SE539901C2

SE539901C2 - A leak sensor

Info

Publication number: SE539901C2
Application number: SE1651261A
Authority: SE
Inventors: Berggren Lars
Original assignee: Esib Electronics Ab
Priority date: 2016-09-23
Filing date: 2016-09-23
Publication date: 2018-01-09
Also published as: SE1651261A1

Abstract

The disclosure relates to a leak sensor (100) for locating water leakage underneath a water proof membrane, comprising: a conductor bundle (110) comprising a plurality of insulated conductors (C1-C6), arranged in a cable adjacent to each other, wherein the conductor bundle (110) comprises at least two sensing areas (P1-P15) along the extension of the conductor bundle, wherein, at each sensing area (P1-P15), each conductor has a measurement portion (120), arranged to be either in a measurement mode (122) where an opening is arranged in the insulation, or in a non-measurement mode (124) where the insulation is intact in a, for the conductor bundle (110), unique combination forming a unique binary position sequence (140). The disclosure also relates to a system (200) and a water-proof roof covering material comprising the leak sensor (100). The disclosure also relates to a method for locating water leakage underneath a water proof membrane.

Description

A LEAK SENSOR Field of the inventionThe present disclosure relates to a leak sensor for detecting water leakagein a roof. l\/lore specifically, the disclosure relates to a leak sensor utilizing electrical conduction between conductors.

Background artLeak sensors making use of electrical conductivity are known in the art.

Typically, they are based on measuring the electrical conductivity between at leasttwo electrical conductors positioned electrically isolated from each other underneaththe roof water resistant membrane. ln case of a leak, the electrical conductivitybetween the two conductors will increase, thus making it possible to detect the leak.

One example of such a leak sensor is disclosed in US patent applicationUS4965554 A, disclosing two bundles of wires each bundle comprising a plurality ofstraight conductors arranged parallel to each other, the two bundles being arrangedon top of each other such that each wire in the plurality of wires in the first bundleforms a right angle to each wire in the plurality of wires in the second bundle. Theconductors in the first bundle are physically separated from the conductors in thesecond bundle. ln case water occurs at a position where two wires cross, and thetwo wires have different electrical potential, a leak current will occur. By identifyingwhich pair of conductors between which the leak current was detected, the positionof the leak can be obtained.

One problem with the leak sensor described hereinabove is its complexity.Two bundles of wires need to be arranged electrically isolated from each other,covering the entire roof area of interest. Moreover both bundles of wires must beconnected to an electrical system arranged to, separately, assign potential difference between each combination of crossed wires.

Summarylt is an object to mitigate, alleviate or eliminate one or more of the above- identified deficiencies in the art and disadvantages singly or in any combination andsolve at least the above mentioned problem. 2 According to a first aspect, these and other problems are solved in full, or atleast in part, by a leak sensor for locating water leakage underneath a water proofmembrane, comprising: a conductor bundle comprising a plurality of insulatedconductors arranged in a cable adjacent to each other, wherein the conductor bundlecomprises at least two sensing areas along the extension of the conductor bundle,wherein, at each sensing area, each conductor has a measurement portion,arranged to be either in a measurement mode where an opening is arranged in theinsulation, or in a non-measurement mode where the insulation is intact, wherein theshortest distance between tvvo sensing areas is much larger than the longestdistance between the insulated conductors, wherein the extension of the sensingareas along the direction of the conductors is much shorter than the shortestdistance between two sensing areas, wherein, at each sensing area, at least two ofthe measurement portions are arranged to be in the measurement mode, andwherein, at each sensing area, the individual insulated conductors havemeasurement portions, arranged in either the measurement mode or the non-measurement mode in a, for the conductor bundle, unique combination forming aunique binary position sequence.

The design of the leak sensor allows determining at which sensing area theleak occurred without having to resort to complex two-dimensional structures. Thesensor extends in only one dimension but allows for detecting the position of a waterleak in two dimensions. Moreover, the solution is cheap and relatively easy tomanufacture.

