CA1063176A - Sensing electrical parameters inside conductors - Google Patents
Sensing electrical parameters inside conductorsInfo
- Publication number
- CA1063176A CA1063176A CA247,145A CA247145A CA1063176A CA 1063176 A CA1063176 A CA 1063176A CA 247145 A CA247145 A CA 247145A CA 1063176 A CA1063176 A CA 1063176A
- Authority
- CA
- Canada
- Prior art keywords
- conductor
- voltage
- hollow conductor
- display
- hollow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/142—Arrangements for simultaneous measurements of several parameters employing techniques covered by groups G01R15/14 - G01R15/26
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/58—Testing of lines, cables or conductors
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Parameters associated with a bus, which may be either an unshielded hollow conductor or a shielded hollow conductor, may be difficult to determine when the bus is carry-ing large currents at high voltages. An indicator carrying a display is mounted internally to be visible through a window and thereby avoid conductors running from a high voltage region to an external place. Thus temperature of the bus can be determined within the hollow conductor and can be used to activate a display adjacent an opening or window in the conduc-tor. The display may be powered by a power supply mounted within the hollow conductor with the power supply deriving a voltage from longitudinally spaced points on the inner surface of the hollow conductor. The current in the hollow conductor may be determined by measuring the IR drop between spaced points on the inner surface of the conductor, measuring the operating temperature of the conductor, determining the resistance from the measured temperature and the temperature/
resistance characteristic, and using the resistance and IR
drop to determine current. Similarly the IX drop can be determined by using a loop enclosing a longitudinally extending portion of the hollow conductor, and this in turn can be used to determine reactance if the current is known.
Parameters associated with a bus, which may be either an unshielded hollow conductor or a shielded hollow conductor, may be difficult to determine when the bus is carry-ing large currents at high voltages. An indicator carrying a display is mounted internally to be visible through a window and thereby avoid conductors running from a high voltage region to an external place. Thus temperature of the bus can be determined within the hollow conductor and can be used to activate a display adjacent an opening or window in the conduc-tor. The display may be powered by a power supply mounted within the hollow conductor with the power supply deriving a voltage from longitudinally spaced points on the inner surface of the hollow conductor. The current in the hollow conductor may be determined by measuring the IR drop between spaced points on the inner surface of the conductor, measuring the operating temperature of the conductor, determining the resistance from the measured temperature and the temperature/
resistance characteristic, and using the resistance and IR
drop to determine current. Similarly the IX drop can be determined by using a loop enclosing a longitudinally extending portion of the hollow conductor, and this in turn can be used to determine reactance if the current is known.
Description
L7~i :
This invention relates to the determination of electrical parameters and other parameters in an electrical bus.
For the purpose of this description, electrical bus may be considered to include a hollow conductor or bus which is not shielded along its length and a metal enclosed `; ?
bus having a hollow central conductor and a surrounding metal enclosure. The central conductor is supported within the metal enclosure by insulators. It is usual to operate the unshielded bus at lower potentials to carry currents of a large magnitude. For example, an unshielded bus might operate at a potential of perhaps 1000 to 5000 volts and `~
could carry currents of the order of a few thousand amperes.
It is usual to use metal enclosed bus at higher potentials where the metal enclosure is grounded and ofEers protection for the central conductor. For example, a metal enclosed bus might operate at a higher voltage, perhaps of the order of 20 kilovolts (kV) to 230 kV or higher and may carry currents of 5000 to 50 000 amperes or more. ~-In recent years with the trend to higher voltage, the ``
metal enclosed bus has seen considerable use for conducting -electric current for power transmission and distribution.
It is particularly useful at power generating stations where ;~
large amounts of power must be handled. It may contain an insulating gas, particularly at higher voltages. It may have means for circulating a gas within the metal enclosure ;~
for cooling purposes when large amounts of power are being handled. The present invention is suitable for determining parameters in such metal enclosed bus, although it may also be used to determine parameters in unshielded bus.
