Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
Field of the Invention
.. . . _ . . .
This invention relates to methods and apparatus for
detecting and obtaining information about (particularly locating)
changes in variables.
Introduction to the Invention
A number of methods have been used (or proposed for
use) to detect changes in variables along an elongate path, e.g.,
the occurrence of a leak (of water or another liquid or gas,
insufficient or excessive pressure, too high or too low a them-
portray, the presence or absence of light or another form of
electromagnetic radiation, or a change in the physical position
of a movable member, e.g. r a valve in a chemical process plant
or a window in a building fitted with a burglar alarm system.
Changes of this kind are referred to in this specification by
the generic term "event". Such detection methods are for example
highly desirable to detect leaks from steam lines into thermal
insulation surrounding such lines, leaks from tanks and pipes
containing corrosive or noxious chemicals, or leakage or condemn-
station of water under floors or within telecommunication or
electrical power systems. Some of these known methods not only
signal when the event takes place/ but also indicate the location
of the event. However, the known methods which indicate the
location of the event suffer from serious disadvantages. For
I ~2~2~6
example, they make use of time domain reflectometer techniques
(and are, therefore, expensive), and/or give unreliable results
when used over usefully long elongate paths or under conditions
when there may be a substantial and unknown variation along the
length of the path of a variable which affects the accuracy of
the measurement (especially temperature), and/or make use of
electrical conductors whose primary purpose it to carry a current
(e.g., a telecommunication signal under normal operating con-
dictions (and which therefore have resistance and uniformity
characteristics consistent with that purpose), and/or cannot
be used when the event causes electrical connection between two
conductors through a connection which is of high or inditer-
minute resistance, e.g., an tonically conductive connecting
element. Reference may be made for example to United States
Patents Nos. 1,084,910, 2,581,213, 3,248,646, 3,384,493, 3,800,216,
and 3,991,413, United Kingdom Patent No. 1,481,850 and German
Offenlegungschriften Nos. 3,001,150.0 and 3,225,742.
SUMMARY OF THE INVENTION
In accordance with the present invention, we have now
discovered an improved method and apparatus for monitoring for
the occurrence of an event and for detecting and obtaining
information about the event upon its occurrence (i.e., as soon
as it occurs or at some time after it has occurred). In this
method,
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4 1~525~
upon o~urrence Do the event, at lest one electrical
connection it made between Doris member end 8
locating ember ox known i~pedence corrector Tao the
connection or connection being effective at n first
point at which the event tykes place (or whose locution
it defined by Bore other oharacteri6tic ox the event
A current of known size it then driven through the
electrical connection and town the locating member
to a second print whose locution it known. The voltage
drop between the first and ~ecsnd points it then
measured end the locution of the first point can then
be determined. the system preferably makes use of a
locating member hiving an impedance which is selected
to give desired degree of 3rcuracy in locating the
first print, end which preferably does not very subst~nt-
tally within the temperature range in which the system
operate.
hen the occurrence of the overt onuses a single
or very short connection to be mode between the locating
20 member and the source member, then the "first point"
Jill of course be easily identi~ieJ, since it it the
only connect point. However, when the event results
- in connection acted or Gore spcced-apart lccati~ns
and/or over finite length of the locating member the
First pontoon . the point whose lDc~tion eon be
determined prom the observed volt drop, is owe
intermediate point which can conveniently be referred
to en the Electrical center of the various connections.
If there are connection it two or more spaced-apart
30 locations, the electoral center" may be sty e location
at which there it no connection between the locating
Ed source menders. It is for this reason that the
connection to the toasting member is onetime referred
to herein as being effective" at the first point.
MP0869
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. -5-
i
HDwe-~er, it it; to be understood that where reference is
jade her o the ccnne~ti~n being jade" et the first
point, this it intended to include situ~ti~n~ in which
a plurality of electrical oonn~ctions are sue between
the locating member end the source member, with the
electrical center of the sanction being at the first
point. In many Chihuahuas, the first point will be at, or
clove to, that point at which e connection is made and
which it closest ED the second point; however, it is
important to realize that this it not necessarily the
case .
he invention overcome one or more of the
disadvantage of the known processes. For many uses, a
particularly important advantage it that the information
obtained can be independent of the impedance of the
connection to the locating member, i.e. the infornatinn
obtained remains the save even if a sub6tantiel sod
unknown change it made in the impedance of the connection.
In one aspect t the invention provides a method for
monitoring for the occurrence of an event, sod or
detecting God obtaining information about the event
upon its occurrence which method comprises providing
a system in which, upon Dccurrenre Do the event,
(1) electrical connection 8 made between us
electrically conductive kowtowing member and an
electrically conductive sourer member;
the connection to the locating member being effective
at a first print whose location is defined by et
least one characteristic of the event;
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I I
the making of the connection enabling the
fourteen of a text circuit which caprices
(I the connection, (b) that part of the locating
umber which lips bæt~c~n the first point and a
second point having a known location on the
locating member, and (c) a power source which
cause an electrical current of known foe to be
transited between the first end second point on
the locating member; end
the current end the locating member being such
that, by measuring the voltage drop between the
first and second points the spatial relationship
between the first and second point con be determined;
(2) the voltage drop between the forfeit
and end points is erred; on
I information concerning the event it obtained
from the measurement jade in to I
Preferably the voltage drop between the first
and second point it determined by jeans of a voltage-
erring dsvico which form part of a reference
irrupt, the reference circuit comprising
I) the volta~e-~oasuring device
(b) that part of the locating member which lit
- between the first end second point, end
(c) on electrically conductive return member which
(i) it electrically connected to the locating
member at thy second print and at soother
point on the locating member whose distance
MP0&69
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fry the secDn~ point is it least en great as
the dunce iron the second point to the
first put, hot distance being measured
along the locating member, end it I
otherwise insulated from the locating member 9
the volt~ge-me~suring device hiving an impedance which
is very high ho comparison with any unknown port of the
impedance of the other components of the reference circuit.
