Abstract: A method of establishing current limits for each of a plurality of device couplers mounted on a trunk of an electrical circuit at distributed physical positions, in which each of said device couplers is capable of servicing one or more spurs connected thereto, and in which said trunk has a total trunk current and a known resistive component, comprising the steps of: a) establishing physical characteristics of the electrical circuit including i) an order in which said device couplers are mounted on said trunk along its length; ii) a load current each device coupler requires to service the one or more spurs connected thereto; and, iii) a voltage drop of each of said sections of trunk caused by the resistive component thereof, which is proportional to a physical length thereof and the combined load currents of each device coupler serviced by that section of trunk; b) calculating a current limit for each device coupler, which current limit is greater than said load current, according to a predetermined tolerance

Abstract: Apparatus for testing data communications on two wire combined power and data network systems for automation, comprising a control means and connection means adapted to connect said apparatus to a subject network segment, in which said control means comprises data signal output means adapted to impart a test data signal to said subject segment via said connection means, and a data signal disruption means adapted to vary one or more physical layer attributes of said test data signal which affect its functional quality and/or to vary one or more physical layer attributes of said subject segment which are capable of affecting the functional quality of data signals carried thereon.

Abstract: A method of establishing current limits for each of a plurality of device couplers mounted on a trunk of an electrical circuit at distributed physical positions, in which each of said device couplers is capable of servicing one or more spurs connected thereto, and in which said trunk has a total trunk current and a known resistive component, comprising the steps of: a) establishing physical characteristics of the electrical circuit including i) an order in which said device couplers are mounted on said trunk along its length; ii) a load current each device coupler requires to service the one or more spurs connected thereto; and, iii) a voltage drop of each of said sections of trunk caused by the resistive component thereof, which is proportional to a physical length thereof and the combined load currents of each device coupler serviced by that section of trunk; b) calculating a current limit for each device coupler, which current limit is greater than said load current, according to a predetermined tolerance

Abstract: Apparatus for testing data communications on two wire combined power and data network systems for automation, comprising a control means and connection means adapted to connect said apparatus to a subject network segment, in which said control means comprises data signal output means adapted to impart a test data signal to said subject segment via said connection means, and a data signal disruption digital output digital input attribute modifier means adapted to vary one or more physical layer attributes of said test data signal which affect its functional quality and/or to vary one or more physical layer attributes of said subject segment which are capable of affecting the functional quality of data signals carried thereon.

Abstract: An electrical circuit comprising a power supply, a load and a surge protection device adapted to protect said load and/or power supply from electrical fast transient events according to the requirements of IEC 61000-4-2 or 4 and which comprises a stress threshold, in which the electrical circuit further comprises a monitoring device adapted to monitor the current in said surge protection device and detect the breaching of said threshold by electrical fast transient events.

Abstract: A method of testing a short circuit protection system applied to a spur of an electric circuit. The short circuit protection system has a current limiting means which applies a current limit to the spur if the current thereon exceeds a trip level. The electric circuit has a power supply and an isolation means adapted to fully or partially isolate the power supply from the electric circuit if the current thereon exceeds a power supply trip level for longer than a deadband period. The method includes applying a test current demand to the short circuit protection system which has a current and duration sufficient for the spur current trip level but a current insufficient to exceed the power supply trip level and/or a duration insufficient to exceed the deadband period, and detecting if the current limiting means applies the current limit or not during the test current demand.