The leak sensor may be arranged in a linear configuration, wherein theconductor bundle is arranged as a straight line. A plurality of leak sensors may bearranged in parallel to each other thus providing a coverage of a roof. The leaksensor may, alternatively or additionally, be arranged along a curved path. Such apath could for example be a loop arranged such that one single leak sensor formssub sections essentially parallel to each other, thus providing a coverage of a roofarea. According to one embodiment, the cable bundle is arranged with the insulatedcables parallel to each other in a plane. This thin flat embodiment may allow easierpositioning of the sensor between layers of roof covering etc.

According to one embodiment, the leak sensor further comprises a waterabsorbing material which is arranged to be in contact with all measurement portionswithin a sensing area which are in the measurement mode.

According to one embodiment, one of the plurality of insulated conductors is 3 a reference conductor having all of its measurement portions arranged in themeasurement mode.

The use of a reference conductor allows for a faster and easier measurementsequence. lnstead of having to measure the leak current between all combinations ofconductors, it suffices to measure the leak current between the reference conductorand each of the other conductors.

According to one embodiment, tvvo of the plurality of insulated conductors arereference conductors having all of their measurement portions arranged in themeasurement mode.

The use of two reference conductors allows for triggering the system toinitiate measurement only when needed. By regularly measuring the leak currentbetween the two reference conductors, the occurrence of a leak current can bedetected. The measurements cannot resolve the position of the leak, but theoccurrence of a reading between the two reference conductors may be used totrigger the electronics to initiate the rest of the sensor for measurement. This allowssaving energy.

According to a second aspect, a system is provided, the system comprising: aleak sensor according to the disclosure, a control circuitry comprising: voltagegenerator arranged to generate an electrical potential, a resistance sensor unitarranged to detect a resistance, a memory arranged to store a library of the uniquebinary position sequences of the leak sensor, the control circuitry being arranged toapply an electrical potential generated by the voltage generator between any twoconductors of the plurality of conductors of the leak sensor, and to detect, using theresistance sensor unit, the resistance between said pair of conductors.

According to one embodiment, the control circuitry is electrically connected tothe conductor bundle by a conductive material.

According to one embodiment, the control circuitry is coupled to the cablebundle using induction.

The leak sensor may also be used in a passive mode. ln the passive mode, apotential is applied from outside, for example from electrodes placed on or close tothe roof covering material on the roof. ln case of a leak in the roof covering material,one or more leak currents may be detected using the leak sensor located under theroof covering material. The location of the leak may be determined by the uniquecombination of conductors being in the measurement mode in each sensing area.

According to a third aspect, a water-proof roof covering material is provided, 4 the water-proof roof covering material comprising the leak sensor according thedisclosure, wherein the leak sensor is structurally integrated into the roof coveringmaterial.

This may be advantageous as it allows for an easier process of installing thesenson According to a fourth aspect, a water-proof roof covering material is provided,the water-proof roof covering material comprising the system according to thedisclosure, wherein the system is structurally integrated into the roof coveringmaterial.

According to a fifth aspect, a method for locating water leakage underneath awater proof membrane using the system of the disclosure is provided, the methodcomprising the steps of: applying, consecutively, an electrical potential between atleast one reference conductor and each one of the remaining insulated conductorsin the conductor bundle, detecting, consecutively, a resistance value between the atleast one reference conductor and each one of the remaining insulated conductors ofthe conductor bundle, wherein detection of a resistance smaller than a thresholdvalue between a pair of conductors is interpreted as a result from a leak current in-between said pair of conductors at a sensing area within which both of theconductors have measurement portions being in the measurement mode, deriving adetected binary code sequence based on the detected resistance values, whereineach of the remaining insulated conductors will be associated with one position inthe code sequence, said position obtaining 1 for a detected leak current and 0 for nodetection of leak current, comparing the detected binary code sequence with thelibrary of binary code sequences to find a match, thus allowing obtaining within whichsensing area the leak current occurred.

