Phase selection for traveling wave fault detection systems is disclosed herein. Intelligent electronic devices (IEDs) may be used to monitor and protect electric power delivery systems by detecting and acting upon traveling waves. A phase of the electric power delivery system may be selected based on the relative polarity of the traveling waves detected. The amplitude and/or polarity of the selected phase may be compared with the amplitudes and/or polarities of the other phases to determine a fault condition. For instance, the IED may determine a single-phase-to-ground fault based on the relative polarities and magnitudes of the detected traveling waves, send a protective action to the identified faulted phase, and/or continue to monitor the system for a continuation of the event or identification of a different event, such as a three-phase fault, using incremental quantities.

Phase selection for traveling wave fault detection systems is disclosed herein. Intelligent electronic devices (IEDs) may be used to monitor and protect electric power delivery systems by detecting and acting upon traveling waves. A phase of the electric power delivery system may be selected based on the relative polarity of the traveling waves detected. The amplitude and/or polarity of the selected phase may be compared with the amplitudes and/or polarities of the other phases to determine a fault condition. For instance, the IED may determine a single-phase-to-ground fault based on the relative polarities and magnitudes of the detected traveling waves, send a protective action to the identified faulted phase, and/or continue to monitor the system for a continuation of the event or identification of a different event, such as a three-phase fault, using incremental quantities.

A test circuit performs fault detection tests on a motor branch circuit, to detect pre-existing faults before a motor start-up to pre-empt potential damage to the motor branch circuit therefrom. The test circuit is configured to be coupled to the phase lines of a motor branch circuit at a set of test points strategically located on the phase lines. The test circuit includes test lines that are each coupled to a different one of the phase lines at one of the set of test points. The test circuit includes a test controller that, during a test mode, sequentially presents a low voltage supply to each phase line through the test line coupled thereto, to test for ground faults then sequentially couples the low voltage supply across each possible pairing of the phase lines to test for line-to-line faults. The test mode can be initiated manually or automatically.

A noise detection circuit 100 for a power supply, the noise detection circuit 100 comprising: an impedance element 110 connected to a line 104 for carrying a power supply current having a noise signal component, the noise signal comprising a common mode noise signal and a differential mode noise signal; a filter element 112 coupled to the impedance element 110 and configured to suppress the differential mode noise signal in the noise detection circuit 110; and an evaluation circuit 140 coupled to the impedance element 110 or the filter element 112 and arranged to sense the common mode noise signal and provide an output representative of the common mode noise signal.

A noise detection circuit 100 for a power supply, the noise detection circuit 100 comprising: an impedance element 110 connected to a line 104 for carrying a power supply current having a noise signal component, the noise signal comprising a common mode noise signal and a differential mode noise signal; a filter element 112 coupled to the impedance element 110 and configured to suppress the differential mode noise signal in the noise detection circuit 110; and an evaluation circuit 140 coupled to the impedance element 110 or the filter element 112 and arranged to sense the common mode noise signal and provide an output representative of the common mode noise signal.

The monitoring device is configured for monitoring a converter comprising a first and a second input terminals, two output terminals, a first filter branch connected between the input terminals, a second filter branch connected in parallel with the first branch, two switching branches connected in parallel with the second branch, each switching branch including two switching half-branches connected in series and in an intermediate point forming an output terminal.

The monitoring device comprises a detection impedance configured for being connected between the first and the second branches, and a detection module configured for comparing the voltage across the detection impedance with a predefined threshold, then for generating a detection signal as soon as said voltage is greater than said threshold.

The present document describes a method for analyzing the performance of a leg of a cable communication network which uses a network power supply as the power source therefor, the method using a switched-mode power supply device and comprising: electrically connecting an AC output of the switched-mode power supply device to an auxiliary power input of a cable network access device thereby providing an electrical connection to the leg of the cable communication network; switching the power source from the network power supply to the switched-mode power supply thereby providing an AC voltage to the leg of the cable communication network by the switched-mode power supply; performing a diagnosis of the performance of the leg of a cable communication network by controlling a characteristic of the AC voltage being provided to the leg of the cable communication network by the switched-mode power supply.

The present document describes a method for analyzing the performance of a leg of a cable communication network which uses a network power supply as the power source therefor, the method using a switched-mode power supply device and comprising: electrically connecting an AC output of the switched-mode power supply device to an auxiliary power input of a cable network access device thereby providing an electrical connection to the leg of the cable communication network; switching the power source from the network power supply to the switched-mode power supply thereby providing an AC voltage to the leg of the cable communication network by the switched-mode power supply; performing a diagnosis of the performance of the leg of a cable communication network by controlling a characteristic of the AC voltage being provided to the leg of the cable communication network by the switched-mode power supply.

The disclosure relates to a meter for monitoring usage of power provided by a power transmission system to a site. The meter comprises: a communication module to generate communications carried over the transmission system; a relay having a first position connecting power from the transmission system to the site and a second position disconnecting power; a request manager module to process messages from a head end associated with the transmission system; a meter module connected to a power feed associated with the transmission system to provide readings relating to the power used at the site; an event manager module to evaluate new events queued in a message queue received by the meter and after evaluating the new events to send a message to the head end relating to the earliest event in the message queue; a connection manager module managing the power connection to the transmission system.

The disclosure relates to a meter for monitoring usage of power provided by a power transmission system to a site. The meter comprises: a communication module to generate communications carried over the transmission system; a relay having a first position connecting power from the transmission system to the site and a second position disconnecting power; a request manager module to process messages from a head end associated with the transmission system; a meter module connected to a power feed associated with the transmission system to provide readings relating to the power used at the site; an event manager module to evaluate new events queued in a message queue received by the meter and after evaluating the new events to send a message to the head end relating to the earliest event in the message queue; a connection manager module managing the power connection to the transmission system.