. the invention alto includes apparatus suitable
for carrying out the method of the invention in
particular apparatus comprising
(1) an elongate electrically conductive locating
member whose impedance from one end to any
point on the locating member defines the
spatial relationship between that end
and that point;
(2) an elongate electrically conductive source
! member;
(3) on event-sensitive connection means which,
upon occurrence of sun event, effects electrical
connection between the locating member end the
source member, the connection being effective it a
first point on the locating member which to
defined by at lust one chsr~cteristic of the
vent;
(4) voltegs-me~suring device for determining the
voltage drop between the first point sod a
second point which it it one end of the
loosing member; and
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I power source which it electrically connected
Jo the Elecond point on the lofting Norway end which,
in the absence of sun event, I riot otherwise
connected to the locating member, so that,
when occurrence of on event causes sun electrical
connection to be made between the locating
and source eerily this enable the formation of
a text circuit which comprises (~) the connection,
(b) that part of the locating member which
I Lowe between the first end second points, and
I the power source, end in which test circuit
e current of known size is transmitted between
the first and second points on the locating
member.
The invention alto includes novel elongate articles
which can be used in the method end apparatus of the
invention in particular articles which comprise
(A) sun elongate ore which is composed of metal
whose temperature coefficient of resistlvity
overages Lowe than 0.003 per degree Centigrade over
- the temperature range 0 to 100C end in
.. which each longitudinal section has e resistance
high is from 10 4 in 104 ohms/ font and
(B) an elongate jacket which is composed no a
conductive polymer which electoral
surrounds the core, and in which each longitude
final section has 8 resistance which is
et least lD0 times the resistance of the core
of that longitudinal section By all tempers-
lures from 0 to lode
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~225;~:S~
Aries DES~RIPIlOtS I TOE CROWING
.
ye inven~lon lo illustrated in the scco~panying
drawing, on which
Figure l is a generalized schematic circuit
diagram of the method of the present invention,
Figures 2-24 are ~chemstic circuit diagrams of the
method and apparatus of the invention,
Figure 25-27 are graphs showing how the voltage
drop between the first and second points
on the looting member con vary in different
systems of the invention, end
inure 28-33 are diagrammatic cro~s-sections
through apparatus of the invention.
DETAILED DESCRIPTION OF THY INVENTION
.
In the interests of laureate the following detailed
description of the invention include sections which
are off or exclusively concerned with a particular
port of the invention. It it to be understood, however,
that the relationship between different part of the
20 invention it of s~nificant importune, and the following
detailed description should be rest in the light of
that understanding. It should also be understood that,
where features of the invention are described in the
context of particular Figures of the drawing, the same
I description con ~15D be applied to the invention in
general and to the other Figures, insofar us the
context permit
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1. TOE ELECTRICAL CHARACTERISTICS OF THE INVENTION
. .
he basic electrical char~cteristic6 of the
invention can bet be understood by reference to
Figure 1, which schematically represents a sub6t~nti~1
number of the preferred methods and apart of the
invention. In Figure I, there i an elongate lDceting
Dumber 11, on elongate source member 12, e voltage-
erring device 14, power source 15 end an elongate
return member 16. the source member it electrically
. connected, through the power sure to one end of the
locating member; in the absence of on event, there is
no Dither electrical connection between the locating
member and the source member. Between the course end
locating members (but not shown in Figure 1) it an
event sensitive connection ennui (this term being used
to include a continuous event-sen~itive connection
means and a plurality of ~peced-ap~rt event-~en~itive
connection means) which becomes conductive it any
location at which an event take place In Figure 1,
I an event his token place at a final point 1 which lies
somewhere on the locating member, but whose location it
other unknown. As-a result ox the event, an
electrical connection E his been jade between the
locating end source member. The power source 15 it
connected via connection ennui 152 to the toasting
member at one end thereof, designated by the numeral 2
which is the "second point" in two definitions given
above of the method and epparetus of the invention.
(Th~.secDnd point could be it any point of known
locution between the end of toasting member 11 end the
connection point 1, providing that the voltage-meesurin~
device it 3rrsnged to measure the voltage drop between
the first and second pointer) The power source it also
connected to the source member; US Schematically
indicted by the plurality of connection 151, the
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L~:5;25~
connection between thy power source and the source
eyebrow can be ye it sty one or Gore points on the
source err, Further the ~Dnnection~ cfln be
of err end unknown pudency, providing the power
source con drive a known current between the first and
end points of the locating member. Thus the making
of the connection at point 1 results in the formation
of 3 test circuit which includes the connection, the
toasting member between points 1 and 2, the power
source and (unwell a jingle connection 151 it made
between the pies source nod the source member at the
connection point part of the source member.
The v~ltage-mes~uring device it connected to the
second point 2 on the locating member (via the return
member 16) and it also connected to the locating member
at one or more point whose distance from the second
point is it lest us far us the first point 1, as
schematically indicated by the plurality of connections
141, these connection mutt be of known impedance or sun
ED impedance which is very small by comparison with the
impedance of the volt~ge-measuring device. Thus the
voltage-measuring device forms part of a reference
circuit which comprises the device it least that part
of the locating member between points 1 and 2, and top
return member.
he power source 15 end the voltage-meRsuring
device 14 own be connected to the point on the
toasting member 11 in any convenient Jay. Thus, so
indicated by the plurality of connections 153, the
ED connection member 152 and the return member 16 can be
connected to each other at any one or more locutions.
It will be teen that the locution of print 1
can be calculated of the following are known:-
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(a) thy current phony between points and 2,
(b) the pudency ox the ~o~pDnents of the
reference circuit,
(c) the voltage drop measured by the voltage-
measuring device,
(d) the location of point 2, and
(I thy i~pedanre of the locating member between
print 2 end etch point on the lDcsting member.