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~063~7~ CASE 2397 Paxameters which may be of interest in the operation or use of an electrical bus include: current I in the bus~
the temperature of the bus, the IR drop where R is t~e resistance of the bus between two longitudinally spaced points. IZ drop where Z is the impedance of the bus between two longitudinally spaced points, (IZ drop has been determined or bus in the prior art)~IX drop where X is the reactance of the bus between two longitudinally spaced ~;
points~ and the parameters R, X and Z themselves, No simple means has been devised in the past to determine some of these parameters with a desired accuracy. While values for IZ drop have been determined in the past, it has in itself not been of great practical value~ There have been a number of attempts made to determine aurrent and to determine temperature and perhaps ~ther parameters, It i8~ however~ quite dif~icult to determine parameters in a ragion of high voltage stxess and to conduct the signal representing the parameter Erom that region, ~ot only do the high voltages cause problems7 but the large currents cause heating and create magnetic fields which can in-terfere with a determination o~ various parameters, For example, it i5 ~uite common to obtain a temperature indicat~on on a metal enc~osed bus by affixing temperature `-sensitive patches to the outer surface of the centxa~
conductor where the patches are visible ~rom inspection windows. The patche~ change colour at specific temperatures~
This provides a very cheap way o~ determining if a specific temperature is exceeded~ }t is however unsatisfactory in that each patch provides an indication of ona temperature only For another example, it is known in an unshielded bus to have a current transformer surrounding the bus and ~;3i7~ ;
insulated therefrom to obtain an indication of current.
Such current trans~ormers are expen~ive and bulky and are inconvenient to use, particularly when high voltages are involved and the leads must be run from a high voltage region to a remote r~gion. m is type of arrangement has also been used with metal enclosed bus to obtain a current reading. The current transformar is in this arrangement mounted on an insulating bushing surrounding the central conductor and within the metal enclosura. The ~econdary -leads from the current transformer were usually passed to the outside of the metal enclo3ure throuyh a ring arrange-ment. Metal enclosed bus i5 usually designed ~or higher voltages and the voltage gradient between the central conductor and the me~al enclo~ure is usually large. A
current transformer is normally operated at ground potential ; and it is difficult to prevent flashovor and corona problems when a relatively bulky trans~ormer at ground potential is inserted into a bus where there is a large voltage gradient. --In addition, as the bus and enclosure are normally welded together w~en installed, it is difficult to inspect or repair such a current trans~ormer~
~nother prior ar~ arrangement avoids the pxoblem o~
having a current transformer within the metal enclosure of a metal enclosed bus. In this arrang~ment a gap is provided in the metal enclosure and the gap contains in~
v sulation. A conductor member capable of carrying large currents joins the adjacent ends of ~he metal enclosure extending externally over the insulation to ~orm a small loop. A current transformer is positioned over this loop which carries the current in the enclosure o~ a phase in the system. This current is substantially e~ual and opposite to the current in the central conductor and con-.~ .
_ 3 .'~ .
~6317~
sequently gives a xepresentation of the current in the ~entral conductor EIowever this arrangement requires a break or gap in the metal enclosure wherever a current reading is desired and this break must not only contain insulation but must be sealed in cases w~ere insulating B 9ga~ is contained within the metal enclosure. In addition, the metal enclosure may be subjected to ~luctuations of current from stxay fields originating externally where the central conductor would be shielded from such fluctuations.
Also, arrangements of this nature are relatively expensive.
It is, of course, desirable to obtain a reading of current in a bus as accurately and a~ economically as possible. Because o~ the large currents normally handled, small percentage errors can involve considerable amount~
of power. It is also desirable to measure or determine the IR drop in a bus during operation so that the re-sistive losses will be known. ~here have been a number o~ ways proposed to do this, but none appear to have had ;
the desired accuracy or simplicity~ Similarly, it is desirable to know the IX drop to have a complete under-standing o~ the system, and it appears there have been no prior art arrangements which give the desired accuracy and simplicity~
In addition it is desirable to know temperatures at i various places on a buso For example, in an unshielded bus it may be desirabla to know the temperature of the bus itself. In a metal enclosed bus it may be desirable to know the temperature not only of the bus or central conductor but perhaps within the central conductor or adjacent the central conductor. It is difficult to determine temperature because the temperature semsitive elements normally provide output voltages as signals _ 4 ~;3176 ;;
which represent temperature. These voltages are many orders smaller than the voltage gradient surrounding the central conductor. Small extraneous voltages might ;~-be picked up by the wires and affect the accuracy of the temperature indication. Also, the wires which carry the signals from the sensor would normally be at ground poten-tial. It is not desirable to have wires at ground potential extending through a large voltage gradient. Various ways have been proposed to overcome these problems,~for ;~
example by using a high frequency carrier signal to carry the temperature signal as a modulation of the carrier. ~, None of these have been completely satisfactory.
