A passive arc control system for a motor control center 60 includes an arc attenuating box having sides separating adjacent vertical bus bar phases 54, providing a physical barrier to arc flash energy. The box is open at its top and bottom forming a chimney 55. A shutter assembly for each box includes an insulator cap 62 on a free end of the bus bar and an independently moveable, box-shaped shutter 64 that slides along the bus bar away from the insulator cap, when a device is connected to the bus bar. The shutter has an opening 65 through which the bus bar passes when the device is connected to the bus bar and an opening 55′ aligned with the box's chimney. The arc control system provides a high degree of arc protection for personnel working around open motor control centers and is highly modular and easy to construct.

A switchgear interlock system includes a circuit breaker with clusters of connector fingers separated from each other by respective cluster shields. In a connected position, the connector fingers engage respective bus connectors of bus bars for electrical contact. When the circuit breaker is disconnected from the bus bars, independently movable shutters cover access to the bus connectors to prevent inadvertent contact with the bus connectors. Each shutter includes a pedestal with an attached movable mount and movable curtain. As the circuit breaker is moved into the connected position, the mount slides along the pedestal towards the bus connector causing the curtain to open and allow the connector fingers to engage the bus connectors. As the circuit breaker is being disconnected, a return spring causes the mount to slide along the pedestal away from the bus connectors causing the curtain to close and prevent access to the bus connectors.

A switchgear interlock system includes a circuit breaker with clusters of connector fingers separated from each other by respective cluster shields. In a connected position, the connector fingers engage respective bus connectors of bus bars for electrical contact. When the circuit breaker is disconnected from the bus bars, independently movable shutters cover access to the bus connectors to prevent inadvertent contact with the bus connectors. Each shutter includes a pedestal with an attached movable mount and movable curtain. As the circuit breaker is moved into the connected position, the mount slides along the pedestal towards the bus connector causing the curtain to open and allow the connector fingers to engage the bus connectors. As the circuit breaker is being disconnected, a return spring causes the mount to slide along the pedestal away from the bus connectors causing the curtain to close and prevent access to the bus connectors.

A system and method for connecting supply power to motor control components includes use of a motor control center subunit with moveable supply power contacts. After a motor control center subunit is secured into a motor control center compartment, the supply power contacts may be advanced to engage supply power buses. For disconnection, the supply power contacts may be retracted and isolated from the buses before physical removal of the subunit.

A system and method for connecting supply power to motor control components includes use of a motor control center subunit with moveable supply power contacts. After a motor control center subunit is secured into a motor control center compartment, the supply power contacts may be advanced to engage supply power buses. For disconnection, the supply power contacts may be retracted and isolated from the buses before physical removal of the subunit.

A medium-voltage switchgear system includes a three-phase circuit breaker having first, second and third single-phase vacuum interrupters connected between respective first, second and third single-phase inputs and first, second and third single-phase outputs. Magnetic actuators are connected to first, second and third single-phase vacuum interrupters, which are configured to receive an interrupt signal and in response, actuate the respective vacuum interrupter connected thereto into an open circuit condition. A controller circuit is connected to each of the first, second and third magnetic actuators and generates an interrupt signal in response to a detected single-phase overcurrent or fault on a single-phase circuit and interrupt that single-phase circuit on which the single-phase overcurrent or fault occurred and maintain power on the remaining two single-phase circuits over which a single-phase overcurrent or fault was not detected.

A medium-voltage switchgear system includes a three-phase circuit breaker having first, second and third single-phase vacuum interrupters connected between respective first, second and third single-phase inputs and first, second and third single-phase outputs. Magnetic actuators are connected to first, second and third single-phase vacuum interrupters, which are configured to receive an interrupt signal and in response, actuate the respective vacuum interrupter connected thereto into an open circuit condition. A controller circuit is connected to each of the first, second and third magnetic actuators and generates an interrupt signal in response to a detected single-phase overcurrent or fault on a single-phase circuit and interrupt that single-phase circuit on which the single-phase overcurrent or fault occurred and maintain power on the remaining two single-phase circuits over which a single-phase overcurrent or fault was not detected.

A switchgear system may include a switchgear frame and a truck carrying a circuit breaker and supported for linear movement on the switchgear frame. A drive mechanism may rack in the truck and the circuit breaker is in electrical connection with primary circuit contacts, and may rack out the truck and the circuit breaker is electrically disconnected from the primary circuit contacts. As the drive mechanism racks in the circuit breaker, a shutter linkage moves a shutter opened, and as the drive mechanism racks out the circuit breaker, the shutter linkage moves the shutter closed over the primary circuit contacts.

A switchgear system may include a switchgear frame and a truck carrying a circuit breaker and supported for linear movement on the switchgear frame. A drive mechanism may rack in the truck and the circuit breaker is in electrical connection with primary circuit contacts, and may rack out the truck and the circuit breaker is electrically disconnected from the primary circuit contacts. As the drive mechanism racks in the circuit breaker, a shutter linkage moves a shutter opened, and as the drive mechanism racks out the circuit breaker, the shutter linkage moves the shutter closed over the primary circuit contacts.

A medium-voltage switchgear system includes a three-phase circuit breaker having first, second and third single-phase vacuum interrupters connected between respective first, second and third single-phase inputs and first, second and third single-phase outputs. Magnetic actuators are connected to first, second and third single-phase vacuum interrupters, which are configured to receive an interrupt signal and in response, actuate the respective vacuum interrupter connected thereto into an open circuit condition. A controller circuit is connected to each of the first, second and third magnetic actuators and generates an interrupt signal in response to a detected single-phase overcurrent or fault on a single-phase circuit and interrupt that single-phase circuit on which the single-phase overcurrent or fault occurred and maintain power on the remaining two single-phase circuits over which a single-phase overcurrent or fault was not detected.