According to a sixth aspect, a method for locating water leakage underneatha water proof membrane using the system of the disclosure is provided, the methodcomprising the steps of: applying, consecutively, an electrical potential between eachcombination of a pair of insulated conductors from the plurality of insulatedconductors in the conductor bundle, detecting, consecutively, a resistance valuebetween each combination of a pair of insulated conductors from the plurality ofinsulated conductors in the conductor bundle, deriving an integer code sequencebased on the detected resistance values, wherein each of the combinations of a pairof insulated conductors will be associated with one position in the integer codesequence, said position obtaining the integer N for a detected leak current and 0 for 5 no detection of Ieak current, wherein the integer N is calculated as the ratio betweenthe detected resistance and a nominal resistance, said ratio being rounded to theclosest integer, wherein said nominal resistance is the resistance measured betvveena pair of conductors when Ieak currents occur in only one sensing area within whichboth conductors in the pair of conductors have its measurement portions arranged inthe measurement mode, analyzing the detected integer code sequence to establishwhich two or more position code sequences out of the library of position codesequences that correspond to the detected integer code sequence, thus allowingobtaining within which two or more sensing areas the Ieak currents occurred.

The second, third, fourth, fifth and sixth aspects may generally have the samefeatures and advantages as the first aspect. lt is further noted that the inventiveconcepts relate to all possible combinations of features unless explicitly stated othen/vise.

Brief descriptions of the drawinqs The inventive concept will by way of example be described in more detail withreference to the appended schematic drawings, which shows presently preferredembodiments.

Figure 1 shows a schematic view of the Ieak sensor according to anembodiment of the present disclosure.

Figure 2 shows a schematic view of the system according to an embodiment of the present disclosure.

Detailed descriptionThe present inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferredembodiments are shown. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to the embodiments set forthherein; rather, these embodiments are provided for thoroughness and completeness,and fully convey the scope of the disclosure to the skilled person.Fteferring to Fig. 1, a Ieak sensor 100 is shown schematically in a top view.

The Ieak sensor 100 is used for locating water leakage underneath a water proof membrane. Such a membrane could be for example the roof covering material on a flat roof. The leak sensor 100 comprises a conductor bundle 110 comprising aplurality of insulated conductors C1-C6, arranged in a cable adjacent to each other.The conductor bundle 110 comprises at least two sensing areas P1-P15 along theextension of the conductor bundle. At each sensing area P1 -P1 5, each conductorhas a measurement portion 120, arranged to be either in a measurement mode 122where an opening is arranged in the insulation, or in a non-measurement mode 124where the insulation is intact. The shortest distance 130 between two sensing areasis much larger than the longest distance 132 between the insulated conductors C1-C6. Additionally, the extension of the sensing areas along the direction of theconductors is much shorter than the shortest distance 130 between two sensingareas. At each sensing area P1-P15, at least two of the measurement portions 120are arranged to be in the measurement mode. Moreover, at each sensing area P1 -P15, the individual insulated conductors C1-C6 have measurement portions 120,arranged in either the measurement mode or the non-measurement mode in a, forthe conductor bundle 110, unique combination forming a unique binary positionsequence 140.

By individually assigning an electrical potential difference between each ofthe conductors within each pair of conductors in the conductor bundle, it is possibleto detect the occurrence of a leak current and assign said occurrence to a specificpair of conductors. The openings in the insulation (i.e. corresponding to themeasurement portion being in a measurement mode) are arranged such that ameasurement series covering all possible combinations of pairs in the bundle, C1-C2, C1-C3, C1-C4, C1-C5,C1-C6,C2-C3 ...etc. Thus there only exists one possiblesensing area in which a specific outcome will occur. This makes it possible to infer atwhich sensing area the leak occurred.

The cable bundle may be arranged with the insulated cables parallel to eachother in a plane.

The leak sensor may further comprise a water absorbing material which isarranged to be in contact with all measurement portions within a sensing area whichare in the measurement mode.