It has been discovered that an accurate determination can be made of various parameters of an operating bus by making these determinations in a specific manner and by making the determined values available externally without causing deterioration of the accuracy. ;
It has been found that by obtaining a voltage reading from longitudinally spaced points within an unshielded bus or within the central conductor of a metal enclosed bus, an accurate determination can be made of IR drop, `
where R is the resistance of the conductor between the points of measurement. It has been found that by obtain- ;
ing a voltage reading from a loop extending within the conductor of an unshielded bus or within the central conductor of a metal enclosed bus for a predetermined length, then brought outside the conductor and extended to form the loop, an accurate determination can be made at a ;
break in the loop for the IX drop where X is the reactance of the portion within the loop.
In an unshielded bus operating at lower voltages it may be feasible to bring the signals representing t:he ~' ', ' `"'.' ` ' ' ''': . ' '' , :
C~SE 2397 ~
~C~63176 paxameter externally on a twisted pair o~ wire~ without degrading the accuracy~ In a metal enclosad bu~ in accordance with the invention, values determined within the metal enclosure are made available externally by pro~iding a power supply and a visual display. ~or example, for values such as IR drop, t~mperature, or current det-ermined within tha central conductor, Zl display is positioned wnthin the central conductor to be visible through aligned openings in the central conductox and enclosure~ The opening in the central conductor is preferably covered with a Farraday screen and the opening in the metal enclosure is sealed with a transparent window. A power supply provides power to operate the display, and if required ma~ also provide power to the temperature sensor or other sensor~ In a preferred ~orm the power ~upply obtains its energizing voltage ~rom a voltage drop between longitud~nally spaced point~ on the inside of the centxal ;~
conductor using leads extending within the conductor to the lon~itudinally spaced points. A power supply could - 20 be energized by IX drop or IZ drop but, while the voltages `~
might be greater, thîs i8 not pre~erred. Transients are ;;
generally reactive in nature and related to frequency and would appear in a voltage for energiæing or powering a power supply ~rom IX or IZ drop~ It is thereore pre-ferred to powar the supply using IR drop which is sub-stantially ~ree o~ transients. It is also possible to have a supply using batteries~ In low voltage systems only, an external or remote power ~upply is ~easible.
Similarly9 for determining IX drop9 the voltage drop is normally determined adjacent the outer surface and the display w~uld also be adjacent the outer sur~ace It will be apparent that the loop could be broken wi1:hin : .
10~317~ C~SE 2397 the conductor and the di~play would then be within the conductor also Placing ~he di~play wi~hin the conductor would9 o~ course, avoid problem~ which might occur with a display in the high voltage gradient outside~ If a power supply i5 used to power the display9 ~t is desir-able to have the supply inside the hollow ~onductor whether the display is outside or inside The supply can thus be energized by IR drop~
m e temperature may be determined by usin~ a tem- -perature sensitive element or t~mpsrature sensor a~fixed .
to the main conductor or other place where a temperature determination is required. For example, the temperature `c: ;
~ensor could be ixed to thi~ inner surace o~ the hollow ~:
main bu~ ox conductor. A display means, and a power supply to provide power ~ox the display means, are within the conductor so that the display on the display means can be :
seen through a window or opening in the conductor. The power supply may be as previously mentioned~ energized by the IR drop between spaced points on the conductorO
The temperature sensor actuates the display to provide an indiaation of temperature~
m e invention al80 includes a determination of para-meters related to the metal enclosure of a metal enclosed bus. m e ~ame arrangement will provide a determination o~ IR drop, and IX drop and~knowing R or X9 the current may be determined~ The IR drop is determined using long-itudinally spaced points within the metal enclosure~ and ;~
the IX drop is determined using a loop extending in~
ternally and externally of a portion of the metal enclosure~ -If desired IZ dxop may also be determined as i~3 known in the prior art by u~ing longitudinally sp2lced points on the metal enclosure9 externally of the~ en~
closure.
