Abstract: In accordance with presently disclosed embodiments, a system and method for controlling the temperature of medium-voltage power electronics assemblies (i.e., medium-voltage drives) is provided. The disclosed system generally includes a medium-voltage drive having one or more cabinets with power electronics devices disposed therein, one or more fans for circulating air through the cabinet to cool the devices, and one or more space heaters disposed in the cabinet. The drive also features temperature sensors used to measure various temperatures of the drive, a controller communicatively coupled to the sensors, and one or more variable frequency drives (VFD) for the fans. The controller may receive measurements regarding the ambient and power device temperatures and apply controls to vary the space heater power and fan speed in response to environmental changes.

Abstract: In accordance with presently disclosed embodiments, a system and method for controlling the temperature of medium-voltage power electronics assemblies (i.e., medium-voltage drives) is provided. The disclosed system generally includes a medium-voltage drive having one or more cabinets with power electronics devices disposed therein, one or more fans for circulating air through the cabinet to cool the devices, and one or more space heaters disposed in the cabinet. The drive also features temperature sensors used to measure various temperatures of the drive, a controller communicatively coupled to the sensors, and one or more variable frequency drives (VFD) for the fans. The controller may receive measurements regarding the ambient and power device temperatures and apply controls to vary the space heater power and fan speed in response to environmental changes.

Abstract: A transformer controller for a drive isolation transformer is provided. The transformer may include multiple sets of primary windings as an input, and the transformer controller may include multiple branches coupled between a power source and the transformer. Each branch may be coupled to its own primary winding on the transformer, and may include one or more components, such as an isolation switch, a fuse, contactor, or circuit breaker. One or more of the branches may include a pre-charge reactor to limit inrush or capacitor charging current occurring during startup, and may include a pre-charge contactor to remove the pre-charge reactor from the circuit when the startup process has reached a certain level (e.g., the charging or inrush current has dissipated, or a DC bus reaches a charged state).

Abstract: An 18n-pulse rectifier for AC drive systems having a separate DC bus for each output phase is provided, where n=any positive integer. The rectifier uses three separate phase rectifiers, one for each output phase of a transformer, each comprised of 2n six-pulse diode bridges connected in series or parallel. Each phase rectifier may be supplied with n unique sets of phase inputs from a transformer secondary winding. In some configurations, the n sets of inputs provided to each rectifier are separated by 60/n degrees of phase (when n is greater than 1), while the corresponding inputs to neighboring rectifiers are separated by 20/n degrees of phase. In a 36-pulse example, the phase offsets for the inputs provided to the rectifiers may be ?25° and +5° from the transformer primary winding (for the first rectifier), ?15° and +15° from the primary winding (for the second rectifier) and ?5° and +25° from the primary winding (for the third rectifier).

Abstract: A transformer controller for a drive isolation transformer is provided. The transformer may include multiple sets of primary windings as an input, and the transformer controller may include multiple branches coupled between a power source and the transformer. Each branch may be coupled to its own primary winding on the transformer, and may include one or more components, such as an isolation switch, a fuse, contactor, or circuit breaker. One or more of the branches may include a pre-charge reactor to limit inrush or capacitor charging current occurring during startup, and may include a pre-charge contactor to remove the pre-charge reactor from the circuit when the startup process has reached a certain level (e.g., the charging or inrush current has dissipated, or a DC bus reaches a charged state).

Abstract: An 18n-pulse rectifier for AC drive systems having a separate DC bus for each output phase is provided, where n=any positive integer. The rectifier uses three separate phase rectifiers, one for each output phase of a transformer, each comprised of 2n six-pulse diode bridges connected in series or parallel. Each phase rectifier may be supplied with n unique sets of phase inputs from a transformer secondary winding. In some configurations, the n sets of inputs provided to each rectifier are separated by 60/n degrees of phase (when n is greater than 1), while the corresponding inputs to neighboring rectifiers are separated by 20/n degrees of phase. In a 36-pulse example, the phase offsets for the inputs provided to the rectifiers may be ?25° and +5° from the transformer primary winding (for the first rectifier), ?15° and +15° from the primary winding (for the second rectifier) and ?5° and +25° from the primary winding (for the third rectifier).

Abstract: A fluidic cooling assembly for removing heat from electrical equipment includes operational diversity features in which multiple fluid moving devices are mounted in a single housing. The assembly may include a first fluid baffle and a second fluid baffle disposed within the housing so as to define a first and a second control compartment. A first fan and a second fan may be disposed within the first control compartment and the second control compartment, respectively. A first sensor and a second sensor may be configured to sense changes in operation of the first fluid moving device and the second fluid moving device, respectively; and a controller unit configured for receiving signals generated by the first sensor and the second sensor go as to the transmit control signals to the first fan and the second fan.

Abstract: A heat-dissipating cabinet structure may use a heat exchanger mounted at a boundary between an interior cabinet portion and an exterior portion, and heat-generating devices medium-voltage devices (such as high isolation IGBT or diode devices) may be mounted on the interior portion of the heat exchanger. The IGBT or diode devices may be electrically grounded within the cabinet such that contact with the external portion of the heat exchanger does not compromise the required clearance and creepage distances between the device's terminals and its base. Heat dissipating elements (e.g., fins, coils, etc.) may be formed at the outside portion of the heat exchanger to facilitate dissipation. A fan may be used to drive airflow over the exterior portion of the heat exchanger (and its dissipation elements), and the airflow may be directed by an airflow housing.

