Electricity: electrical systems and devices – Safety and protection of systems and devices – Feeder protection in distribution networks
Reexamination Certificate
2002-01-15
2004-08-17
Sircus, Brian (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Feeder protection in distribution networks
C361S093200
Reexamination Certificate
active
06778369
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an electrical distribution device comprising an input for connection of an incoming electrical line, electrical protection means connected to the input and comprising electrical distribution feeders designed to supply electrical loads, said protection means comprising:
a main part comprising main breaking means connected to the input for connecting the incoming electrical line, and main control means for controlling opening and closing of the main breaking means, and
an electrical power distribution line connected to the main breaking means of the main part.
The invention also relates to an installation comprising an incoming electrical line, an electrical distribution device connected to the incoming electrical line, and distribution lines connected between the electrical distribution device and electrical apparatuses or loads. The invention also relates to an electrical protection process for an electrical distribution device.
Known electrical distribution devices generally comprise a switchboard comprising a main circuit breaker to which an incoming line is connected up-line and divisional circuit breakers or fuses are connected down-line to protect distribution lines supplying loads or current output sockets.
The divisional circuit breakers can be replaced by circuit breakers or switches comprising a remote control relay controlled on opening or closing by a central protection unit. A device of this kind is described in the documents EP 0,096,601 and DE 3,111,255.
In the document FR 2,688,951, the main circuit breaker is a solid-state electronic switch and feeders are connected via isolating relays. The main circuit breaker can also be of the current limiting type like the one that is described in the document EP 0,834,975.
In known installations these distribution devices can be cascade connected. In this case, the circuit breaker ratings are generally decreasing to achieve selectivity between the devices. Selectivity can also be improved by connecting the distribution devices or their circuit breakers by means of zone selective interlocks.
State of the art devices do not enable easy management of electrical system installation. Moreover, in distributed installations that are difficult to access, it is advantageous to have breaking devices having very high reliability and endurance.
OBJECT OF THE INVENTION
The object of the invention is to provide an electrical distribution device having improved reliability and endurance and enabling easy management of an electrical installation, an installation comprising such a device, and an electrical protection process improving reliability and electrical protection fault management.
In a device according to the invention, said protection means comprise at least one secondary part separated from the main part and comprising at least one secondary breaking device and secondary control means to command opening and closing of at least one secondary breaking device, said at least one secondary breaking device being connected to said distribution line and to at least one electrical distribution feeder, the secondary control means allowing opening of at least one secondary breaking device if a current flowing in said breaking device is lower than a preset opening current threshold.
In a preferred embodiment, the main control means comprise first detection means for detecting a main fault current and first control means commanding opening of the main breaking means during a preset first time, said first detection means detecting a main fault when a first main fault current threshold is exceeded by a signal representative of a current flowing in the main breaking means.
Advantageously, the first control means command opening of the main breaking means after a time delay having a preset second duration and subsequent to detection of a main fault.
Preferably, the maximum value of the preset first time delay is ten milliseconds (10 ms).
Preferably, the main part comprises a tie breaker connected to the input for connecting an incoming electrical line and connected in series with the main breaking means.
Advantageously, the main breaking means are breaking means with power semi-conductors.
Advantageously, the secondary control means comprise second detection means for detecting a secondary fault current flowing in at least one secondary breaking device, and second control means commanding opening of said at least one secondary breaking device if a secondary fault has been detected and if a current flowing in said breaking device is lower than the preset opening current threshold, said second detection means detecting a secondary fault when a second secondary fault threshold is exceeded by a signal representative of a current flowing in said at least one secondary breaking device.
Preferably, the second detection means for detecting a secondary fault current flowing in at least one secondary breaking device comprise means for detecting a polar fault corresponding to at least one current flowing in at least one conductor of said at least one secondary breaking device.
Preferably, the second detection means for detecting a secondary fault current flowing in at least one secondary breaking device comprise means for detecting a ground fault current flowing in at least two conductors of said at least one secondary breaking device.
Advantageously, at least one secondary breaking device is an electromagnetic relay. A secondary breaking device can comprise a breaking device with electronic power components.
In a particular embodiment, the distribution device comprises a communication line and at least one secondary part comprises secondary control means comprising communication means connected to the communication line, said communication means being able to receive closing information to close at least one secondary breaking device.
Advantageously, the distribution device comprises a central unit connected to the communication line to receive status information and to command opening and/or closing of at least one secondary breaking device.
Advantageously, the primary control means comprise communication means connected to the communication line to receive control signals.
In a particular embodiment, secondary control means send a priority signal with different characteristics from an information communication signal on the communication line to command opening of the main breaking means when an electrical fault is detected in a feeder supplied by a secondary breaking device and to command closing of the main breaking means when opening of a secondary breaking device has been commanded following a fault, the primary control means comprising means for detecting said priority signal and for commanding opening and closing of the main breaking means according to the presence of said priority signal.
Preferably, at least one secondary part is arranged in a building electrical distribution or connection box.
Advantageously, at least one secondary part is arranged in a building automation communication module, the secondary control means of said secondary part comprising electrical protection functions and communication and automatic control functions to command secondary breaking devices.
Preferably, an electrical power distribution line comprising at least two conductors, a communication line comprising at least two conductors, and an electrical earth or ground line comprising at least one conductor are arranged in a flat cable comprising at least five conductors.
An electrical installation according to the invention comprises an incoming electrical line, an electrical distribution device connected to the incoming electrical line, and distribution lines connected between the electrical distribution device and electrical apparatuses or loads, the distribution device being a distribution device as defined above and having a main part connected to the incoming electrical line and at least one secondary part connected to distribution lines.
An electrical protection process according to the invention comprise
Kitov Zeev
Parkhurst & Wendel L.L.P.
Schneider Electric Industries S.A.
Sircus Brian
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