AU2016361996A1

AU2016361996A1 - B or B+ differential protection device comprising two parallel concurrent modules

Info

Publication number: AU2016361996A1
Application number: AU2016361996A
Authority: AU
Inventors: Hichem Chetouani
Original assignee: Hager Electro SAS
Current assignee: Hager Electro SAS
Priority date: 2015-12-03
Filing date: 2016-12-01
Publication date: 2018-05-17
Anticipated expiration: 2036-12-01
Also published as: FR3044836A1; EP3300542A1; EP3300542B1; WO2017093670A1; CN108292838B; AU2016361996B2; FR3044836B1; CN108292838A

Abstract

The present invention relates to a B or B+ differential protection device for detecting leakage or fault current in an electrical system supplied by at least two phase conductors of a network or by at least one phase conductor of a network and by one neutral conductor of said network. Said device (1) includes two separate detection and control modules (3 and 3'), each of which is functionally active or operational across a predetermined frequency range specific thereto. The invention is characterized in that the two modules (3 and 3') are independent of one another and are arranged so as to form two parallel and mutually independent detection channels that control the same actuator, relay or analog means (5) and in that each module (3, 3') is connected to its own specific means (6, 6') for delivering a fault signal, the frequency domains of operation of the two aforementioned modules (3 and 3') partially overlapping.

Description

The present invention relates to a B or B+ differential protection device for detecting leakage or fault current in an electrical system supplied by at least ι two phase conductors of a network or by at least one phase conductor of a network and by one neutral conductor of said network. Said device (1) includes two separate detection and control modules (3 and 3'), each of which is functionally active or operational across a ** | predetermined frequency range specific thereto. The inJ vention is characterized in that the two modules (3 and * 3') are independent of one another and are arranged so as to form two parallel and mutually independent detection ⁵ channels that control the same actuator, relay or analog means (5) and in that each module (3, 3') is connected to its own specific means (6, 6') for delivering a fault signal, the frequency domains of operation of the two aforementioned modules (3 and 3') partially overlapping.

(57) Abrege : La presente invention a pour objet un dispositif de protection differentielle de type B ou B+ permettant la [Suite sur la page suivante] wo 2017/093670 Al lllllllllllllllllllllllllllllllllllll^ detection de courant de fliite ou de defaut dans une installation electrique alimentee par au moins deux conducteur de phase d'un reseau ou par au moins un conducteur de phase d'un reseau et par un conducteur de neutre dudit reseau. Ce dispositif (1) comprend deux modules de detection et de commaude distincts (3 et 3') dont chacun est fonctionnellement actif ou operationnel sur une plage de frequences determinee qui lui est propre, et est caracterise en ce que les deux modules (3 et 3') sont independants entre eux et arranges de maniere a constituer deux voies de detection, paralleles et mutuellement independautes, commandant le meme actionneur, relais ou moyen analogue (5) et en ce que chaque module (3, 3') est relie a un moyen propre et specifique (6, 6') de delivrance d'un signal de defaut, les domaines frequentiels de fonctionnement operationnel des deux modules (3 et 3') precites etant partiellement chevauchants.

B or Β+ differential protection device comprising two parallel concurrent modules

The present invention relates to equipment and systems for the safety of goods and persons in the electrical field, more particularly the devices for protecting persons with residual current (or RCD), and relates to a differential protection device of the type B or B+ comprising two independent detection modules operating in mutual competition.

Differential protection devices are commonly integrated into domestic or tertiary electrical installations, upstream or at the entrance of the various trees of the power supply circuits in place, or closer to the receivers to which they are respectively assigned.

Typically, these electrical installations are powered by an alternating electric network, and protection devices of the aforementioned type are intended primarily to ensure the safety of people by detecting as rapidly as possible any possible leak to earth in one of the circuits or receivers to be protected. Such leaks are caused for example by direct contacts of subjects with a non-insulated conductor or indirect contacts due to mass defects. These electrical incidents are likely to generate accidents, sometimes fatal, damage to equipment (s), fire starts, localised or generalised malfunctions or the like.

Differential protection in the abovementioned context is effected in most cases in a fairly standardised manner.

