North American 38kV switchgear has a power frequency withstand voltage of 70kV and a lightning impulse withstand voltage of 170kV. Similar to the domestic KYN61 floor-standing switchgear, it is generally 1200mm wide and 2600mm deep. It does not use a grounding switch, and the current transformers are installed on the contact boxes in the circuit breaker compartments. Therefore, the rear cabinet only has connecting copper busbars, making it relatively simple.

The fully insulated busbar system typically uses epoxy resin fluidized bed insulation on the busbars, and the connections are insulated with PVC boxes to ensure full insulation. Due to the fluidized bed insulation of the busbars, the wall bushings do not require creepage distance to meet air insulation requirements. The through-type low-voltage current transformers are installed on the contact boxes, with a total of four single-winding current transformers installed on each phase. The 38kV contact boxes have internal and external equal-voltage shielding to ensure insulation withstand voltage requirements.

The North American medium-voltage switchgear standard IEEE C37.20.2 requires that auxiliary switches for the circuit breaker trolley position (TOC) and circuit breaker open/close position (MOC) be mounted on the cabinet. For 38kV, these are mounted on the base plate, with a mechanism driving the auxiliary switch position switching.

The core components of North American 38kV switchgear are concentrated at the front of the cabinet, resulting in a compact structure. Special requirements necessitate special designs to meet North American application requirements. Functional trolleys such as voltage transformers and fuses also need to be designed according to the standard. For example, the voltage transformer requires a discharge during the swing-out process, and the fuse requires load tripping before swinging in or out.

1. Circuit breaker contacts maintain grounding continuity in all positions.

2. A lever system prevents the circuit breaker from being opened or closed in any position other than the open (or test) position.

3. Secondary plug assembly—consisting of the secondary plug handle, slider assembly, secondary plug, and control wiring. The control wiring is disconnected via a female socket (secondary plug), which connects to the male plug on the circuit breaker.

4. The screw-in nut mechanism inserts and removes the circuit breaker.

5. The moving block connects to the circuit breaker for insertion and removal.

6. The slider is used with #8 to prevent movement of the closed circuit breaker. It can also be used with #12 to lock the circuit breaker in either position.

7. Indicates when the circuit breaker is in the fully engaged position. When the circuit breaker is fully engaged, a red flag rotated to the viewing position indicates that the circuit breaker is in the engaged position.

8. The slider interlock prevents the removal of the closed circuit breaker.

9. The Mechanism Operating Unit (MOC) switch is a lever-operated switching assembly on the circuit breaker mechanism. The MOC switch is activated by circuit breaker closure. It extends the lever from the bottom of the circuit breaker mechanism and presses it down on the lever of the operating mechanism on the MOC assembly. This, in turn, transmits the movement of the operating switch.

10. The cart-operated compartment (TOC) switch has nine poles. When the circuit breaker is pried into the connected position, four contacts close and five contacts open. As the circuit breaker is being pried into the connected position, the bracket on the circuit breaker pushes the TOC switch lever during the last inch of its travel. Therefore, the TOC switch can be used to electrically indicate whether the circuit breaker is in the connected position.

11. Encoding plate – see Safety Function, which restricts other sizes of circuit breakers from entering the switch cabinet compartment.

12. Selectable padlock for the circuit breaker in any position (up to three locks).

13. When the circuit breaker is in the connected position, the metal frame provides a closed barrier to the main compartment.

14. Tracks for the circuit breaker cart wheels.