Systems in which these features are known con be
provided in a number of different aye. The accuracy
with which the first point can be located is limited by
the ratio of the impudency of the voltage-measuring
device to any unknown part of the impudence of the
other components of the reference circuit; and in most
cases it is convenient to use component such that the
ratio of the impedance of the device to the total
impedance of the ret of the reference circuit is very
high, Accordingly, these ratio should preferably be
it least 100, particulfirly it least Lowe, especially
at least Lydia. It I for these reasons tint the
connection 141 and 153 on Figure 4 ore shown I having
ID resistance. by counterweight the ruttiness of the .. Connection between the locating and Ursa members, sod
the rustiness of the other components of the text
circuit do nut affect the accuracy of the information
- obtained; this is on important advantage of the invention.
2; INFORMATION WHICH CAN YE PROVIDED ABOUT AN EVENT
, The method of the invention not only detect
that a particular event has taken plower but sly
provides information bout the event. In many case,
the information provided bout the event is it location,
particularly when the vent takes place et (or near)
the locution ox the first point.
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.
over, gee infuriation providet1 con be Dither inform
lion; jot expel ho the ~e~perat~ t a particular
location Swing ~onitu~ed7 Dyne pin on thy locating
umber can be identified when the temperature I in one
temperature range an another point eon be identified
when the temperature it in n different temperature
range. As jut noted, the locution of the event may
be at, Dry clue to, the first point on the locating
member. Hs~ev~ it it not necessarily so; for
example, one or ore remote event-detecting stations
can be connected electrically or otherwise 9 to different
points on n central toasting member, the locations of
the connection punt being ch~rncteristic of the
locations of the event-detecting stations. the method
of the invention will provide some, but nut niece ssrily
9119 the desired information about the event. For
example, the method can usefully be employed to determine
that a given event (e.g. the opening of a valve) has
token place at one or Gore Do a relatively smell number
of different locutions, out of a relatively large
number of possible locations for the event, leaving it
to visual inspection or some other form of test (which
! may be a further end different method of the invention
to determine precisely where the event has token piece.
3. EVENTS WHICH CAN BE DETECTED, AND EVENT-SENSITIVE
CDNNEC710N MEANS FOR DETESTING THEM
The event which By detected in the method of the
invention can by an event which nut desired ( 8
fault) or an event which it desired. The event can be
the existence of particular condition or a change
in a single variable, e.g. nun inquiries in pressure
above a particular vnlue9 or n simultaneous or sequential
change in two or more variables, e.g. an increase in
pressure accompanied by on inquiries in temperature.
MP~B69
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The vet on be change in R variable which lasts for
only very shout time, Do a huge on 3 variable which
is maintained for Rome iamb tire. the vent can be
of any kind which director or indirectly permits or
S Swiss the current to be transmitted between the first
point nod the second point on the locating member. As
noted above, the information obtained it independent
of the i~pedancs of ho connection. Thus the connection
between toe locating and source member can be of any
ED kind, for example an electronic connection (which can
be of substantially Nero impedance or con hove substantial
impudency or on ionic connection resulting from the
presence of on electrolyte, so an inductive connection.
The change which takes piece in order to effect the
connection between the locating and source conductors
is preferably c revertible change. However 9 the
invention it ~180 useful when the change is a p~r~Qnent
one, 80 that the apparatus Utah be replaced or repaired
before the stem it operational Gwen. The system can
I be arranged 80 that it signal an event only while the
spent it taking place or 80 that it signal that on
event has occurred in the pest; in the litter case, the
8yst~m will normally be arranged By that it con be
reset.
Examples of event which can be detected include,
but are not limited to, the following.
A. The presence of water or another electrolyte which
provides sun ionic connection between exposed surfaces
of the locating sod uric members, especially when at
least part of at least one of these comprises 2 metal
core surrounded by e conductive polymer. In this cave,
the cvent-sensitive connection means can be merely c
space between the locating end source members, or it
can be e connection member on which the electrolyte
collects or Shea absorbs the electrolyte.
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. Foe existence of t~pe~ture which it below
fret temper e I or Eve a second temperature
To. In one apparatus detecting such a condition
the looting and source members are physically contacted
by a connecting member which insulates them from etch
other it To and connects them to etch other at To.
For example, it least part of the connecting member can
comprise (~) first stalely and (b) a second material
which it dispersed in the first material and which
form mobile ionic push when the temoer~ture change
from To to To. Thus the first material can be one
which change posse, e.g. melt, when the temperature
changes from I to I
In another apparatus for detecting a temperature
change, the locating and Ursa members are separated
from each Dither by a deformable insulating medium, e.g.
en insulating medium which is at least in port 8 fluid,
ego sir, end the apparatus comprises a connecting
member which change shape when the temperature changes
2û prom I to To thus forcing the member into
contact, by deforming the insulating tedium, or, if the
connecting member is itself conductive, by Forming the
connecting member through the insulting medium to
connect the members. The c~nneoting member can comprise
a heat-recoverable polymer or a heat-recoverable memory
Mets or can comprise a bimetallic trip. ohs term
memory metal is used herein to denote one of the
metal alloys (in particular various brews alloys and
nickel-titanium alloys) which exist in 8 strong gusted-
ED tic state above a transformation temperature end in weak mertensitic state below that transformation
temperature, and which, if fabricated in a first shape
in the ~ustenitic tote can be cooled to the martensitic
state and then deformed 9 wilt retain the deformed
-16~ ~2~2~
configuration until reheated to the austenitic state, when they
will revert (or attempt to revert) towards the original shape.
Where a reversible effect is desired, a particular type of memory
metal must be employed or the memory metal member can be combined
with a conventional spring metal member to produce a connecting
member which will connect the locating and source members
either when the temperature rises above the transformation them-
portray or when it falls below the transformation temperature
(as more specifically discussed below, in connection with the
Figures). For further details of memory metals and devices come
prosing them, reference may be made for example to United States
Patents Nos. 3,174,851, 3,740,839, 3,753,700, 4,036,669, 4,144,104,
4,146,392, 4,166,739 and 4,337,090.