The leak sensor may have one of the plurality of insulated conductors actingas a reference conductor having all of its measurement portions arranged in the measurement mode. This is illustrated in Fig. 1 (conductor C1) The leak sensor may have two of the plurality of insulated conductors actingas a reference conductor having all of its measurement portions arranged in themeasurement mode. This is illustrated in Fig. 1 (C1 and C6).

A system 200 will now be described with reference to Fig. 2. The system 200comprises a leak sensor 100 according to one of the embodiments disclosed herein.The system 200 further comprises a control circuitry 210 comprising: a voltagegenerator 224 arranged to generate an electrical potential, a resistance sensor unit220 arranged to detect a resistance and a memory 226 arranged to store a library ofthe unique binary position sequences of the leak sensor. The control circuitry 210 isarranged to apply an electrical potential generated by the voltage generator 224between any tvvo conductors of the plurality of conductors of the leak sensor 100,and to detect, using the resistance sensor unit 220, the resistance between said pairof conductors.

The system 200 may further comprise a control unit 222 arranged for initiatingdetection using the leak sensor 100. The system 200 may further comprise at leastone multiplexer 230,232 arranged to allow consecutive measurements betweenselected pairs of conductors to be carried out.

The control circuitry 210 may be electrically connected to the conductorbundle by a conductive material. Alternatively, or additionally, the control circuitrymay be coupled to the cable bundle using induction. ln such a case, power and/orelectrical signals are transferred between the control circuitry and the conductorbundle by electromagnetic induction created in coils typically located close to eachother.

Examples of such techniques are near field communication, NFC, Radiofrequency identification, RFID. lt is understood that many alternative embodimentsexist in which the system is arranged to not have physical contact but still couple toeach other in alternative ways, such as for example capacitive coupling and/orradiative techniques comprising electromagnetic waves.

The leak sensor according to any embodiment herein may be structurallyintegrated into a water-proof roof covering material.

The system according to any embodiment disclosed herein may bestructurally integrated into a roof covering material. The system may be powered and/or communicated with using wired coupling. Alternatively, or additionally, the system may be powered and/or communicated with using inductive coupling. ln oneembodiment, the system is powered and communicated with only at scheduledoccasions. A user then locates a secondary device in a specified area on top of theroof. The secondary device couples inductively with the system under the water-proof roof covering material. The secondary device may then, by said inductivecoupling, power the system. The secondary device may additionally, by saidinductive coupling, communicate with the system. lt is to be understood that thesystem 210 may be partly integrated into the secondary device. For example, thevoltage generator 224 may be part of the secondary device and thus not integratedunder the roof covering material. lt is to be understood that further structural featuresmay be needed, such as for example a communication interface, transmitting andreceiving units etc.

A method for locating water leakage underneath a water proof membrane willnow be described. The method utilizes an embodiment of the leak sensor and/or thesystem comprising at least one reference conductor. The method comprises thesteps of: - applying, consecutively, an electrical potential between at least onereference conductor C1,C6 and each one of the remaining insulated conductors C2-C5 in the conductor bundle 110, - detecting, consecutively, a resistance value between the at least onereference conductor C1,C6 and each one of the remaining insulated conductors C2-C5 of the conductor bundle 110, wherein detection of a resistance smaller than athreshold value between a pair of conductors is interpreted as a result from a leakcurrent in-between said pair of conductors at a sensing area P1 -P1 5 within whichboth of the conductors have measurement portions 120 being in the measurementmode, - deriving a detected binary code sequence 150 based on the detectedresistance values, wherein each of the remaining insulated conductors C2-C5 will beassociated with one position in the code sequence, said position obtaining 1 for adetected leak current and 0 for no detection of leak current, - comparing the detected binary code sequence 150 with the library of binarycode sequences to find a match, thus allowing obtaining within which sensing area the leak current occurred.

