North American 38kV Circuit Breaker

The North American 38kV circuit breaker is used in 34.5kV power systems. It is a miniaturized vacuum circuit breaker with a center mounted size and installed with rollers for rolling on the ground, making it convenient for maintenance and replacement outside the cabinet.

Compact and compact compartment, 1054mm wide, 1400mm deep, 1500mm high, highly integrated with all distribution primary and secondary circuits

North America 38kV, power frequency withstand voltage 80kV, lightning impulse withstand voltage BIL 150kV. Compared with the GB standard 40.5kV power frequency withstand voltage of 95kV and lightning impulse withstand voltage of 185kV, they are slightly lower.

The North American 38kV vacuum circuit breaker has a phase spacing of 280mm and a chassis width of 846mm. The 3000A 40kA static contact has a diameter of 72mm and a plum blossom contact outer diameter of 116mm, suitable for use on the contact box of low-voltage through type current transformers.

The reinforced propulsion chassis has two guide rods fixed on the front of the circuit breaker compartment rail, with high strength. The distance from the test position to the working propulsion of the circuit breaker is 420mm.

Double roller structure, the bottom roller is used for moving outside the cabinet, with three rollers on each side for a total of six rollers. The weight of the circuit breaker is very large, with a 3000A 40kA circuit breaker weighing up to 450kg. Therefore, the rollers must be strong enough to support the movement of the circuit breaker.

The rollers on both sides of the chassis are used to roll the circuit breaker on the guide rail inside the cabinet, that is, the working roller. The positioning of the switchgear is also based on the lower end surface of the working roller, with a distance of 588.5mm from the reference surface to the lower contact of the circuit breaker, a distance of 400mm between the upper and lower contacts, and a distance of 1186mm from the secondary plug to the working roller reference.

The overall height of the circuit breaker is 1339mm, with a depth of 900mm and a width of 862mm.

38kV North American switchgear is arranged in a single layer, generally with a compact structure and a voltage transformer handcart compartment on the upper part

Therefore, the height of the circuit breaker compartment should not be too high, usually around 1.5 meters, and secondary devices such as microcomputer protection should be installed at the front of the circuit breaker compartment. 1500-1339=161mm， Used for upper and lower partition space, while also considering the opening space of the valve.

Due to the installation of the current transformer on the primary contact box, which is fitted onto the contact box in front of the cabinet, the contact box is longer and the flip type metal valve is flipped up and down. The outer diameter of the plum blossom contact is relatively small, and to ensure a current carrying capacity of 3000A, a large contact pressure is required to reduce resistance and temperature rise. Therefore, the force required for a moving contact to engage with a stationary contact is relatively large, requiring a significant pushing force.

The width of the North American 38kV air insulated armored switchgear is 41.5 inches, 41.5 × 25.4=1054mm, 1054-890=164164/2=82. The bending width on both sides of the circuit breaker compartment is 80mm, which can meet the installation and wiring requirements of the secondary terminals on both sides of the front compartment. If the compartment width is even smaller or the circuit breaker is too wide, there will be insufficient space for the installation of secondary devices.

Circuit breakers and their compartments are the core of North American medium voltage armored switchgear, integrating secondary components such as rails, valves, current transformers, and auxiliary switches. Modular compartments can meet different switchgear designs, with a double-layer and single-layer design. Other functional handcarts such as voltage transformers, power source transformers, and fuse handcarts are separate modules that can be flexibly combined with circuit breaker compartments to form cabinets that meet the needs of power distribution systems.

The height of the 38kV voltage transformer handcart and power transformer handcart compartment is 800mm, which can be directly placed on the upper part of the circuit breaker compartment and connected to the line side or busbar side through cables. The overall height of the switchgear is 1500mm+800mm=2300mm, and the total height of the reinforced base is 2400mm.