C. A change in the concentration of a particular substance,
which may for example be a gas, a liquid or a solid dispersed in
a gas or a liquid, the locating and source members being physical-
lye contacted by a connecting member which insulates them prior
to said change, and which electrically connects them as a result
of said change. The electrical connection can for example result
from a chemical reaction between the substance and at least part
of the connecting member, thus for example releasing a mobile
ionic species. Alternatively, the presence of the substance can
for example cause at least part of the connecting member to
change shape, as for example where the substance causes swelling
of a conductive polymer connecting member or where the substance
is a solvent for an adhesive or polymeric retaining member which
maintains a spring member in a deformed state, or can change the
state of an
- MP0~69
17
I
ionization chamber or ample in e smoke detector, or
the tr~nsmissivity of photoelectric cell, which in
turn Jill cause a witch to convect the lusting end
return meter
D. A orange owe a first pressure Ply to a second
pressure, Pi, the locating and source member being
contacted by s connecting member which in~ulste~ them from
each other at pressure Pi but permits electrical con-
section Boone them it pressure Pi. For example, the
I connecting member con be deformable, e.g. composed of air
or other fluid insulting material.
E. A change in the intensity Dry other characteristic
of electromagnetic radiation, the locating and source
members being physically contacted by a connecting
member which it exposed to said reedition which
insulates them from each other prior to said change
sod which electrically connects them to each other
after said change. Suitable apparatus could for
example include photoelectric cell.
F. A change in the puritan of a valve, e.g. in a
refinery or other chemical process plant, thus changing
the putdown of witch in a connecting member between
the looting end source members.
(4? THE LIKEN, SOURCE AND RERUN MEMBERS
the locating member is preferably an elongate member,
this term being used to denote member having 8 length
which it ~ubst3ntially greater, e.g. at least 100 times
greater, often it lest 1,000 times greater, sometimes
it Lotte 10~000 times greater or even et least 100,000
time greater, than either of its other dimensions.
MP0869
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However, the locating member con also be in the form of
a sheet or eye other more complex shape.
The source member preferably ha the me general
configuration and follows the eye general path a the
locating member. Thus it it preferred that the 13catiag
and source member are elongate members which follow the
same elongate path often (but by no means necessarily)
parallel to etch other.
In many Swiss, the return member which form part
10 of the reference circuit ~180 has the some general
configuration end fly the same general path as the
locating member. This is preferred in one embodiment
of the invention in which the source sod locating
members are elongate end the return member is electric-
ally connected lo the locating member at the ends
thereof but it otherwise insulated therefrom; on thither hand it is not necessary in this embDdi~ent when
the locating and source member follow a pith in the
form of a loop Jo that the return member con be a
relstivsly short member which join (via the voltage-
measuring device the two ends of the locating member.
The return eyebrow Jill usually hollow the Game general
path foe the return end locating member in another
embodiment in which, when on event occurs, not Duly is
25. connection ode between the locating God source
members, but ~180 sun electrical connection of known
resistance is made between the return member and the
loc~tins member at the first point or at some other
point on the locating member which it further away prom
on the second point.
--19--
S256
In many cases, it is convenient for one, two or all
three of the locating, return and source members to comprise
simple conductors which have resistance but no reactance. The
locating, return and source members can be the same or different.
In order to reduce the input voltage required to provide a con-
trolled current in the test circuit, the source member can be
less resistive than the locating member. On the other hand, it
is convenient, for making splices between cables at intermediate
points, if the locating and source members to be identical In
order to ensure that the resistance of the return member it not
significant in the reference circuit, the return member can be
less resistive than the locating member. In addition, the source
or return member can be relatively large and strong (and, there-
fore, usually of low resistance, for example, less than 0.01
times the resistance of the locating member in order that the
apparatus has good physical properties. Thus in one embodiment,
the source and locating members are identical and are wrapped
around the return member which acts as the strength member of
the apparatus.
The locating member preferably has sufficient impedance
to cause a voltage drop which is easily and accurately measured.
Preferably, therefore, it has a resistance of at least 0.1 ohm/ft,
particularly at least 1 ohm/ft, eye., 1 to 5 ohm/foot. On the
other hand, its resistance should preferably not be too high and
is preferably less than 104 ohm/foot, particularly less than
102 ohm/foot, especially less than 20 ohm/foot. A key feature
of the present invention is
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that, under the condition of operation, the impedance
of the lotting eyebrow it dependent sub~t~ntielly only
on thy length thereof between toe awakened point end the
connection point. This is entoil because it it not
5 otherwise possible to calculate the location of the
convection point from the change in voltage measured by
the vDlt~ge-~esRuring device. The locating member may
be of content cros~-section long its length so that
its re~ifitance per unit length it constant sod the
voltage change it directly proportional to the distance
between the first and second point. However, this is
not essential, providing that the impedance changes in
known phony along the length of the member, 60 that
the voltage change end the distance eon be correlated.
The most common variable affecting the resistivity
(and, therefore, reaistanee) of the locating member it
temperature. Many materials, and in particular copper
and other metals most commonly used for electrical
conductors, have 8 rotate which change with
- 20 temperature to an extent which, although unimportant
for many purposes, can result in unacceptable ruins
of error in locating the first point under conditions
in which the temperature can very substantially end
unpredictably along the length of the locating member.
It is preferred, therefore, that the locating member
should have a temperature deficient of impedance
- (usually resistance) which averse less than D.003,
particularly lest than DOW, especially less then
0;00003, per degree Centigrade over at least one 25
- 30 temperature range between -100C and +50ûC, end
preferably over the temperature range 09 to Luke,
especially Dyer the temperature range Do to 20û C.
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~L225~5~
For a ~l~pl0 ~etsl condu~tDr, thy temperature coefficient
of i~lpedanoe it the slyly Eye the tg~Dp~r~ture coefficient o f
rotate, The value for opus it abut one per dog C.
Mutt Hanukkah lower temperature coefficient of resistivity
5 rye jell known sod include Cnnstantan (alto known 85
YEureka)g~Mang~nin end Cope, and others listed for example
in the International Critical Tables published 1929
by Mct;raw-~ll Dick to Vol. VI, pages 156-170.
