Abstract: A static transfer switch assembly includes a first digital signal processor circuit associated with a preferred power source to detect a power quality event at the preferred power source, and a second digital signal processor circuit associated with an alternate power source to detect a power quality event at the alternate power source. A third digital signal processor circuit is in communication with each of the first and second digital signal processors and with a transfer switch. The third digital signal processor circuit computes and balances flux in real time based on sample voltages received from each of the preferred and alternate power sources, and controls the transfer switch to transfer the load from one of the power sources to the other power source, based on one of the first or second digital signal processor circuits detecting a power quality event.

Abstract: A system includes a current measurement unit, an overload timer, and a processing unit. The current measuring unit measures current through a power transistor, and the overload timer measures an overload time associated with the measured current. The processing unit receives a user-specified overload time setting or a user-specified overload amperage setting associated with a protection device connected in series with a load, receives a temperature measurement of a component associated with the power transistor or a measurement of overload time associated with the current, wherein the power transistor supplies the current to the load and the protection device, and selectively turns off the power transistor based on the measured temperature, the measured current through the power transistor, and the user-specified overload amperage setting or based on the measured temperature, the measured overload time, and the user-specified overload time.

Abstract: A static transfer switch assembly includes a first digital signal processor circuit associated with a preferred power source to detect a power quality event at the preferred power source, and a second digital signal processor circuit associated with an alternate power source to detect a power quality event at the alternate power source. A third digital signal processor circuit is in communication with each of the first and second digital signal processors and with a transfer switch. The third digital signal processor circuit computes and balances flux in real time based on sample voltages received from each of the preferred and alternate power sources, and controls the transfer switch to transfer the load from one of the power sources to the other power source, based on one of the first or second digital signal processor circuits detecting a power quality event.

Abstract: A switching assembly includes a first terminal and a second terminal, and a contactor connected to the first terminal, where the contactor includes a relay switch and a coil. The switching assembly further includes a first switch connected to the second terminal, and a rectifier bridge connected in series between the contactor and the first switch. The switching assembly also includes a control unit configured to selectively apply a control signal to the coil to cause the relay switch to open or close based on a voltage measured at the first terminal or based on a voltage drop measured across the rectifier bridge.

Abstract: A system includes a current measurement unit, an overload timer, and a processing unit. The current measuring unit measures current through a power transistor, and the overload timer measures an overload time associated with the measured current. The processing unit receives a user-specified overload time setting or a user-specified overload amperage setting associated with a protection device connected in series with a load, receives a temperature measurement of a component associated with the power transistor or a measurement of overload time associated with the current, wherein the power transistor supplies the current to the load and the protection device, and selectively turns off the power transistor based on the measured temperature, the measured current through the power transistor, and the user-specified overload amperage setting or based on the measured temperature, the measured overload time, and the user-specified overload time.

Abstract: A surge protective device is disclosed that may include a comparator to determine when a line voltage of a line is above a threshold. The device may include a switch to couple a clamping device to the line voltage when the comparator determines the line voltage is above a threshold, wherein the clamping device shunts current from the line. The switch may include a silicon-controlled rectifier (SCR) or a thyristor and the clamping device may include a selenium surge suppression device.

Abstract: A switching assembly includes a first terminal and a second terminal, a first switch connected to the first terminal, and a second switch connected to the second terminal. The switching assembly further includes a rectifier bridge connected between the first switch and the second switch, and a third switch connected between the first terminal and the second terminal. The switching assembly also includes a control unit that selectively opens and closes the first switch, the second switch and the third switch, and selectively turns on and off the rectifier bridge.

Abstract: A switching assembly includes a first terminal and a second terminal, a first switch connected to the first terminal, and a second switch connected to the second terminal. The switching assembly further includes a rectifier bridge connected between the first switch and the second switch, and a third switch connected between the first terminal and the second terminal. The switching assembly also includes a control unit that selectively opens and closes the first switch, the second switch and the third switch, and selectively turns on and off the rectifier bridge.

Abstract: A switching assembly includes a first terminal and a second terminal, and a contactor connected to the first terminal, where the contactor includes a relay switch and a coil. The switching assembly further includes a first switch connected to the second terminal, and a a rectifier bridge connected in series between the contactor and the first switch. The switching assembly also includes a control unit configured to selectively apply a control signal to the coil to cause the relay switch to open or close based on a voltage measured at the first terminal or based on a voltage drop measured across the rectifier bridge.

Abstract: A surge protective device is disclosed that may include a comparator to determine when a line voltage of a line is above a threshold. The device may include a switch to couple a clamping device to the line voltage when the comparator determines the line voltage is above a threshold, wherein the clamping device shunts current from the line. The switch may include a silicon-controlled rectifier (SCR) or a thyristor and the clamping device may include a selenium surge suppression device.

Abstract: A power supply apparatus includes first and second parallel-connected uninterruptible power supplies (UPSs), each including an AC/DC converter circuit and a DC/AC converter circuit having an input coupled to an output of the AC/DC converter circuit by a DC link, inputs of the AC/DC converter circuits of the first and second UPSs connected in common to an AC source and outputs of the DC/AC converter circuits of the first and second UPSs connected in common to a load. The first and second UPSs are configured to support a test mode wherein the first UPS is test loaded by transferring power from the output of the DC/AC converter circuit of the first UPS to the output of the DC/AC converter circuit of the second UPS. The first UPS may be configured to provide power to the load concurrent with test loading by the second UPS.

Abstract: A power converter apparatus, such as an uninterruptible power supply (UPS), includes an inverter having an input coupled to a first DC bus and a second DC bus and configured to generate an AC output with respect to a neutral terminal at a phase output terminal thereof. The apparatus further includes first and second neutral coupling circuits, each configured to selectively couple the first DC bus and the second DC bus to the neutral terminal, and a control circuit configured to cause interleaved operation of the neutral coupling circuits.

