Abstract: An electrical communications circuit comprising a power supply, a trunk section, a spur section, isolation means disposed between the trunk section and the spur section, diagnostics apparatus connected to the trunk section and a field device connected to the spur section, in which the field device is adapted to send data signals over the communications circuit, which data signals comprise one or more core functions, in which the communications circuit and/or the data signals function under one or more pre-determined normal operating parameters, in which the diagnostics apparatus is adapted to detect one or more pre-determined breaches of said normal operating parameters, in which a spur diagnostics module is connected to the spur section and is adapted to monitor electrical characteristics of the spur section, in which the spur diagnostics module comprises interference means adapted to interfere with the communications circuit and/or the data signals sent thereon such that said one or more pre-determined brea

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: 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 circuit comprising a power supply, a load, a pair of parallel positive cables between the power supply and the load, a pair of parallel negative cables between the load and the power supply, and incendive arc prevention means, comprising: monitoring means adapted to detect if the current and/or voltage in one of the pair of cables deviates from the other, and a control means adapted to fully or partially isolate the power supply from the pair of cables if the monitoring means detects that their current and/or voltage has deviated from the other, characterised in which: the electrical circuit comprises a common positive section between the power supply and the pair of positive cables, and a common negative section between the pair of negative cables and the power supply, in which a first modulation means is adapted to generate a modulated communications signal.

Abstract: A diagnostic system for a modular fieldbus board carrying a number of fieldbuses connected to a bulk power supply. A monitoring transceiver means is adapted in use to one or more of the number of fieldbuses by means of two or more common mode and/or differential mode signal injection and/or signal detection points, which points are dispersed between the bulk power supply and the fieldbus trunk. The monitoring transceiver means can detect one or more fieldbus physical layer characteristics between two of the two or more of said points.

Abstract: A diagnostic system for a modular fieldbus board carrying a number of fieldbuses connected to a bulk power supply. A monitoring transceiver means is adapted in use to one or more of the fieldbuses by means of two or more common mode and/or differential mode signal injection and/or signal detection points, which points are dispersed between the bulk power supply and the fieldbus trunk. The monitoring transceiver means can detect one or more fieldbus physical layer characteristics between two of the two or more of said points.

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: 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.