It it of course i~portnnt that the toasting, sDuroe
nod return members should be sufficiently strung, and
should be assembled in such a way, that thicken
withstand the strews on them during in~talletiDn and
use For the return member this usually prevents no
problem, because it con be and preferably is securely
15 enclosed in a conventional polymeric insulating jacket.
However, electrical contact is Nasser at intermediate
points ox the toasting and source members, and can be
necessary it intermediate points of the return member
also. this can result in problems, particularly when
20 one or Gore of the members is a wire of relatively
small crsss-section. However, we have found that in
deny placation of the invention, e~peciclly those in
which the event is the presence of an electrolyte, on
excellent combination so desired properties can be
obtained through the use of locating member snd/nr a
member co~pri6in~ metal Gore end on elongate Scot
which electrically surrounds the core and which is
composed of conductive polymer. The term "electrically
surrounds it used herein to mean that oil electrical
paths to the sore (intermediate the ends thereof) pass
through the jacket. Normally the conductive polymer
will completely surround the core, being applied for
example by s melt-extrusion process; however it it also
possible to wake use of jacket which has alternate
insulting BectiGns end conductive section .
Jo k
-22~
The term "conductive polymer" is used herein to denote
a composition which comprises a polymeric component (e.g., a
thermoplastic or an elastomers or a mixture of two or more such
polymers and, dispersed in the polymeric component, a portico-
late conductive filler (e.g., carbon black, graphite, a metal
powder or two or more of these). Conductive polymers are well
known and are described, together with a variety of uses for
them, in for example United States Patents Nos. 2,952,761,
2,978,665, 3,243,753, 3,351,882, 3,571,777, 3,757,086, 3,793,716,
3,823,217, 3,858,144, 3,g61,029, 4,017,715, 4,072,848, 4,117,312,
4,177,446, 4,188,276, 4,237,441, 4,242,573, 4,246,468, 4,250,400,
4,255,698, 4,271,350, 4,272,471, 4,304,987, 4,309,596, 4,309,597,
4,314,230, 4,315,237, 4,317,027, 4,318,881 and 4,330,704;
J. Applied Polymer Silence 19 813-815 (1975), Klason and Cubit;
Polymer Engineering and Science 18, 649-653 (1978), Narkis et at.
The resistivity of conductive polymers usually changes
with temperature at a rate well above the preferred temperature
coefficient of resistivity set out above, and the PTC conductive
polymers often increase in resistivity by a factor of 10 or
more over a 100C range. Accordingly, it is important that in a
locating member comprising a conductive polymer jacket, at all
temperatures likely to be encountered, e.g., at all temperatures
from 0 to 100C, each longitudinal section of the conductive
polymer jacket has a resistance which is at least 100 times,
I'
-23- I So
preferably at least 1000 times the resistance of the core of
that longitudinal section. In this way (since the core and the
jacket are connected in parallel), the jacket does not make
any substantial contribution to the resistance of the elongate
conductor, and any change in its resistance with temperature
is unimportant.
The second point on the locating member must have a
known location, and it is normally a fixed point. When the soys-
them is designed to detect different types of events occurring
independently, the second point is preferably the same fixed
point for detection of the different events. In the case of
an elongate locating member, the second point will normally be
at one end or the other of the locating member. However, the
invention includes, for example, the simultaneous or sequential
use of a plurality of second points to determine the locations
of a plurality of first points when a number of different events
having identified a number of first points.
MP0~6g
-24-
1225~S~;
SUPPLY
he runt Rich it tr~n~itted eighteen the first
on second points must be of known it end I preferably
supplied by 8 controlled current source, e.g. a galvano-
stat; however, a controlled voltage Ursa can be used providing that a ~urrent-me~suring device it included
in the apiarist 80 that the location of the first
point eon be calculated. the current may be a direct
current or an alternating current of regular sinusoidal
or Dither for. The current which flows between the
first and second point it preferably in the range of
0.05 to 100 millismp~, particularly Owl to 10 milliamps,
ego Do to 3 milliamps. The controlled current source
it preferably a fixed current source or 8 current
source which ran be adjusted to a desired end known
value, for example in obtain improved accuracy in
locating a fault which was detected at a lower current
level However, it it Ahab possible to Us a Fixed
voltage source, in combination with a current-meacuring
device which measures the current flowing between tile
first and second points. The power source is preferably
- connected to the-locating member at the second point at
all times and, in the absence of an event, it otherwise
insulated from the locating member.
(6) THE VOL~AGE-MEASURING DEVICE
the voltage-~easur~ng device can be of any kind,
and suitable device sure well known to those skilled in
the art. Preferably the voltage-mea6uring device is
voltmeter which ha resistance of it least Lowe Dims,
ED preferably it least l megohms specially at lest lo
megohms .
Mpoa6g
-25-
- Lowe:;
I PMYS~CAL AND ELE~TRlCAL RELA~lnNSHIPS BETWEEN THE
LD~rD~INl5 DO THY PYRITES
A briefly indicated in the description of Figure 1,
the physical and electrical relationships between the
cùmpsnents of the apparatus of the invention can be
widely varied. Figure 2-24 show 8 number of different
arrangements which pacific example of the circuit
generically illustrated in Figure 1 and of various
preferred embodiments of the invention. In each of
Figures 2-24~ there it power source 15, a voltage-
measuring device 14, locating member 11, a source member 12 and a return member 16. The locating member
it shown I resistor Buick it must hove appreciable
rustiness in order for the voltage drop down it to be
large enough to permit accurate location of the point
1, at which the source member it connected to the
locating member The source and return member are
shown a simple low rustiness conductors, which they
preferably are, but the source member can have high
and/or indeterminate resistance (providing that the
ED power source con drive a known current between points 1
: end 2) end the return member con hove 6ubstsntial
resistance, providing that it it e known resistance.