Sometimes a water Ieak may be extended to cover more than one sensingarea, hence allowing for more than one Ieak current to be formed. ln such a case,the Ieak currents will occur in parallel and hence the detected resistance value willbe lower than from a nominal resistance value detected in a case where only oneIeak current occurs in one sensing area (i.e. from a case with a smaller Ieak). As theresistance is expected to be similar in every sensing area in which a Ieak has beenformed, it is possible to determine the number of sensing areas in which Ieakcurrents have been formed in parallel by comparing the detected resistance value tothe nominal resistance value. This requires the system to measure the resistancevalue between each combination of pairs of conductors in the conductor bundle.

A method for locating water leakage underneath a water proof membraneutilizing the concept disclosed hereinabove will now be described. The methodutilizes an embodiment of the Ieak sensor and/or the system without referenceconductors. The method comprises the steps of: - applying, consecutively, an electrical potential between each combination ofa pair of insulated conductors from the plurality of insulated conductors C1-C6 in theconductor bundle 110, - detecting, consecutively, a resistance value between each combination of apair of insulated conductors from the plurality of insulated conductors C1-C6 in theconductor bundle 110, - deriving an integer code sequence based on the detectedresistance values, wherein each of the combinations of a pair of insulatedconductors will be associated with one position in the integer code sequence, saidposition obtaining the integer N for a detected Ieak current and 0 for no detection ofIeak current, - wherein the integer N, for each pair of insulated conductors, is the numberof sensing areas, within which both conductors in the pair of conductors have itsmeasurement portions arranged in the measurement mode, in which Ieak currentshave been detected between the insulated conductors in the pair of insulatedconductors, said number being derived by comparing the detected resistance valueto a nominal resistance, wherein said nominal resistance is the resistance measured between a pair of conductors when Ieak currents occur in only one sensing area within which both conductors in the pair of conductors have its measurementportions arranged in the measurement mode, - analyzing the detected integer code sequence to establish which tvvo ormore position code sequences out of the library of position code sequences thatcorrespond to the detected integer code sequence, thus allowing obtaining withinwhich two or more sensing areas the Ieak currents occurred.

The embodiments herein are not limited to the above described examples.Various alternatives, modifications and equivalents may be used. Therefore, thisdisclosure should not be limited to the specific form set forth herein. This disclosureis limited only by the appended claims and other embodiments than the mentioned above are equally possible within the scope of the claims.

Claims

11 CLA|I\/IS

1. A leak sensor (100) for locating water leakage underneath a water proofmembrane, comprising: a conductor bundle (110) comprising a plurality of insulated conductors (C1-C6), arranged in a cable adjacent to each other, wherein the conductor bundle (110) comprises at least two sensing areas(P1-P15) along the extension of the conductor bundle, wherein, at each sensing area(P1-P15), each conductor has a measurement portion (120), arranged to be either ina measurement mode (122) where an opening is arranged in the insulation, or in anon-measurement mode (124) where the insulation is intact, wherein the shortest distance (130) between two sensing areas is muchlarger than the longest distance (132) betvveen the insulated conductors (C1-C6), wherein the extension of the sensing areas along the direction of theconductors is much shorter than the shortest distance (130) between two sensingareas, wherein, at each sensing area (P1-P15), at least two of the measurementportions (120) are arranged to be in the measurement mode, and wherein, at each sensing area (P1-P15), the individual insulated conductors(C1-C6) have measurement portions (120), arranged in either the measurementmode or the non-measurement mode in a, for the conductor bundle (110), unique combination forming a unique binary position sequence (140).

2. The leak sensor (100) according to claim 2, wherein the conductor bundle(110) is arranged with the insulated conductors (C1-C6) parallel to each other in a plane.

3. The leak sensor (100) according to any one of the preceding claims, furthercomprising a water absorbing material which is arranged to be in contact with allmeasurement portions (120) within a sensing area which are in the measurement mode. 12

4. The leak sensor (100) according to claim 1-3, wherein one of the pluralityof insulated conductors (C1-C6) is a reference conductor (C1) having all of its measurement portions (120) arranged in the measurement mode (122).

