Electricity: electrical systems and devices – Safety and protection of systems and devices – Circuit automatically reconnected only after the fault is...
Patent
1992-10-08
1995-02-14
Gaffin, Jeffrey A.
Electricity: electrical systems and devices
Safety and protection of systems and devices
Circuit automatically reconnected only after the fault is...
361 78, 361 42, 364483, H02H 320, H02H 306
Patent
active
053900669
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/FR 92/00099 filed 4 Feb. 1992 and based, in turn, upon French application 91 01634 of 8 Feb. 1991 under the international Convention.
FIELD OF THE INVENTION
The present invention relates to a protection device for electrical appliances, machines and installations and, more particularly, to a device protecting electrical lines (termed "user" electrical lines), connected to electrical supply lines or the supply network.
In particular, the present invention applies to the safety of complete electrical installations in dwellings, to the protection of electronic or computer systems against excessive volt ages, and to the safety of the operators of electrical machines or appliances in industry or in any other field of activity.
BACKGROUND OF THE INVENTION
The devices known hitherto, of the circuit breaker or fuse type, do not allow electrical lines to be cut quickly enough to avoid electrocution or component deterioration. Moreover, their reaction time is too long to provide good protection in the case of a storm for example. Also, these systems protect only certain electrical lines but not the neutral or the ground line.
Other known devices measure a residual current with respect to the ground connection. For that reason, these devices are sensitive to parasites and their triggering threshold has to be high.
Moreover, all the devices quoted above do not reconnect the lines after they are triggered, which can be prejudicial to the operation of alarms, refrigerators, freezers and aquaria during long absences of the user or of the proprietor.
SUMMARY OF THE INVENTION
The present invention remedy these drawbacks by connecting together all the lines to be protected so as to create a potential line with a defined and constant value during the normal operation of the installation to be protected, detecting a variation in this potential with respect to the neutral, and automatically and rapidly cutting off and by the automatic and rapid cut-off of the supply to the lines to be protected as soon as a variation of the latter potential is detected.
The device which is the subject of the present invention is therefore a protection device for electrical appliances, machines and installations comprising user electrical lines to be protected, linked to electrical supply lines, and comprising in combination: at least one resistor bridge linking the user electrical lines and creating at one of its points a defined potential, which is fixed in the course of normal operation of the installation; isolation means linked to this point for amplifying the potential difference between this point and a ground or neutral line; a threshold circuit linked to the output of this isolation means; a processor connected to the output of this threshold circuit; and a means for connecting and disconnecting the supply lines with respect to the user electrical lines to be protected, the means being controlled by said processor in such a way that an abnormal voltage variation on one of the electrical lines gives rise to a variation in the potential at the abovementioned point, this variation being detected by the threshold circuit which transmits it to the processor, which then brings about the disconnection of the supply lines from the user electrical lines.
The operation of the device can be controlled by a digital circuit adding supplementary functions, and the triggering threshold may be adjustable.
According to one variant of the device of the invention, protection can be effected partially on some parts of an electrical installation. Moreover, the return of the installation to operation, by reconnection of the cut-off lines with the supplies, may be controlled by the device within a variable, stored time scale according to the number of line cut-offs already effected.
More generally, all the functions, such as thresholds and time delays may be programmed by the user.
One of the advantages of the device according to the present invention resides in tha
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patent: 4054832 (1977-10-01), Reynolds et al.
patent: 4205358 (1980-05-01), Washington
patent: 4364007 (1982-12-01), Cutler et al.
patent: 4728885 (1988-03-01), DeSanto
patent: 5003486 (1991-03-01), Hendel et al.
patent: 5132610 (1992-07-01), Ying-Chang
World Intellectual Property Organization-WO 86/02786 Publication Date: 9 May 1986.
Parrier Henri
Parrier Jean
Dubno Herbert
Gaffin Jeffrey A.
Leja Ronald W.
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