For the detection of the alternative fault currents, the conductors of the circuit to be protected, or the conductors of the network or of the supply line of this circuit, pass into a toroid of ferromagnetic material of a transformer whose aforementioned conductors form the primary and which has one or more windings(s) or secondary winding(s). The toroid plays the role of a magnetic flux concentrator. Thus, in the event of a leak, resulting in an imbalance of the input and output currents in the conductors of the lines to be protected, the flux created in the toroid by this imbalance at the primary level induces a voltage in the secondary winding constituting a fault signal.

For the detection of direct or DC fault currents , it is for example known to excitate to saturation a soft magnetic toroid, crossed by the conductors of the line or network, by an alternating current. When a DC fault current occurs in the conductors, the symmetry of the saturation (positive direction/ negative direction) is broken, the resulting temporary dissymmetry being proportional to the fault current. This so-called Fluxgate method can then be used to directly exploit the fault signal, or its frequency spectrum.

Another detection principle, developed and implemented by the applicant, consists in using a voltage transformer (for example a toroid) provided with a primary (excitation coil) applying a fixed voltage and a secondary (measuring coil) having a variable transformation ratio, the value of the latter depending on the intensity of the fault current flowing through the toroid and resulting from the algebraic sum of the incoming and outgoing currents.

In the two aforementioned types of detection of fault currents (alternating and direct), the fault signal is used to control directly, or through dedicated electronics (signal processing stages), an actuator or the like (for example of the relay type). The latter in turn controls an associated trigger, a breaking or an opening mechanism, or those of other protective devices of the installation.

Instead of the aforementioned toroid, it can also be provided, in agreement with other known variants of the state of the art, to implement other types of sensors or detectors capable and intended to generate a fault signal when a differential fault occurs at the monitored network or installation.

These apparatuses or devices for differential protection may have variable characteristics. Thus, they are differentiable and characterized by their own sensitivity, which depends in particular on the type of electrical installation in which they are utilised and that they are intended to protect. Moreover, some of these devices are only capable of detecting leaks for alternating currents (AC type) or for direct currents, while others, which are more complete, offer solutions that are also applicable to pulsed direct current (types A and F) and smoothed (type B).

Moreover, for the devices having the capacity to detect alternating fault currents, the upper detection limit frequency constitutes another criterion of distinction between the different types: frequencies up to a few tens of Hz: AC; frequencies up to 1kHz: type F; frequencies up to 2kHz: type B; frequencies up to 20kHz: type B+.

Type B+ is, in relation to other types, specifically sensitive to frequencies of current fault or leakage conducive to fire outbreak, in addition to the functionality associated with type B.

Sophisticated devices of type B and B+ are currently based on complex circuit construction, which generally depend on the power supply of the network for their operation, with the provision of at least one functional sub-assembly that is not dependent on this power supply to comply to certain primary safety measures and to regulations currently in force (see for example: DIN VDE 0664-400-version 2012).

A construction solution of a type B device is for example known from the French patent application No. 2 993 058 in the name of the applicant.

To reduce the constructive complexity of these sophisticated and versatile devices, while meeting the regulatory requirements, it has been proposed to realise them in the form of modular functional arrangement.

Thus, a first known solution of this type consists in providing a device comprising a first functional module performing a measurement / detection function of type B and a second functional module performing a measurement / detection function of type A / AC. The first module is active in the presence of a network power supply and the second module becomes active only in the absence of mains power supply, the switchover between the two channels being realised using a monostable relay located at the input of the two channels and whose default position (in the absence of mains supply) corresponds to a transmission of the signal to the second module.

A second known solution consists in associating with a module performing measurement / detection type A / AC, upstream of the latter, an active electronic stage (powered by the network) which performs a correction of the bandwidth and thus allows to result in a measurement / detection of type B in the presence of a mains supply. In the absence of such a power supply, the active electronic stage is short-circuited (for example by means of a selector relay powered by the network and whose default position corresponds to the derivation of the signal relative to the electronic circuit), and the device then has a A / AC type operation.

Thus, these two known solutions aiming to simplify the type B differential protection devices are not satisfactory given the operating limitations indicated above. Moreover, neither of these two known solutions relates to a device of the type B+.