The connection E, El, En end I are Winnie pa
resistor if they Form port of the text circuit, since
I the invention permits these connection to be of
indeterminate sod high resistance (though of course
they eon be of substantially zero resistance or of
substantial end known rustiness On the Dither hand,
these connections ore shown a simple conductor if
they form part of the reference circuit, wince the
invention requires that these connection are of known,
end preferably smell, resistance. In a number of the
Figures, there rip shown witches, I 51 and 52
MP0669
-26-
~Z25;~5~
An otter ennui con be employed, in eddit~on to simple
switches awaken 2~3'D resist~ncoe eleet~onir contact,
in the eta erupt, undo en other jeans p~o~idiny a
eonnectiun of known resi~tanre run be used in the
reference circuit. In most of Figure 2-24, the purer
source is shown 88 8 controlled current ours but in
Figure 3, the power source to a battery sod the test
circuit includes an Peter 154; and in Figure 4 the
power source it z controlled voltage AC source sod the
test oirc~it again include an ammeter 154.
Some of the different possible relationships
between the components will now be enumerated,
using Figures 2-24 en examples of these relstion6hips.
(1) The power source can ye pow toned neon the second
point on the locating member, as illustrated in Figures
. 2-7 and 12-22, or near the end of the locating member
which it remote from the second point, as illustrated
in Figure B-9. In most case, the power source end
the voltage-meusuring device Rye positioned near to
each other en illustrated on Figure 2-5 and 7-22.
I A shown for example in Figure 10~ the rJppsratus
eon include one or Gore witches which my be ganged
together or Jay operate independently, to provide for
witching the connection between the locating member
and the power source from s first ~rr3ngement in which
the second point is it one end of the locating member
us shown in Figure 2, to D second arrangement in which
the second point it sty the opposite end of the locating
member, as shown in Figure 9 9 thus mewing it possible
first to measure the distance from one end the an
event has token piece sod then to measure the Dayton
from the other end the on event his taken place.
MP0869,
-27- ~225256
(3) it it nl80 ~585i~1e for the playwright to be
one on which Dennis Or thy event kiwi nut only
connection eighteen the source end lotting mummer, but
~180 continue between the return sod locating
embryo, A shown for example in Figures 5, 7, lo and
20. Such a system can be valuable for example in
providing 8 cut-to-length apparatus. The making of the
oonneotion between the looting end return member con
be the direct result of the making of the connection
10 between the lotting end source members, e.g. by means
of c ganged witch, or the condition which causes one
Connection to be made gun also cause the other connection
to be ode. The e two possibilities ore shown in
Figure 5. Alternatively, the connection between the
toasting member can result from the existence of a
condition which it different from the condition whir
effects connection between the locating end source
emeries. This possibility it one in Figures 7, 19
on ED.
(4) It it at o possible, as one for example in
Figure 11, for the apparatus to include one or more
witches, which may ye ganged together or my operate
separately, Jo that the pretty am be converted into
on electrical system illustrated in Figure 12, in
which
(a) on electrical current is driven down the
whole length of the locating member ox
the power source
by the return member it electrically connected
I to the second point on the locating member
through the voltage-measuring device, and
it otherwise insulted from the locating
member, on
MPOB69
I
~LZ;~5~56
(c3 then 8 second and different type of event
I onnec~ion of known impedance it
ode between the loc~t.in~ eyebrow end the
return eyebrow, thus creating n reference
circuit which comprises a voltage- measuring
device, those port of the toasting member
and return member which lie between the first
end second points end the connection of
known impedance, the voltage-me~suring device
hiving B known impedance which it very high
by comparison with any unknown part of the
impedance of the other component of the
reference circuit.
(5) As shown for example in Figure 13~ the event con
comprise the existence of particular condition at
etch of c plurality of sp~ced-spart 1DCatiOn87 the
connection between the locating member end the source
member being made through on event-sen~itive connection
member comprising a plurality of condition-sens~tive
embryo which are eletricelly connected in series,
which sure re6pectaYely located et each of rid spaced-
part locat~Dns, and each of which is electrically
conductive when said condition exits it its location
and it not electrically ~onductivle when slid condition
does not exist it it location.
(6) As shown for example in Figure 14, the event can .
ccmpri%e the existence of particular condition it it
I~sst one of a plurality of ~psced-spsrt location6,-the
connection between the toasting member and the source
member being sue through an event-sen~itive connection
member comprising plurality of condition-3ensitive
members which ore electrically connected in parallel,
MP0869
-29-
~22~Z5~
which err respectively located at etch of said spaced-
part locations, end Shea of which it electrically
conductive when said condition exits it its vocation
end it not electrically conduct when rid condition
does not exist it it location.
(7) As one for example in Figure 15, the event can
comprise the existence of a first condition at a first
locution an the existence of a ~ecsnd condition it a
second location (which may be lmmedistely edj~cent the
first location) 9 the connection between the locating
member end the source member being made through sun
event-sensitive member comprising (a) a fir~t-condition-
sensitive member which it it the first locution end
which is electrically conductive when the first condition
exist it the final location and is not electrically
conductive when the first condition does not exist at
the first location and (b) a ~econd-condition-sen itive
member which it it the second location 9 which it
electrically conductive when the second condition
2G exits at the second locution end it not electrically
conductive when the second condition does not exist at
the equine location, and which it electrically connected
in series with the fir~t-condition-sensitive member.
(B) As shown for example in Figure 16, the event con
I comprise the existence of a first condition at first
location or the existence no a second condition at 8
second luxation (which may be immediately adjacent the
first location), the connection between the locating
member and the source member being mode through on
event-sen~itive member comprising (a) a fir~t-condition-
sensitive member which as at the first locution end
which it electrically conductive when the first condition
MP0~69
--30-
~225ZS~
exists at the first locution end it not electrically
conductive when the first condition dyes not exist it the
First losatiDn and by a ~econd-condition-~en~tive member
which it sty the second l~catiun, which it electrically
conduit when the second condition exit at the
second location sod is not electrically conductive when
the second condition does not exit it the second
location, and which is electrically connected in parallel
with the fis~t-condit~on-sensitive member.
