Abstract: A Fieldbus system comprising a plurality of segments each comprising a trunk with its own primary power supply, and a shared redundancy system comprising one or more auxiliary power supplies and monitoring and control means, in which the monitoring and control means is adapted to detect failures in any part of any of the plurality of segments, in which in the event of a failure being detected by the monitoring and control means in any one of the plurality of segments, the monitoring and control means isolates the trunk in that segment from its primary power supply and connects said trunk to one of the one or more auxiliary power supplies, and in which any one of the auxiliary power supplies is connectable to any two or more of the trunks.

Abstract: An electrical installation comprising control and/or monitoring means connected to a field device by means of an electrical communications circuit, in which the communications circuit comprises a power supply, a communications device, the field device as a load thereof, and Intrinsic Safety means, in which the communications device is adapted to send and receive signals over the communications circuit to and from the field device, in which the field device is adapted to send and receive signals over the communications circuit to and from the communications device, in which the Intrinsic Safety means renders all or part of the communications circuit Intrinsically Safe, in which the field device is located in an Intrinsically Safe part of the communications circuit, characterised in which the communications circuit is adapted to carry DSL signals, and in which the communications device and the field device communicate with one another according to the DSL protocol.

Abstract: An electrical barrier for connecting a power supply to electrical equipment to be used in a potentially explosive area. The barrier includes a shunt zener diode for limiting the output voltage and a series resistance for limiting the current. In the arrangement shown, the shunt zener diode is a silicon carbide zener diode which has a higher resistance to large output current and/or operating temperature than zener diodes fabricated commercially.

Abstract: A Fieldbus system comprising a plurality of segments each comprising a trunk with its own primary power supply, and a shared redundancy system comprising one or more auxiliary power supplies and monitoring and control means, in which the monitoring and control means is adapted to detect failures in any part of any of the plurality of segments, in which in the event of a failure being detected by the monitoring and control means in any one of the plurality of segments, the monitoring and control means isolates the trunk in that segment from its primary power supply and connects said trunk to one of the one or more auxiliary power supplies, and in which any one of the auxiliary power supplies is connectable to any two or more of the trunks.

Abstract: A modular Fieldbus segment protector comprising a support means provided with trunk connection means, a trunk connection bus and a plurality of spur outlets, in which autonomous fault isolation means are removably mounted on the support means between the trunk connection bus and any one or more of the plurality of spur outlets.

Abstract: An electrical circuit comprising a power supply, a load, a first pair of parallel positive cables between the power supply and the load, a first pair of parallel negative cables between the load and the power supply, and incendive arc prevention means, in which the incendive arc prevention means comprises monitoring means adapted to monitor the first pair of positive cables and the first pair of negative cables, and to detect if the current and/or voltage in one of the first pair of positive cables deviates from the other, and if the current and/or voltage in one of the first pair of negative cables deviates from the other, and in which the incendive arc prevention means comprises a control means adapted to fully or partially isolate the power supply from the first pair of positive cables and the first pair of negative cables if the monitoring means detects that the current and/or voltage of one of the first pair of positive cables has deviated from the other, or if the current and/or voltage of one of the fi

Abstract: Data signal isolation apparatus comprising a first media converter adapted to convert outgoing electrical data signals into outgoing optical data signals, an optical data signal transmission means adapted to transmit said outgoing optical data signals, a second media converter adapted to convert said outgoing optical data signals back into outgoing electrical data signals, and an intrinsically safe power supply, in which the optical data signal transmission means comprises an electrical isolation gap, and in which the second media converter is powered by the intrinsically safe power supply.

Abstract: An electrical circuit comprising a power supply, a load and an incendive arc prevention means comprising a monitoring means and an isolation means, in which the monitoring means monitors the electrical circuit by means of a reactor means, in which if a short circuit with the potential to cause an incendive arc occurs in the electrical circuit the reaction of the reactor means is detected by the monitoring means and the isolation means fully or partially isolates the power supply from said short circuit, such that an incendive arc cannot occur, in which if an event with a current and/or voltage pattern which is characteristic of a propagating non-incendive arc occurs in the electrical circuit between the power supply and the load, the reaction of the reactor means is detected by the monitoring means, and the isolation means fully or partially isolates the power supply from said event, such that an incendive arc cannot occur.

Abstract: Invention relates to a capacitive proximity switch with an electrical bridge circuit for detecting of an electrically conducting face (15) approaching or moving away, wherein the electrically conducting face (15) is part of a capacitor (for example C1) of the bridge circuit, wherein at least one capacitor (C1, C2, C3, C4) and possibly at least one resistor (R9, R10) are disposed in the bridge branches of the bridge circuit as further reactances, and wherein the bridge is subjected to an alternating voltage as a bridge feed voltage (ubr). The proximity switch includes a flat multilayer printed circuit board (10) having at least two electrically insulating layers (13, 14), wherein an electrically conducting intermediate layer (11) as a first face of a capacitor is disposed between the two electrically insulating layers (13, 14).