Devices and methods are provided, which detect a short circuit condition related to a semiconductor switch. A short circuit condition may be determined when a control signal of the switch exceeds a first reference, and a change of load current of the switch exceeds a second reference.

A device for detecting a fault in an AC supply comprising a detection circuit for detecting a fault in an AC supply to a load and providing a corresponding output. A disconnect circuit disconnects the load from the supply in response to an output from the detection circuit. The device also includes a generator of intermittent test pulses, and a test circuit coupled to the detection circuit and containing a first solid state switch. Each test pulse turns on the solid state switch for the duration of the test pulse so that a current simulating the fault flows intermittently in the test circuit and a corresponding output is provided by the detection circuit. The device further comprising means to disable the disconnect circuit in response to each test pulse.

A device for detecting a fault in an AC supply comprising a detection circuit for detecting a fault in an AC supply to a load and providing a corresponding output. A disconnect circuit disconnects the load from the supply in response to an output from the detection circuit. The device also includes a generator of intermittent test pulses, and a test circuit coupled to the detection circuit and containing a first solid state switch. Each test pulse turns on the solid state switch for the duration of the test pulse so that a current simulating the fault flows intermittently in the test circuit and a corresponding output is provided by the detection circuit. The device further comprising means to disable the disconnect circuit in response to each test pulse.

A transformer monitoring system that has one or more monitoring devices coupled to respective distribution transformers, and the monitoring devices each have a network device. The network devices monitor operational data of their respective distribution transformer and perform a monitoring device action based upon the operational data monitored. Further, the monitoring device transmits operational data and data indicative of the monitoring device action via the network device. The system also has a central computing device communicatively coupled to the one or more monitoring devices via the network devices and there is a processor resident on the central computing device that receives the operational data and the data indicative of the monitoring device action, interprets the received data, and performs an action based upon the operational data and the data indicative of the monitoring device action.

A transformer monitoring system that has one or more monitoring devices coupled to respective distribution transformers, and the monitoring devices each have a network device. The network devices monitor operational data of their respective distribution transformer and perform a monitoring device action based upon the operational data monitored. Further, the monitoring device transmits operational data and data indicative of the monitoring device action via the network device. The system also has a central computing device communicatively coupled to the one or more monitoring devices via the network devices and there is a processor resident on the central computing device that receives the operational data and the data indicative of the monitoring device action, interprets the received data, and performs an action based upon the operational data and the data indicative of the monitoring device action.

A method and apparatus for testing operability of a power converter with an existing power conversion assembly of a renewable energy system is disclosed. The method includes transferring a first pulse of energy from an existing power conversion assembly to a power filter of the power converter through first cells within a bridge circuit of the power converter. Another step includes determining a first current-voltage feedback associated with the first pulse. A next step includes transferring a second pulse of energy from the power filter to the existing power conversion assembly through second cells within the bridge circuit such that a portion of the first pulse moves back to the existing power conversion assembly. Another step includes determining a second current-voltage feedback associated with the second pulse. The first and second current-voltage feedbacks are compared with nominal tolerances of the power converter to ensure the power converter is operating properly.

A method and apparatus for testing operability of a power converter with an existing power conversion assembly of a renewable energy system is disclosed. The method includes transferring a first pulse of energy from an existing power conversion assembly to a power filter of the power converter through first cells within a bridge circuit of the power converter. Another step includes determining a first current-voltage feedback associated with the first pulse. A next step includes transferring a second pulse of energy from the power filter to the existing power conversion assembly through second cells within the bridge circuit such that a portion of the first pulse moves back to the existing power conversion assembly. Another step includes determining a second current-voltage feedback associated with the second pulse. The first and second current-voltage feedbacks are compared with nominal tolerances of the power converter to ensure the power converter is operating properly.

Disclosed herein is an apparatus for controlling an inverter. The apparatus determines the phase of an command voltage in a restart section taking into account the frequency of an input voltage to an electric motor when an input power is reduced below a rated power, the frequency of the input voltage into the electric motor at the time of restarting, a time period for generating a torque, and the phase of the input voltage to the electric motor at the time of the restarting.

A system and method to detect the loss or disruption of one or more phases of a three phase alternating current (AC) power source used in the operation of a valve actuator. The loss of one or more phases of a three phase AC power source may cause a peak in AC power output. While a peak in AC power output may not affect an operation of electronic circuitry, all three phases are often required to safely operate other hardware components, such as an AC motor that is associated with the valve actuator. Therefore, in response to detecting the loss or disruption of at least one phase of a three phase AC power source, this disclosure presents a system and method to inhibit damaging operations such as operating an AC motor associated with a valve actuator, and continuing to operate communications and diagnostic circuitry to report the condition.

A method analyzes an operating condition of a power converter. The method includes: providing a sample clock signal; determining repeatedly at least one operating parameter of a power semiconductor device of the power converter; and determining the operating condition of the power converter depending on the at least one determined operating parameter. The repetitions of the determining the at least one operating parameter are synchronous to the sample clock signal. For a given repetition of the determination of the at least one operating parameter, determining the at least one operating parameter includes measuring the at least one operating parameter or identifying a value for the at least one operating parameter from a previous repetition depending on a switching behavior of the power converter within the given repetition.