Abstract: The present invention relates to an electric switch having a first contact element, an insulating element, and a second contact element. The first contact element includes a first contact surface on which the insulating element is disposed. The second contact element includes a conductive member moveable relative to the first contact element and the insulating element.

Abstract: A Low Voltage, “LV”, network automation system is provided which enables utilities to remotely identify location of LV faults on their networks, isolate these faults and re-energizing the healthy LV circuit by remote control. The hardware for this system is designed to be retrofitted into existing LV switchgears and panels which enables the network changeover to be done cost effectively and with minimum interruption to the network. The system also enables utilities to monitor load flows on the LV networks and identify circuits which are overloaded and gives control room operator options for redistribution of network load where possible.

Abstract: A switching arrangement is disclosed comprising: a control circuit; a latching relay controlled by the control circuit for connecting an AC source to an AC load; and a relief circuit in parallel with the relay and controlled by the control circuit. The relief circuit has two modes of operation: an inactive mode in which the relief circuit is non-conductive and an active mode in which the relief circuit is at least partially conductive. The relief circuit is partially conductive when spending both a time period in a conductive state and a time period in a non-conductive state during a half-cycle of the AC. The control circuit is configured to switch the relief circuit from inactive mode to active mode, and upon switching to active mode, to set the relief circuit as partially conductive for at least two half-cycles, wherein the proportion of time the relief circuit is conductive compared to non-conductive is increased for successive ones of the at least two half-cycles.

Abstract: The present invention relates to an electric switch having a first contact element, an insulating element, and a second contact element. The first contact element includes a first contact surface on which the insulating element is disposed. The second contact element includes a conductive member moveable relative to the first contact element and the insulating element.

Abstract: A switching arrangement is disclosed comprising: a control circuit; a latching relay controlled by the control circuit for connecting an AC source to an AC load; and a relief circuit in parallel with the relay and controlled by the control circuit. The relief circuit has two modes of operation: an inactive mode in which the relief circuit is non-conductive and an active mode in which the relief circuit is at least partially conductive. The relief circuit is partially conductive when spending both a time period in a conductive state and a time period in a non-conductive state during a half-cycle of the AC. The control circuit is configured to switch the relief circuit from inactive mode to active mode, and upon switching to active mode, to set the relief circuit as partially conductive for at least two half-cycles, wherein the proportion of time the relief circuit is conductive compared to non-conductive is increased for successive ones of the at least two half-cycles.

Abstract: A Low Voltage, “LV”, network automation system is provided which enables utilities to remotely identify location of LV faults on their networks, isolate these faults and re-energising the healthy LV circuit by remote control. The hardware for this system is designed to be retrofitted into existing LV switchgears and panels which enables the network changeover to be done cost effectively and with minimum interruption to the network. The system also enables utilities to monitor load flows on the LV networks and identify circuits which are overloaded and gives control room operator options for redistribution of network load where possible.

Abstract: An electronic ballast (10), for a gas discharge lamp (18), comprises a constant current source (14) and a switch (16). A transformer (60), for use in an igniter (90) for a gas discharge lamp (18, 40), comprises a core (62) which has interconnected legs (64, 66, 68), a first secondary winding (70) around a first leg (64), a second secondary winding (72) around a second leg (66), and a primary winding (74) around a third leg (66). An igniter (90) for a gas discharge lamp (18, 40) comprises a transformer (60) as described above and a drive circuit (92) for driving the primary winding (74).

Abstract: An energy storage coil comprises a core having an electrical conductor wound thereabout in a plurality of turns. The turns define a main zone and at least one first auxiliary zone extending along the core. The main zone has a first end and a second end. The turns in the main zone overlie one another. The first auxiliary zone is arranged adjacent to the first end of the main zone. The turns in the first auxiliary zone are arranged to provide the first auxiliary zone with lower parasitic capacitance from turn to turn than the main zone.

Abstract: An energy storage coil comprises a core having an electrical conductor wound thereabout in a plurality of turns. The turns define a main zone and at least one first auxiliary zone extending along the core. The main zone has a first end and a second end. The turns in the main zone overlie one another. The first auxiliary zone is arranged adjacent to the first end of the main zone. The turns in the first auxiliary zone are arranged to provide the first auxiliary zone with lower parasitic capacitance from turn to turn than the main zone.

Abstract: A high frequency SSB radio transmitter has an envelope amplitude modulator for varying the envelope of an r.f. signal source based on an error signal from envelope detectors detecting the envelope of the input and output waveform. It also has a phase modulator for varying the phase of the input waveform based on differences detected in a second amplitude modulator between the instantaneous phase of the input and output r.f. signal. A signal derived from the error signal controls the second amplitude modulator in a subsidiary feedback loop to maintain the size of the envelopes detected by the detectors the same, in order that a difference amplifier may operate effectively. Rapid discrepancies between the detected envelopes occurring within an envelope can then be corrected by the envelope amplitude modulator.

Abstract: A high frequency SSB radio transmitter has an envelope amplitude modulator for varying the envelope of an r.f. signal source based on an error signal from envelope detectors detecting the envelope of the input and output waveform. It also has a first phase modulator in a main feedback loop for varying the phase of the input waveform based on differences detected in a phase detector between the instantaneous phase of the input and output r.f. signal. To overcome the problem of spurious outputs from the phase detector resulting from the cross-over points of the SSB waveform when there are carrier breaks and other problems, a subsidiary, phase lock loop feeds a signal derived from the error signal to a second phase modulator to tend to hold the inputs to the phase detector in such a phase relationship that the output is zero. To cope with large phase shift errors between the input waveform and the output which result when the power amplifier changes frequency or temperature variations e.g.

Abstract: A linearity correction circuit for television transmission operates at intermediate frequency to introduce appropriate pre-distortion into the amplitude envelope to compensate for non-linearity in the power amplifier states. An array of parallel current sources (11), each of which is independently adjustable in response to the perceived requirement for pre-distortion over a corresponding amplitude band, to inject a current sufficient to introduce an appropriate differential voltage at the output. The circuit provides for the independent correction of each amplitude band, so that it is capable of operation under microprocessor control in real time.

Abstract: A high frequency circuit is arranged to modify a signal, such as a television broadcast signal, prior to high power amplification so as to compensate for distortions introduced by the amplifier. Separate signal paths give independent adjustment of the differential gain, differential phase and linearity of the signal by altering the characteristics of level dependent detectors.