The present invention aims to overcome at least the main limitations mentioned above.

For this purpose, it relates to a type B or B+ differential protection device for detecting leakage or fault current in an electrical installation powered by at least two phase conductors of a network or by at least one conductor phase of a network and by a neutral conductor of said network, said device comprising two separate detection and control modules each comprising at least one signal processing stage adapted and intended, on the one hand, to exploit a fault signal generated by the appearance of a differential fault at said network and, on the other hand, controlling an electromagnetic actuator, relay, or other breaking or opening means of the device when said fault signal exceeds a frequency-dependent predetermined threshold value, each of said detection and control modules being functionally active or operational over a specific frequency range of its own, characterized in that the two modules are independent of each other and arranged so as to constitute two parallel and mutually independent detection channels, controlling the same actuator, relay or similar means, in that each module is connected to its own and specific means for delivering a fault signal, in that the first of the two modules is a detection and control module that is functionally active or operational for frequencies of the fault signal from 0Hz to a few tens of Hz, this first module being supplied by the network, and in that the second of the two modules is a detection and control module which is functionally active or operational for frequencies of the fault signal from a few tens of Hz to at least 1 kHz, this second module being autonomous in terms of power supply, and in particular not depending on the voltage of the network or of the sector, the frequency domains of functional operation of the two aforementioned modules being partially overlapping.

The invention will be better understood, with the aid of the following description, which relates to a preferred embodiment, given by way of non-limiting example, and explained with reference to the attached schematic drawings, in which:

Figure 1 is a schematic representation, functional and synoptic, of a differential protection device according to one embodiment of the invention;

FIG. 2 represents the evolution curves of the tripping thresholds (in mA) as a function of the frequency, of each of the two detection and control modules forming part of the device according to the invention, in agreement with the embodiment shown. FIG. 1, and

FIG. 3 represents the evolution curve of the tripping threshold (in mA) as a function of the frequency of the overall device according to the invention, represented in FIG. 1 and combining the two modules.

The latter figure schematically shows the constitution of a differential protection device 1 of type B or B+ allowing detection of leakage or fault current in an electrical installation powered by at least two phase conductors 2 of a network or by at least one phase conductor of a network and a neutral conductor 2' of said network.

This device 1 comprises two separate detection and control modules 3 and 3' each comprising at least one signal processing stage 4, 4' adapted and intended, on the one hand, to exploit a fault signal generated by the appearance a differential fault at said network and, on the other hand, to control an electromagnetic actuator, relay or similar breaking or opening means 5 of the device 1 when said fault signal exceeds a predetermined threshold value depending on the frequency, each of said detection and control modules 3, 3' being functionally active or operational over a defined frequency range of its own.

According to the invention, provision is made for:

that the two modules 3 and 3' are independent of each other and arranged so as to constitute two detection channels, parallel and mutually independent, controlling the same actuator, relay or similar means 5, each module 3, 3' is connected to its own and specific means 6, 6 for delivering a fault signal, that a first 3 of the two modules 3, 3' is a detection and control module which is functionally active or operational for frequencies of the fault signal from 0Hz to a few tens of Hz, this first module 3 being supplied by the network, and that the second 3' of the two modules 3, 3' is a detection and control module which is functionally active or operational for frequencies of the fault signal of a few tens of Hz to at least 1 kHz, this second module 3' being autonomous in terms of power supply, and in particular not depending on the voltage of the network or the sector, the frequency domains of operational functioning of the two aforementioned modules 3 and 3' being partially overlapping.

In accordance with an important characteristic of the invention, the two modules 3 and 3' each have a significant operation with respect to the other module 3', 3 on mutually complementary parts of the total frequency domain of the fault currents covered by said device 1.

Thus, due to a particular modular combination of two functional blocks 3 and 3' complementary in terms of frequency coverage, which are both permanently active in terms of detection and permanent competition for the control of the breaking or opening means 5, the invention proposes a device 1 sophisticated and optimal in terms of protection (level B or B+) while implementing modules 3 and 3' whose level of complexity, and therefore the cost, is significantly lower.