5. The leak sensor according to claim 1-3, wherein tvvo of the plurality ofinsulated conductors (C1-C6) are reference conductors (C1, C6) having all of their measurement portions (120) arranged in the measurement mode (122).

6. A system (200) comprising: a leak sensor (100) according to any one of the preceding claims,a control circuitry (210) comprising: a voltage generator (224) arranged to generate an electricalpotential, a resistance sensor unit (220) arranged to detect a resistance, a memory (226) arranged to store a library of the unique binaryposition sequences of the leak sensor, the control circuitry (210) being arranged to apply an electricalpotential generated by the voltage generator (224) between any tvvoconductors of the plurality of conductors (C1-C6) of the leak sensor,and to detect, using the resistance sensor unit (220), the resistance between said pair of conductors.

7. The system (100) according to claim 6, wherein the control circuitry (210) is electrically connected to the conductor bundle (110) by a conductive material.

8. The system (100) according to claim 6, wherein the control circuitry (210) is coupled to the conductor bundle (110) using induction.

9. A water-proof roof covering material comprising the leak sensor (100)according to anyone of claims 1-5, wherein the leak sensor (100) is structurally integrated into the roof covering material. 13

10. A water-proof roof covering material comprising the system (200)according to anyone of claims 6-8, wherein the system (200) is structurally integrated into the roof covering material.

11. A method for locating water leakage underneath a water proof membraneusing the system of claim 6-8 when dependent on claim 4-5, the method comprisingthe steps of: - applying, consecutively, an electrical potential between at least onereference conductor (C1,C6) and each one of the remaining insulated conductors(C2-C5) in the conductor bundle (110), - detecting, consecutively, a resistance value between the at least onereference conductor (C1,C6) and each one of the remaining insulated conductors(C2-C5) of the conductor bundle (110), wherein detection of a resistance smallerthan a threshold value between a pair of conductors is interpreted as a result from aleak current in-between said pair of conductors at a sensing area (P1-P15) withinwhich both of the conductors have measurement portions (120) being in themeasurement mode, - deriving a detected binary code sequence (150) based on the detectedresistance values, wherein each of the remaining insulated conductors (C2-C5) willbe associated with one position in the code sequence, said position obtaining 1 for adetected leak current and 0 for no detection of leak current, - comparing the detected binary code sequence (150) with the library ofbinary code sequences to find a match, thus allowing obtaining within which sensing area the leak current occurred.

12. A method for locating water leakage underneath a water proof membraneusing the system of claim 6-8 when dependent on claim 1-3, the method comprisingthe steps of: - applying, consecutively, an electrical potential between each combination ofa pair of insulated conductors from the plurality of insulated conductors (C1-C6) inthe conductor bundle (110), 14 - detecting, consecutively, a resistance value between each combination of apair of insulated conductors from the plurality of insulated conductors (C1-C6) in theconductor bundle (110), - deriving an integer code sequence based on the detectedresistance values, wherein each of the combinations of a pair of insulatedconductors will be associated with one position in the integer code sequence, saidposition obtaining the integer N for a detected Ieak current and 0 for no detection ofIeak current, - wherein the integer N, for each pair of insulated conductors, is the number ofsensing areas, within which both conductors in the pair of conductors have itsmeasurement portions arranged in the measurement mode, in which Ieak currentshave been detected between the insulated conductors in the pair of insulatedconductors, said number being derived by comparing the detected resistance valueto a nominal resistance, wherein said nominal resistance is the resistance measuredbetween a pair of conductors when Ieak currents occur in only one sensing areawithin which both conductors in the pair of conductors have its measurementportions arranged in the measurement mode, - analyzing the detected integer code sequence to establish which two ormore position code sequences out of the library of position code sequences thatcorrespond to the detected integer code sequence, thus allowing obtaining within which two or more sensing areas the Ieak currents occurred.