Abstract: An electrical circuit comprising a power supply, a load, first and second trunks disposed therebetween and control means adapted to control the electrical status of the first and second trunks, in which the control means comprises monitoring means adapted to monitor the current and/or voltage of the first and second trunks and to detect current and/or voltage events which are indicative of faults occurring thereon, and isolation means adapted to isolate the first or second trunk when the monitoring means detects a current and/or voltage event which is indicative of a fault occurring thereon, in which the first and second trunks are electrically connected and arranged in parallel such that the power supplied to the load is distributed substantially equally between them, and in which the control means comprises compensation means adapted to prevent the isolation means from isolating one of said first or second trunks when a current and/or voltage event which is indicative of a fault occurs thereon which is caus

Abstract: An electrical circuit confirming to the IEC 61158-2 standard comprising a power supply, a device as a load thereof, and monitoring means adapted to monitor one or more physical layer attributes of the electrical circuit, in which the device comprises an enclosure, device function electronics disposed therein and two terminals connecting said device function electronics to said electrical circuit, in which water detection means is disposed inside said enclosure, and comprises water detection probes and a physical layer attribute modifier mounted across said electrical circuit in parallel with said device function electronics, and in which when said water detection probes detect water said physical layer attribute modifier makes a modification to a physical layer attribute of the electrical circuit, which modification is detectable by said monitoring means.

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 electronic power conditioner circuit for use in an I EC 61 158 Fieldbus network comprising a series element, a capacitor and a resistor formed as a gyrator circuit, and a biasing circuit, in which said biasing circuit supplies a control voltage and/or current to a control terminal of the series element, and in which said biasing circuit is adapted to set said control voltage and/or current such that a voltage drop across the series element is maintained at a pre-determined level.

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 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, characterized 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: A method of testing a short circuit protection system applied to a spur of an electric circuit, in which the short circuit protection system comprises a current limiting means which applies a current limit to said spur if the current thereon exceeds a spur current trip level, in which the electric circuit comprises a power supply and an isolation means adapted to fully or partially isolate the power supply from the electric circuit if the current thereon exceeds a power supply trip level for longer than a dead-band period, in which said method comprises the following steps: i) applying a test current demand to said short circuit protection system which has a current and duration sufficient for said spur current trip level to be exceeded, but a current insufficient for said power supply trip level to be exceeded and/or a duration insufficient to exceed said deadband period, ii) detecting if the current limiting means applies said current limit or not during said test current demand.

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 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: 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 a surge protection device adapted to protect said load and/or power supply from electrical fast transient events according to the requirements of IEC 61000-4-2 or 4 and which comprises a stress threshold, in which the electrical circuit further comprises a monitoring device adapted to monitor the current in said surge protection device and detect the breaching of said threshold by electrical fast transient events.

Abstract: An electrical circuit confirming to the IEC 61158-2 standard comprising a power supply, a device as a load thereof, and monitoring means adapted to monitor one or more physical layer attributes of the electrical circuit, in which the device comprises an enclosure, device function electronics disposed therein and two terminals connecting said device function electronics to said electrical circuit, in which water detection means is disposed inside said enclosure, and comprises water detection probes and a physical layer attribute modifier mounted across said electrical circuit in parallel with said device function electronics, and in which when said water detection probes detect water said physical layer attribute modifier makes a modification to a physical layer attribute of the electrical circuit, which modification is detectable by said monitoring means.

Abstract: An electrical circuit comprising a power supply, a load, first and second trunks disposed therebetween and control means adapted to control the electrical status of the first and second trunks, in which the control means comprises monitoring means adapted to monitor the current and/or voltage of the first and second trunks and to detect current and/or voltage events which are indicative of faults occurring thereon, and isolation means adapted to isolate the first or second trunk when the monitoring means detects a current and/or voltage event which is indicative of a fault occurring thereon, in which the first and second trunks are electrically connected and arranged in parallel such that the power supplied to the load is distributed substantially equally between them, and in which the control means comprises compensation means adapted to prevent the isolation means from isolating one of said first or second trunks when a current and/or voltage event which is indicative of a fault occurs thereon which is caus

Abstract: An electrical circuit has a power supply, one or more devices and a diagnostics system. The diagnostics system includes a monitoring means adapted to monitor physical layer characteristics of the electrical circuit, a database containing circuit design data for the electrical circuit, and comparator means adapted to diagnose the status of the monitored physical layer characteristics of the electrical circuit by comparing them with the circuit design data.