit breaker and the isolating switch to each other, and each circuit breaker has an isolating switch on both sides. The circuit is sent out between the isolating switches. The equipment used for the polygonal wiring is less, the investment is saved, the operation flexibility and reliability are reliable. Good performance, under normal circumstances is a double connection, any circuit breaker maintenance does not affect the power transmission, because there is no bus, in the failure of any part of the connection, the impact on the operation of the grid is small, its main disadvantage is The number of loops is limited, because when there is a circuit breaker in the ring wiring, it is necessary to open the loop when it is overhauled. At this time, when the other loops fail, the two loops will be powered off, the fault power-off range is expanded, and the open loop operation time is increased. Long, the greater the disadvantage, the more the number of circuit breakers in the ring, the greater the chance of open-loop maintenance, generally only four-corner (edge) wiring and pentagon wiring, and for reliability, line and transformer Diagonal connection principle, the protection wiring of the quadrilateral is more complicated, and the primary and secondary circuit switching operations are more.

Fourth, single busbar segmentation wiring

Single busbar segmentation wiring is to divide a busbar circuit breaker into two sections. It has the advantages of simple wiring, low investment and convenient operation. The disadvantage is that some bus circuits will be cut off during busbar fault or maintenance.

Five, double busbar wiring

Double busbar wiring is to connect the working line, power line and outgoing line to two sets of (primary/secondary) busbars through a circuit breaker and two sets of isolating switches, and both sets of busbars are working lines, and each loop can be The circuit breaker is connected in parallel by the busbar.

Compared with a single busbar, it has the advantage of high reliability of power supply, and can repair the busbar in turn without interrupting the power supply. When a group of busbars fails, the circuit on the faulty busbar can be quickly switched back to another group of busbars. Power supply, in addition, has the advantages of convenient scheduling, expansion, and overhaul; its disadvantage is that a set of isolating switches is added to each circuit, so that the structure and floor space of the power distribution device and investment cost are increased accordingly; The complexity is easy to operate incorrectly when changing the operation mode, and it is not suitable for automation; especially when the bus fails, it is necessary to cut off more power and lines for a short time, which is not important for large power plants and substations. Allowed.

Six, double busbar with bypass wiring

The double busbar with bypass wiring is based on the double busbar connection. The bypass busbar is added, which is characterized by the advantages of double busbar wiring. When the circuit (main transformer) circuit breaker is overhauled, the power supply continues, but the bypass The switching operation is more complicated, which increases the chance of misoperation, complicates the protection and automation system, and has a large investment cost. Generally, in order to save the circuit breaker and equipment interval, when the outlet reaches 5 loops or more, a dedicated bypass is added. For circuit breakers, when the outlet is less than 5 circuits, the bus connection and bypass and bypass and bus connection are adopted.

Seven, double busbar section with bypass wiring

The double busbar section with bypass wiring is based on the double busbar with bypass wiring, and a segmented circuit breaker is added on the busbar. It has the advantages of double busbar bypass, but the investment cost is large, and the equipment interval is large. The general principle of using such wiring is:

1. When the total number of incoming and outgoing lines connected by the device is 12 to 16 times, a segmented circuit breaker is set on a group of bus bars;

2. When the total number of incoming and outgoing lines connected to the device is 17 or more, a segmentation breaker is set on the two sets of busbars.

Eight, 3/2 (4/3) circuit breaker wiring

3/2 (4/3) circuit breaker wiring is to send 2 (3) loops in the middle of every 3 (4) circuit breakers, generally only used for the bus main wiring of 500kV (or important 220kV) power grid, its main advantages Yes:

1. The operation and dispatching is flexible. When normal, the two busbars and all the circuit breakers operate, and the multi-channel ring-shaped power supply;

2. It is convenient to operate during maintenance. When a group of busbars is stopped, the circuit does not need to be switched, and any circuit breaker is inspected. The circuits are still in the original wiring mode and do not need to be switched;

3. The operation is reliable. Each circuit is powered by two circuit breakers. When the bus line fails, no circuit will be powered off.

The disadvantage of 3/2 (4/3) circuit breaker wiring is the use of more equipment, especially circuit breakers and current transformers, the investment cost is large, and the protection wiring is complicated.

Extended knowledge: CMC-L series soft starter typical application wiring diagram

note:

1. The figure above shows the single node control mode. The contact closes the soft start and the contact opens to stop the soft starter. However, it should be noted that this wiring LED panel starting operation is invalid. The start and stop signals of terminals 3, 4, and 5 are a passive node.

2. The PE grounding wire should be as short as possible and connected to the grounding point closest to the soft starter. The proper grounding point should be on the mounting plate next to the soft starter. The mounting plate should also be grounded. The grounding is functional instead of protection. Ground.

3. The secondary side diameter of the current transformer is not less than 2.5mm2. The selection of the X1/1, XI/2 terminal transformers must be configured according to the requirements of the accessory selection table.