In addition, the parallel arrangement of the two modules 3 and 3' allows direct access of each of them to the conductors 2, 2' to be monitored and therefore a clean detection, and a treatment and exploitation of the results of the independent detection.

Finally, in case of power failure, the second module 3', which is not dependent on the sector or network, continues to fully ensure its protection function.

According to a characteristic of the invention, as shown in FIG. 1, the first detection and control module 3, depending on the mains voltage, is a sensitive differential protection module and which reacts to smoothed direct fault currents, at lowfrequency and I or provided with a large DC offset, for example a fault current resulting from three phases as described in paragraph 9.2.16 of the IEC 62423 Standard.

According to another characteristic of the invention, also apparent from FIG. 1, the second detection and control module 3' is a type F differential protection module, possibly incorporating a fire-break function (therefore of the F+ type), the operation of said second module 3', including the realisation of the aforementioned function, being independent of the voltage of the network or of the sector.

As already indicated above, several types of sensors can be implemented in relation to each of the two modules 3 and 3' to provide the latter with fault signals when a differential fault occurs at the level of the monitored installation.

However, in accordance with a preferred practical variant, each of the own means 6 and 6' for delivering a fault signal consists of a toroid 7, 7' of ferromagnetic material comprising, on the one hand, a primary winding formed by one of the conductors 2, 2' of the monitored network or by an excitation winding 10, according to the means 6, 6' considered and, on the other hand, at least one secondary winding 8, 9 delivering a fault signal to the respectively associated detection and control module 3 or 3', this in the form of a signal induced at the level of the secondary when a differential fault occurs at the level of the corresponding primary.

As also shown in Figure 1, the two detection and control modules 3 and 3' are connected, at their output, through a circuit OR 11 to the single actuator, relay or similar means 5 of the device 1.

Of course, the two parallel and independent chains of measurement, detection, exploitation, processing and control, formed by the means 6, 6' and the modules 3, 3', comprise components constituents optimised in terms of reaction time, known to those skilled in the art.

It emerges from FIGS. 2 and 3 that the zone of overlap Z of the operational frequency domains of the two modules 3 and 3' is subdivided into two adjacent complementary frequency zones Z' and Z, in each of which one of the two modules 3, 3' respectively has a pre-dominant sensitivity and/or dominant reactivity, the sensitivities and/or reactivities of said modules 3, 3' being adjusted in such a way that the value of the frequency of passage from one pre-dominant zone to the other is at most equal to the value of the frequency of the monitored network, preferably less than the latter.

Advantageously, the respective curves C and C' of variation of the current sensitivity of the two modules 3 and 3’ as a function of the frequency presents a common point of intersection Pl, the value of the frequency of this point Pl being preferentially lower than the value of the frequency of the network or sector, and at most equal to the latter at the frequency of the network being monitored.

For a network frequency of 50 Hz for example, the frequency associated with the point PI may be between about 20 Hz and 50 Hz, preferably between 25 and 30 Hz.

Thus, each of the two modules 3 and 3' will selectively take over to provide protection, and thus trigger, if necessary, the means 5.

As shown in FIG. 1, and in accordance with additional features of the invention, it may be noted that:

-the first module 3 advantageously comprises, in addition to the excitation circuits 12, the processing of the fault signal 4 and the decision-making and control signal 13 of the actuator, the relay or the like 5, also conversion circuits AC / DC 14 and filtering 15, and / or,

-the second module 3' advantageously comprises, in addition to the circuits 4' for processing the fault and protection signal, and the circuits 16 for decision-making and control of the actuator, the relay or other means 5, also a circuit 17 performing a fire -break function and a means 18 for storing electrical energy.

