- 14
- Oct
What are the requirements for the use of high, low voltage and neutral point bushings of distribution transformers?
The function of the distribution transformer bushing is to bow the high and low voltage leads inside the transformer to the outside of the oil tank, which not only serves as the lead to ground insulation, but also acts as a fixed lead. The transformer bushing is one of the current-carrying components of the transformer. Medium, long-term through the load current, when a short circuit occurs outside the distribution transformer, through the short circuit current. Therefore, there are the following requirements for distribution transformer bushings:
(1) Must have specified electrical strength and sufficient mechanical strength.
(2) It must have good thermal stability and be able to withstand instantaneous overheating during short circuit.
(3) Small shape, small quality, good sealing performance, strong versatility and easy maintenance.
The high, low voltage and neutral point bushings of distribution transformers are oil-paper capacitor bushings. The high-voltage bushing has a double flange structure, one flange is used to install the bushing on the top of the transformer, the second flange is used to connect with the SF6 pipeline bus, and the capacitor test tap is drawn between the two flanges. The upper part is sealed in SF6 pipe. The casing outlet is connected to the SF6 pipeline bus.
The low-voltage bushing of the distribution transformer is connected to the closed busbar on the low-voltage side, and the connection between the two is a soft connection.
The three single-phase distribution transformers are connected together through the neutral point bushing to form the neutral point of the transformer group, and the neutral point is directly grounded through the current transformer in the B-phase room.