Abstract: In a power converter apparatus, such as an uninterruptible power supply, a phase reference signal is generated responsive to a DC voltage on a DC bus. A magnitude reference signal may be generated responsive to a phase current of an AC bus and/or the DC voltage on the DC bus. Power is transferred between the AC and DC busses responsive to the phase reference signal and the magnitude reference signal. Generation of the phase reference signal may include generating a DC voltage error signal responsive to the DC voltage on the DC bus, generating a phase offset signal responsive to the DC voltage error signal, and generating the phase reference signal responsive to the phase offset signal. Generation of the magnitude reference signal may include generating a volt-amperes reactive (VAR) error signal responsive to the phase current and generating the magnitude reference signal responsive to the VAR error signal.

Abstract: A power supply apparatus includes first and second parallel-connected uninterruptible power supplies (UPSs), each including an AC/DC converter circuit and a DC/AC converter circuit having an input coupled to an output of the AC/DC converter circuit by a DC link, inputs of the AC/DC converter circuits of the first and second UPSs connected in common to an AC source and outputs of the DC/AC converter circuits of the first and second UPSs connected in common to a load. The first and second UPSs are configured to support a test mode wherein the first UPS is test loaded by transferring power from the output of the DC/AC converter circuit of the first UPS to the output of the DC/AC converter circuit of the second UPS. The first UPS may be configured to provide power to the load concurrent with test loading by the second UPS.

Abstract: A power converter apparatus, such as an uninterruptible power supply (UPS), includes an inverter having an input coupled to a first DC bus and a second DC bus and configured to generate an AC output with respect to a neutral terminal at a phase output terminal thereof. The apparatus further includes first and second neutral coupling circuits, each configured to selectively couple the first DC bus and the second DC bus to the neutral terminal, and a control circuit configured to cause interleaved operation of the neutral coupling circuits.

Abstract: Paralleled uninterruptible power supplies (UPSs) including respective pulse-width modulation (PWM) power converter circuits coupled in common to an AC load bus have PWM cycles that are synchronized. In particular, sampling of control inputs of the PWM power converter circuits may be synchronized, such that, for example, sampling of control inputs to the PWM power converter circuits occurs at substantially the same time for each of the PWM power converter circuits. A common phase reference corresponding to an AC voltage phase for the AC load bus may be provided, and the PWM cycles of each of the power converter circuits may synchronized, e.g., phase locked, to the common phase reference. More particularly, the respective PWM cycles of the UPSs may be phase locked to phase locked sinusoidal reference signals generated at each of the UPSs. Sampling for other control functions may also be synchronized to the PWM cycles.

Abstract: A power converter apparatus, such as a double-conversion or line-interactive UPS, includes first and second DC voltage busses and a polyphase DC to AC converter circuit coupled to the first and second DC voltage busses and operative to generate a polyphase AC output. The apparatus further includes a control circuit operatively associated with the polyphase DC to AC converter circuit and configured to shift a DC voltage range of the first and second DC voltage busses with respect to a reference voltage responsive to a relationship among phase components associated with the polyphase AC output. The components may include, for example, actual phase voltages or modulation commands (e.g., count values) from which the polyphase AC output is generated. The reference voltage may be a neutral voltage, e.g., a voltage of an actual neutral of a load receiving the AC output or a synthetic neutral voltage.

Abstract: Paralleled uninterruptible power supplies (UPSs) including respective pulse-width modulation (PWM) power converter circuits coupled in common to an AC load bus have PWM cycles that are synchronized. In particular, sampling of control inputs of the PWM power converter circuits may be synchronized, such that, for example, sampling of control inputs to the PWM power converter circuits occurs at substantially the same time for each of the PWM power converter circuits. A common phase reference corresponding to an AC voltage phase for the AC load bus may be provided, and the PWM cycles of each of the power converter circuits may synchronized, e.g., phase locked, to the common phase reference. More particularly, the respective PWM cycles of the UPSs may be phase locked to phase locked sinusoidal reference signals generated at each of the UPSs. Sampling for other control functions may also be synchronized to the PWM cycles.

Abstract: A power supply apparatus, such as an on-line UPS, includes an AC/DC converter circuit having an input configured to be coupled to an AC source, a DC/AC converter circuit having an input coupled to an output of the AC/DC converter circuit by a DC link, and a bypass circuit operative to couple and decouple the output of the DC/AC converter circuit to and from the input of the AC/DC converter circuit. Power is transferred from the output of DC/AC converter circuit via the bypass circuit to conduct a test of the apparatus, such as a factory or field load test. For example, power may be circulated around a loop including the AC/DC converter circuit, the DC/AC converter circuit and the bypass circuit to conduct the test in order to test these components under load. A status of such components may be determined responsive to the test. In further embodiments, such components may be calibrated responsive to the test.

Abstract: In a power converter apparatus, such as an uniterruptible power supply, a phase reference signal is generated responsive to a DC voltage on a DC bus. A magnitude reference signal may be generated responsive to a phase current of an AC bus and/or the DC voltage on the DC bus. Power is transferred between the AC and DC busses responsive to the phase reference signal and the magnitude reference signal. Generation of the phase reference signal may include generating a DC voltage error signal responsive to the DC voltage on the DC bus, generating a phase offset signal responsive to the DC voltage error signal, and generating the phase reference signal responsive to the phase offset signal. Generation of the magnitude reference signal may include generating a volt-amperes reactive (VAR) error signal responsive to the phase current and generating the magnitude reference signal responsive to the VAR error signal.