Unlike domestic medium-voltage circuit breakers, which generally use solid-sealed poles, North American medium-voltage circuit breakers mostly employ an open structure. This design is simpler, easier to inspect and maintain, provides better ventilation and heat dissipation, and reduces the amount of copper busbars used in high-current applications.

The primary contacts of North American circuit breaker trolleys, whether tin-plated or silver-plated, have a maximum temperature rise of 65K, 10K lower than the IEC standard. The same applies to the busbar temperature rise; the temperature rise at busbar joints, regardless of whether tin-plated or silver-plated, is 65K. Therefore, heat dissipation is crucial for circuit breakers, requiring an increase in heat dissipation area to minimize self-heating.

North American vacuum circuit breakers require the circuit breaker trolley to have wheels for easy movement on the ground and maintenance. Therefore, the wheels are relatively large. For chassis-based trolleys, the outer wheel diameter can be increased, while the guide rail wheel diameter remains unchanged.

The primary contact diameter of the circuit breaker trolley is relatively small because the current transformer in North American switchgear is fitted onto the primary contact box, thus compressing the internal diameter of the contact box. Larger L-shaped contacts, such as high-current 109mm L-shaped contacts, are difficult to insert into the contact box. Therefore, smaller, higher-current-carrying bundled primary contacts are required.

There are several types of propulsion mechanisms. One type uses a screw and nut mechanism on the circuit breaker compartment floor to switch the circuit breaker trolley between the test and working positions. Another type uses two side crank arms, whose rotation drives the circuit breaker trolley's position change.

Since no grounding switch is used, the grounding contact at the bottom of the circuit breaker trolley needs to withstand short-time and peak withstand currents, such as 31.5kA RMS for 2 seconds and 82kA peak withstand current.

Circuit breaker trolleys require adapters compatible with the cabinet compartments. Only trolleys matching the compartment specifications can be moved into the compartment; trolleys of other specifications cannot. This is because North American switchgear, regardless of rated current or short-circuit current, uses the same dimensions—the circuit breaker compartment size is identical, only the contacts differ. Therefore, this design is standardized; from the initial design stage, all specifications of circuit breaker trolleys are considered, and stop specifications are defined. Assembly according to this standard during production prevents errors.

The circuit breaker trolley position also requires mechanical indicators, which can be installed on the trolley or on the compartment to indicate the trolley's position within the compartment.

POWELL 15kV (power frequency withstand voltage 36kV, lightning impulse withstand voltage 95kV) vacuum circuit breakers, whether 1200A or 3000A, have a phase spacing of 254mm, and the switchgear width is also the same: 36 inches (914mm).

ABB North American ANSI standard 38kV solid-insulated vacuum circuit breaker, rated power frequency withstand voltage 70kV, rated lightning impulse withstand voltage 170kV, switchgear width 1000mm. Due to the relatively low 1200A current, the solid-insulated poles allow for reduced phase-to-phase spacing, resulting in a more compact design.

Similarly, current transformers are mounted on the primary contact box, with four low-voltage through-core current transformers per phase. The primary contacts of the circuit breaker trolley require small-diameter products. Large casters facilitate ground movement of the circuit breaker trolley.

15kV compact vacuum circuit breaker, using GPO-3 for insulation support and phase-to-phase insulation partitions. Used in narrow switchgear, typically 26 inches (660mm), with a typical current of 1200A. Vertically arranged, with integrated contact and contact arm structure, reducing dynamic connections.