The open-phase condition of a standby power transformer is detected by monitoring functions of the phase currents. The functions have parameters calculated based on reference currents, which constitute a fingerprint when all the phases are connected.

A method and apparatus for identifying an open phase of a circuit breaker on the basis of voltage. The method comprises: a protection apparatus measures three-phase voltages at two sides of a circuit breaker; respectively calculates a vector difference and an effective value of the voltages at two sides of the circuit breaker; when the phase voltages at two sides are both greater than 80% to 90% of a rated voltage, and the voltage vector difference at two sides of the one-phase or two-phase circuit breaker is greater than a set voltage, it is determined that the circuit breaker has an open phase; and actuates an alarming or tripping operation after a short time delay t.

A control apparatus including a first operation control circuit configured to open a direct-current switch when a power conversion apparatus is in a waiting state and a first direct-current voltage value is greater than a predetermined first threshold, a clocking circuit configured to, when the direct-current switch is opened, clock an elapsed time after the direct-current switch is opened, and a soundness determination circuit configured to calculate a first difference voltage value that is a difference between the first direct-current voltage value and a second direct-current voltage value when the power conversion apparatus is in the waiting state and the direct-current switch is opened, and the elapsed time is greater than or equal to a predetermined first time, to determine that the direct-current switch is abnormal when the first difference voltage value is less than or equal to the predetermined second threshold.

A control apparatus including a first operation control circuit configured to open a direct-current switch when a power conversion apparatus is in a waiting state and a first direct-current voltage value is greater than a predetermined first threshold, a clocking circuit configured to, when the direct-current switch is opened, clock an elapsed time after the direct-current switch is opened, and a soundness determination circuit configured to calculate a first difference voltage value that is a difference between the first direct-current voltage value and a second direct-current voltage value when the power conversion apparatus is in the waiting state and the direct-current switch is opened, and the elapsed time is greater than or equal to a predetermined first time, to determine that the direct-current switch is abnormal when the first difference voltage value is less than or equal to the predetermined second threshold.

A lamp is provided. The lamp includes at least one light emitting diode (LED) and an electronic circuit configured to provide power to the at least one LED. The lamp includes at least one flat circuit board having mounted thereto the at least one LED and the electronic circuit. The at least one flat circuit board acts as a heatsink to dissipate heat from the at least one LED and acts as a plurality of circuit paths for the electronic circuit and the at least one LED.

A power supply device includes a power supply circuit, a detection circuit, and a control circuit. The power supply circuit is configured to output a supply voltage. The detection circuit is configured to sequentially provide a first predetermined resistance and a second predetermined resistance according to a plurality of switching signals, in order to operate with an electronic device and the supply voltage to sequentially obtain a first detection voltage and a second detection voltage. The control circuit is configured to generate the switching signals, and determine a load resistance of the electronic device according to the first detection voltage and the second detection voltage. The control circuit is further configured to determine whether the load resistance is within a predetermined resistance range, and the power supply circuit is further configured to drive the electronic device if the load resistance is within the predetermined resistance range.

A power supply device includes a power supply circuit, a detection circuit, and a control circuit. The power supply circuit is configured to output a supply voltage. The detection circuit is configured to sequentially provide a first predetermined resistance and a second predetermined resistance according to a plurality of switching signals, in order to operate with an electronic device and the supply voltage to sequentially obtain a first detection voltage and a second detection voltage. The control circuit is configured to generate the switching signals, and determine a load resistance of the electronic device according to the first detection voltage and the second detection voltage. The control circuit is further configured to determine whether the load resistance is within a predetermined resistance range, and the power supply circuit is further configured to drive the electronic device if the load resistance is within the predetermined resistance range.

A system level electrostatic discharge (ESD) detection device includes a phase detection unit including at least one phase detector suitable for detecting a phase difference between a plurality of supply voltages or between a plurality of input signals; a storage unit suitable for shifting between a first and a second state, the second state indicating a phase difference detected by the phase detection unit; and an output unit suitable for outputting a system level electrostatic discharge (ESD) detection signal according to the first or second state of the storage unit.

In the field of multi-terminal electrical power network protection, a protection apparatus comprises a measurement apparatus to measure the respective terminal current (I.sub.L, I.sub.R1, I.sub.R2, I.sub.R3, I.sub.R4, I.sub.R5) flowing at each terminal (L, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5) in a multi-terminal network that includes a plurality of electrically interconnected terminals (L, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5). The protection apparatus also includes a control unit that is programmed to process the measured terminal currents (I.sub.L, I.sub.R1, I.sub.R2, I.sub.R3, I.sub.R4, I.sub.R5) to obtain first and second summed values (I.sub.POS(n), I.sub.NEG(n)). The first summed value (I.sub.POS(n)) is the sum at a given time (n) of the or each terminal current (I.sub.L, I.sub.R1, I.sub.R2, I.sub.R3, I.sub.R4, I.sub.R5) flowing in a first direction (D.sub.1) relative to a corresponding terminal (L, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5) and the second summed value (I.sub.NEG(n)) is the sum at the same given time (n) of the or each terminal current (I.sub.L, I.sub.R1, I.sub.R2, I.sub.R3, I.sub.R4, I.sub.R5) flowing in a second direction (D.sub.2) opposite the first direction (D.sub.1) relative to the corresponding terminal (L, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5). The control unit is further programmed to compare the phase of the first summed value (I.sub.POS(n)) with the phase of the second summed value (I.sub.NEG(n)) to determine whether a fault in the multi-terminal network is internal or external to the multi-terminal network and thereafter to produce an internal fault output signal upon the determination of an internal fault.

A power protection system includes a first DC power source, a first load, a first power bus connecting the first power source and the first load, and a first solid state circuit breaker circuit integrated in the first power bus. The first solid state circuit breaker circuit includes a first semiconductor switch, a first capacitor arranged between the high side voltage rail and the low side voltage rail closer to the power source or to the load than the semiconductor switch, and a first inductor located such that current generated by the first capacitor when unloading in case of a short circuit at the power source or at the load passes the first inductor. The controller is configured to measure a voltage change over the first inductor and trigger an actuation signal for the first semiconductor switch if a voltage change surpasses a predetermined threshold voltage.