Abstract: A fluidic cooling assembly for removing heat from electrical equipment includes operational diversity features in which multiple fluid moving devices are mounted in a single housing. The assembly may include a first fluid baffle and a second fluid baffle disposed within the housing so as to define a first and a second control compartment. A first fan and a second fan may be disposed within the first control compartment and the second control compartment, respectively. A first sensor and a second sensor may be configured to sense changes in operation of the first fluid moving device and the second fluid moving device, respectively; and a controller unit configured for receiving signals generated by the first sensor and the second sensor go as to the transmit control signals to the first fan and the second fan.

Abstract: A motor controller includes an isolation switch having a main power supply terminal and a first bolted pressure contact and a load receptacle having a second bolted pressure contact. The motor controller also includes a drawout unit having a line terminal and a load terminal, the line terminal for engaging the first bolted pressure contact when the drawout unit is in an inserted position and the load terminal for engaging the second bolted pressure contact when the drawout unit is in the inserted position. The drawout unit rests on a drawer which is in turn supported by a pair of sliding rails. A current transformer generates a sensing signal for monitoring purposes. The components are arranged in a compact design which requires significantly less space than conventional designs.

Abstract: A bus bar stab and insulator assembly for a motor controller has a two-piece housing and a three-piece stab finger clip. The housing base has a number of partitions which define pathways for the stab fingers. The housing cover is slidably mateable with the base and has a tab for receiving a self tapping screw. The stab fingers extend from the housing for making contact with bus bars. The stab finger clip has two fingers with interlocking tabs secured together with a screw which also connects one or more connector cables to the clip. The fingers are constructed of copper alloy and do not require the use of springs.

Abstract: A bus bar stab insulator shroud cooperates with a bus bar stab housing to insulate and protect the stab fingers. The shroud includes an insulative member which has first and second side members connected by a central member which has first and second openings of a size sufficient for receiving stabs of a bus bar stab.

Abstract: A mechanical interlock is provided for a vacuum contactor assembly to insure that the second contactor cannot close after the first contactor closes. The interlock includes a support bracket, a cover plate and an interlock block which was first and second openings and is positioned between the support bracket and the cover plate. First and second ball bearings are positioned in the openings. The cover plate and interlock block are connected to the support bracket. First and second slide members each have an operating arm and a blocking arm with appropriate openings for cooperating with the ball bearings and interlock block openings. The operating arm of one slide is paired with the blocking arm of the other slide so when one operating arm moves the ball bearing it blocks the other slide from moving thereby preventing one of the vacuum contactors from operating.

Abstract: A load break switch and interlock assembly is housed in a cabinet with a door. The switch assembly is oriented 90.degree. from a normal position along the backwall of the cabinet and is located on a sidewall. The switch handle protrudes through the front of the cabinet. The handle is horizontally oriented to interfere with the door when the switch is closed thereby preventing the door from being opened. When the switch is open, the handle is vertically oriented and does not interfere with the door.

Abstract: A shutter mechanism is provided for a motor control center of the type having a backwall with a stab opening for receiving a stab connector for making electrical contact with bus bars which are behind the panel. The shutter consists of two pieces, a stationary member which has a central opening and a vertical slit opening into the central opening and a movable member which has a guide thereon and is positioned between the motor control center and the stationary member with the guide extending through the slit and vertically movable therein. The stationary member is fastened to the motor control center with the central opening overlaying the stab opening. The movable member moves from a closed position to an open position and then from the open position to the closed position under the force of gravity alone without the use of springs.

Abstract: A solenoid actuated mechanical interlock is provided for the draw-out type circuit breaker mechanism of a motor control center. The interlock is formed by the plunger of the solenoid engaging a slot in the bellcrank mechanism of the draw-out unit. Electric circuitry controls operation of the solenoid so that the plunger is controllably extended and retracted to prevent or permit operation of the bell crank under certain conditions.

Abstract: A warning feature for a high voltage controller or the like. A lamp is mounted on the controller cabinet, and connected to an interlock circuit so as to be illuminated whenever line voltage is being supplied to a contactor assembly, regardless of the open or closed status of the contactor itself.

Abstract: A motor control center of the high voltage type which includes a set of three vertically-disposed cubicles. The two lower cubicles house a pair of contactor assemblies, the lowermost contactor assembly being longer than the upper one. The cubicle enclosing the upper contactor is provided with a partition behind which is a compartment containing vertical bus bars. The lowermost cubicle extends beneath this compartment so that the bus bars drop directly down to engage a set of connectors which are also engaged by the lowermost contactor assembly.

Abstract: A contactor of the high-voltage type utilizing an arc chute and aligned magnetic pole pieces for urging an arc into the chute for quenching. A pair of rigid bus bars extend upon either side of the arc chute assembly, and are projected along the edges of the pole piece to supplement the arc displacement capability of the pole pieces, particularly at higher current values.

Abstract: An improved drawout carriage assembly for the contactor of a high voltage controller. The controller carriage is fabricated from a pair of sheet metal sides, interconnected at their lower edge by formed sheet metal cross members. The upper portions of the sides are comprised of planar sheets of insulating material. A series of insulative cross members are bolted between the opposed faces of the carriage side pieces and locate elements of the contactor mechanism.