~93 It ill sly possible, as shown for example in
Figure 17, for the system to include two or more source
member , which become respectively connected to the
locating member when particular condition (different
for etch source member) exit. In this cave the event
15 it the sxi~tence of one of those two (or more) conditions
at any point long the elongate path followed by the
locating end source members. The system con also
include switches, e.g. as shown in Figure 17, such that
it it possible to disconnect ~11 but one of the source
ED members, and thus to determine which of the particular
conditions exits.
- (lo) It it also pc8~ible, I shown for ample in
figure 18, for the system to include at least one
auxiliary source member which is connected to the
25 power source end which become connected to the source
member (or to another auxiliary source member) when a
particular second condition exit, the equine condition
being different from the first condition which causes
the Ursa member to become connected to the locating
member. In this case, the svçnt it the existence, at
en one or more points along the path, of a second
condition which kiwi the exhaler source member to
become connected to the source member, and the
b20 MP0869
. -31-
~22~
existence, et one or dry point along the pith, of
fist edition ho KIWI the Doris end locating
eyebrow 5 to become connected .
ill) It it Allah possible, a shown for example in
Figure 19 end 20 for the system to include it least
one auxiliary return member which is connected to the
voltage-oes~uriny device and which becomes connected to
the Saturn member when a second condition exifits, the
second condition being different from the first condition
which ceases the source and locating embryo to become
connected. the return member con be connected to the
end of the lccating;member which is remote from the
second point ox illu6trsted in Figure 19, in which
essay the event is the existence of the first condition
at one or more points long the pith end the existence
of the second condition at one or more point along the
path, with the information provided being the locution
of the final condition which it nearest to the second
point. Alternatively, 98 illustrated in Figure I the
I return member con become connected to the locating
somber as the result of third condition.
(12) It is also possible, as shown for example in
Figure 21, for the apparatus to follow sun elongate path
on the form of loop ED that the return member need
not follow the elongate pith but con amply join, Vim
the volt~ge-measurin~ device, the WOODY ends of the
toasting member.
(13) It it else possible, as shown for example in
Figure 22, for a plurality of event-detecting stations
(which can detect the same or different event) to be
positioned at location which are remote from the
by 1 MPDB69
--32-
5~5~
toasting member end to be electrically (or otherwise)
connected to witches (ego e~ctromagneticolly Operated
relays between the Latin end source members.
(14) It it alto possible, no shown for example in
Figure 24, when event-detection is required only in
6paced-apert zone, for the locating member to comprise
(o) plurality of spaced-apart elongate looting
component (AYE, 114~, 114C and 114D in jig. 23), etch
of which provides a series of points to which the
connection eon be made end preferably has a relatively
high resistance per unit length, end (b) plurality of
spaced-ap~rt elongate intermediate component (AYE
1158, end 115C in ire 23) which foxily separate
sod electrically connect the locating components 9 which
cannot become directly connected to the source member
and which preferably have 8 relatively low resistance.
. This system might be used for example when detection
end location woe needed within etch of a playwright of
houses separated from each other long a street, but
ED not between the hues
( 15) Toe method can also be used to locate event along
a branched pith as illustrated in Figure 24. However,
when using such a branched 8y8tem, if the voltage-
Treasuring device ooze On event at Q di~tcnce beyond
25. the irrupt broaching punt then there are often two or
more possible locations for the fault. It desired, the
locution eon be precisely identified by connecting the
controlled current source and voltmeter to the conductors
et the branch punt) (preferably via low rustiness
drop lends ~natnlled it the same time as the detection
system). this expedient con alto be used in unbranched
systems in order to provide improved accuracy of locution
MPDB69
~33-
issue
of the en after the general vicinity Do the event
has teen inducted Alternatively AC current source
of different frequencies eon be o~ployed sequentially
and f Lowry con be placed in the different branches Jo
S that only one ranch is being tested sty en one time.
By VOLTAGE DROP VS. DISTANCE
., , _.
The relationship between the voltage drop myriad
by thy vDltsge-~ea~uring device undo the distance
between the first and second points will depend on the
10 yo-yo in which the apparatus is designed. When connection
can be made to the locating member at any point along
it length, end the locating member it of uniform
impedance along its length, then the relationship will
be a straight line of uniform pow as illu~trsted in
Figure 25. When the event-3ensitive connection means
. is discontinuous, 80 that connection to the locating
member Sybil only at spaced-apart punt then
the relationship will be a eerie of Taipei en shown in
figure 26. when the locating member it divided into
JO locating and connection zones and son be contacted at
; any point-~ithin e locating zone, as shown in Figure
23, then the relationship it as shown in Figure 27.
(9) PARTICULAR EVENT-SENSITIV~ CONNECTION MEANS
Figure 28-33 show cross-sections through apparatus
of. the invention. In figures 28 end 29, the apparatus
includes a source member having a metal core 121 end a
conductive polymer coating 122; a locating member
hiving a core 111 which is composed of a metal whose
receptivity it substantially invariant with temperature
and e conductive polymer coating 112; and 8 return
member 16 which is composed of motel and it unrounded
by a polymeric ~n~ulat~ng kowtow 161.
MPOB69
-34-
I So
In ire I n pyrrhic insulting connecting
member I hiving concave traces lies between the
source and locating en no thy component
sure joined tsgethe~ my on perjured end therefore
5 liquid-permeeble, undulating jacket 91. So long as
there it no electrolyte around the apparatus shown in
Figure 29, there it no electrical connection between
the locating and ooze members. However if the
apart is exposed to an electrolyte) on ionic
I connection it cede Steen the locating end source
emboss.