Of course, the invention is not limited to the embodiment described and shown in the accompanying drawings. Modifications are possible, notably from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

1. Type B or B+ differential protection device for detecting leakage or fault current in an electrical installation powered by at least two-phase conductors of a network or by at least one phase conductor of a network and by a neutral conductor of said network, said device (1) comprising two distinct detection and control modules (3 and 3') each comprising at least one signal processing stage (4, 4') adapted and intended, firstly, to exploit a fault signal generated by the appearance of a differential fault at said network and, on the other hand, at controlling an electromagnetic actuator, relay or means for breaking or opening (5) the device (1) when said fault signal exceeds a frequency-dependent predetermined threshold value, each of said detection and control modules (3, 3') being functionally active or operational over a specific frequency range of its own, the device (1) characterized :

in that the two modules (3 and 3') are independent of each other and arranged so as to constitute two parallel and mutually independent detection channels, controlling the same actuator, relay or breaking means (5), in that each module (3, 3') is connected to its own and specific means (6, 6') for delivering a fault signal, in that a first (3) of the two modules (3, 3') is a detection and control module which is functionally active or operational for frequencies of the fault signal from 0Hz to a few tens of Hz, this first module (3) being powered by the network, and in that the second (3') of the two modules (3, 3') is a detection and control module which is functionally active or operational for frequencies of the fault signal of a few tens of Hz to at least 1 kHz, this second module (3') being autonomous in terms of power supply, and in particular not depending on the voltage of the network or of the sector, the frequency domains of the operational functioning of the two modules (3 and 3') mentioned above being partially overlapping.

2. Device according to Claim 1, characterized in that the two modules (3 and 3') each have a preponderant operation with respect to the other module (3', 3) on mutually complementary portions of the total frequency domain of the fault currents covered by said device (1).

3. Device according to Claims 1 or 2, characterized in that the first module (3) for detection and control, depending on the voltage of the network, is a sensitive differential protection module and which reacts to the smoothed direct fault currents, to low frequency and / or with a large DC offset.

4. Device according to any one of Claims 1 to 3, characterized in that the second module (3') for detection and control is a type F differential protection module, optionally incorporating a function of the fire-break, the operation of said second module (3'), including the realisation of the aforementioned function, being independent of the voltage of the network or of the sector.

5. Device according to any one of Claims 1 to 4, characterized in that each of the own means (6 and 6') for issuing a fault signal consists of a toroid (7, 7') of ferromagnetic material comprising, on the one hand, a primary winding formed by one of the conductors (2, 2') of the monitored network or by an excitation winding (10), according to the means (6, 6') considered and, on the other hand, at least one secondary winding (8, 9) delivering a fault signal to the respectively associated detection and control module (3 or 3'), this in the form of a signal induced at the level of the secondary during the occurrence of a differential fault at the level of the corresponding primary.

6. Device according to any one of Claims 1 to 5, characterized in that the two detection and control modules (3 and 3') are connected, at their output, via a circuit OR(ll) to the single actuator, relay or breaking or opening means (5) of the device (1).

7. Device according to any one of Claims 1 to 6, characterized in that the overlapping zone (Z) of the frequency domains of the operational functioning of the two modules (3 and 3') is subdivided into two complementary frequency zones (Z¹and Z), in each of which one of the two modules (3, 3') has respectively a sensitivity and / or a predominant reactivity, the sensitivities and / or reactivities of said modules (3, 3') being adjusted in such a way that the value of the frequency of passage from one preponderance zone to the other is at most equal to the value of the frequency of the monitored network, preferentially lower than the latter.

8. Device according to any one of Claims 1 to 7, characterized in that the two modules (3 and 3') being configured in such a way that their respective curves (C and C') of variation of the current sensitivity in function of the frequency present a common point of intersection (PI), the value of the frequency of this point (PI) being preferentially lower than the value of the frequency of the network or the sector, and at most equal to the latter at the frequency of the monitored network.

9. Device according to any one of Claims 1 to 8, characterized in that the first module (3) comprises, in addition to the excitation circuits (12), the fault signal processing (4) and the decision-making and control (13) of the actuator, the relay or breaking means (5), also AC / DC conversion circuits (14) and filtering (15).

10. Device according to any one of Claims 1 to 9, characterized in that the second module (3') comprises, in addition to the circuits (4') for processing the fault and protection signal, and the circuits (16) for decision-making and control of the actuator, the relay or breaking means (5), also a circuit (17) performing a fire-break function and means (18) for storing electrical energy.

1/2

Fig. 1

Trigger point (mA)

Frequency (Hz) crq’ Tri • h-“

GJ 7° τ/τ