In Figure 29, member 21 lie between the
locating and source member, and the components
are surrounded by an insulating jacket 92. Under
normal conditions, the member 21 prevents electrical
contact between the locating and source member&,
. but the member 21 consists of or contain a material
which becomes an electrical conductor when an event
occurs. For example, the member 21 can comprise an
organic polymer foam which is impregnated with
material which forms mobile ionic specie Yen the foam
structure it dsmaged9 fur example by En event involving
excessive pressure transmitted through a flexible
jacket I or an event involving excessive temperature
which Casey the form to melt, or an event involving
the presence of chemical which can penetrate the
kowtow 92 (which may be portrayed for this purpose end
which resect with the foamed member. The member 21
can also be composed of a material which becomes
ED conductive when it it COmpreB8ed.
Referring now to Figure 3û, this it 8 CrD~S-SeCtion
through apparatus for detecting en over-temperature
fault condition. Locating member if and source in ember
MP0869
~35~ I 2 or 6
I
I are to strips graced pretty by insulting trips
ED, defining on a I between thy rondu~torfi.
Return Burr It nod nutting bucket 161 rounding
it Ore alto present. A bimetallic C-clip comprising
ethyl strip 7 and 8 bear on the center portions of
the troupe no 12 through insulating pad 78; under
normal conditions the clip it in the open position
one, but it it BY con~trlleted and arranged that if
the temperature essayed p~rticulsr value, the clip
closes and brings the strips 11 end 12 into electrical
contact Suitable C-clips con be oDmpo~ed of e spring
- steel member and a memory metal member. For example,
if under normal countdowns; the inner member 7 to
composed of spring steel 9 end the outer member B is
15 composed of a memory metal in the marten~itic phase end
it maintained in an expanded configuration by the
member 7, then if the temperature reaches the trsnsfor-
ration temperature of the memory metal, the member B
Jill recover, overcoming the elastic rustiness of the
member 7 and bringing the strip no 12 into contact.
Figure 31 it somewhat similar to Figure ED, but
make U88 of b~me~llic member to bring a strip 12
sod 8 wire 11 into electrical contact if the temperature
f8118 below a preschooler level. Strip 12 it connected
to C-cl~p having an inner member 7 composed of spring
steel on outer member 8 composed of 3 memory ~etsl.
the Kelp it separated from wire 11 by an sir gap 21
in an aperture insulting member 20. Under normal
conditiDns9 the Emory petal member 8 it in the eighteen-
ED tic state end Montanans the spring steel member 7 incompre~sed configuration 80 that there 8 no c~ntsct
between strip 12 and wit no 11. If the temperature S~rClp8
below the trsn~for~atiDn temperature of the memory
MP~B69
_36-
~225~5~
eye hut converting the member into the weak
~erten~sc tote the spring await eyebrow oxp~nd~
end equity electrical ~nn~ctio~ button the trip 12
nod the wiry 11.
In Figures 30 no 31, the member will generally
Cooper a plurality of discrete, sp~ced~p~rt, members
However, 8 ~nti~uou~ Member Jill also be satisf~tory.
figures 32 sod 33 show apart for detecting en
increase in pressure, for example for placing under a
10 floor covering us burglar lam The source member
- 12 it in the form ox- e metal trip end is surrounded by
on insulating polymeric sheet 22 which has portray
21 in itfi top surface. the locating member if it a
constant resistance metal wire which it separated from
the member 12 by insulting sheet 22 end crosses
over the portray 21. The return member 16 it placed
below the second conductor end it insulted therefrom
at 811 points. A flexible insulating polymeric jacket
92 surrounds the vsriou~ component. Under normal
I conditions the locating end source members sure not
- electrically connected. However, if the pressure on
the top surface D f the insulting jacket incrP~ses
~ufficiently9 the locating member I forced through
aperture 21 to contact the source member.
I The invention it illustrated by the following
Examples:
MP0~69
22~ii25
eta one in figure 2 was prepared. The
controller current source eye a gslvanostet Thea a
oompli~nce voltage of lo volt end produced e controlled
current of 0.001 imp. The voltmeter had an input
l~peda~ce of 1 ego and full scale reading of 200 my
the Ursa ember was a 3û A copper wire which way
surrounded by a ~elt-extruded jacket of conductive
polymer condition the kowtow was about 0.04 inch
thick. ho conductive polymer ccmpo~ition ho
resistivity of about 3 ohm.cm sty 25C end comprised
carbon black (about I pretty by weight) dispersed in
thermoplastic rubber which it told under the trade name
PRY end which it believed to be 9 blend Do polyp
propylene and an ethylene/propylene rubber stout 55
parts by weight). The locating member was the me a
the firs except that 30 AWN C~nstanten wire way used
instead ox the copper wire. The resistance of the .
second conductor was 2.940 ohms foot The return
member Wow 12 AWN copper wire end it Wow 8UrrDUnded
by polymeric insulating jacket.
In a number of tots a damp sponge we placed
on toe locate and Doris member lo effect elect-
rival connection between them, the member being
dried between the tests. It was found that, as
expected from theory, the distance (d) in feet to the
damp ~p3nge could be c~lculsted from the equation
V
d = 0.001 x I
where Y I top voltage (in volt) recorded by the
ED voltmeter. The discrepancy between the actual end
cslculsted value Do d we let than D. lo .
or k
. .
MP0869
-3B-
~5Z5~;
R trait one in figure 2 wow prepared) using
a gelv~nDatat and voltmeter pa specified in example l.
An apparatus somewhat similar in operation to that
shown in Figure 33 sod 34 WAS prepared us fulled.
To provide the source member, a strip of copper foil
way tuck to the interior bottom surface of a tube of
Roy inked palyvinylidene fluoride. To provide the
tying umber, 30 AWN ConstQntan wire aye secured
to the interior top surface of the polyvinylidene
fluoride tube, diametrically opposite the copper
strip 3 the wire being woven through the tube at
interval ED the it was maintained substantially in
contact with the tube throughput its length. The
return member Way a 30 AGO insulated topper wire.
In a number of sty pressure way exerted on the
top surface Do the tube it a location separated from
the near end. the tube deformed elastically, bringing
the locating and source members Pinto contact, and
resulting in a reading on the voltmeter from which the
location of the pressure point elude be calculated.