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us, according ko one form of the invention there is providad a method for determining the IR drop in a .
hollow conductor for carrying a large current where I
is the current in the hollow conductor and R is the resistance in the hollow conductor between a irst and a seeond point spaced longitudinally on the conductor, compri~ing obtaining a voltage representation internally o said hollow conductor between irst and second ter-minal points within said eonductor on the inner sux~ace thereof correspo~ding to said ~irst and second pOilltS
r2spectively, displaying the voltage representation obtained on a display means within said conductor; said display being a determination o~ IR drop, and providing opening means to ma~e the displa~ vlsible externally~
According to another ~orm of the invention there is provided a method for determining the IX drop in a hollow conductor for carrying a large current where I is the ` .
current in the hollow conductor and X is the reactance o~ the hollow conductor between a ~irst and a ~econd point spaced longitudinally on the hollow conductor, com- .. .
prising providing a conductor in the orm of a loop ex-tending internally o said hollow conductor between said first and second points, extending through the w~lls of said hollow conductor at said first and second points . and extending externally to form the loop~ displaying the ; voltage representation obtained on a display means, said display being a determination o~ IX dropg and making : ~aid display visible at a region removed rom sai.d con_ ;:
du~tor :
According to another form of ~he invention there is provided a method for determining tempera$ure o~ a hollow aonductor or carrying a large current9 comprising plaeing . ~ .
_ 8 -~063176 CASE 23~7 a temperature sensor on the surface of said hollow conductor, connecting said temperature sensor with a ; .-: display means adjacent said hollow conductor to display a representation of temperature detexmined~ and making said display visible at a region removed from said hollow conductor~
According to another form of the invention there is provided a mekhod for determining current I in a hollow conductor for carrying a large current, comprising, ``
obtaining a voltage representation V internally o said :~
hollow conductor between a first ~nd a second terminal point on the inner surfaca of said hollow conductor, .:.
obtaining an indication of temperature ~rom a temperature sensor mounted on the inner surace o~ the wa.ll o~ said hollow conductor, determining the resistance R o~ said hollow conductor from the temperature resistance relation_ ship for said hollow conductor and the temperature from ~-:
the sensor, ~or that portion of the hollow conductor between said first and second terminal points~ determin_ ing the current I from the voltage representation V
where V ~ I R~ and displaying the determined value ~or ~.
the cuxrent I~ :;
According to another form of the invention there is provided apparatus for determining the IR drop in a hollow conductor for carrying a large current, where I is ~:
the current in the hollow conductor and R is the resis-tance of the hollow conductor betwe~n a first and a ~-second point spaced longitudinall on said hollow conductor;
comprising display means mounted within said hollow con~
ductor to the wall of said hollow conductor, said hollow conductor having an opening in said wall~ the edges of said opening defining a viewing opening for viewi~y the _ 9 _ : .
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10~3176 CASB 2397 display means externally of said hollow conductor, a voltage detector means mounted within said hollow con-ductox, first and second terminal points on the inner surface o~ said wall of said hollow conductor at said irst and second points respectively, input conductors extending within said hollow conductor and co~necting ~ ~:
each of said first and second terminal points to said voltage de~ector means to provide at said voltage det-e~*or means a voltage representative of IR drop between ~ ;:
said irst and second points, said voltage detector means providing a voltage signal representative of said :CR :
drop between said first and second points, and means ; connecting said voltage detector means and said display means to apply said voltage signal to said displa~ means and actuake said display means respon~ive thereto to display an indication o~ IR dxop According to another ~orm of the invention there is provided apparatus for determining the current } in a - :
hollow conductor having a wall for carrying a large :
current, said wall having a viewing opening therethrough, comprising a voltage detector means mounted within said ~`
hollow conductor, ~irst and se~ond terminal points on the inner sur~ace o~ sa~d wall ~orming said hollow conductor spaced longitudinally on said conductor, input :
conductors extending within said hollow conductor con~
necting said first and second terminal points to said voltage detector to provide a voltage at said voltage detector representing the IR drop between said first ~nd second terminal points~ where R is the resistance of said hollow conductor between said ~rst and second ~ :~
terminal points9 said voltage between means providing a ~ :
voltage signal representing said IR drop9 a temperature sensor mountsd within said hollow conduc~or to the wall _ 10 -, -~'~ . : . . . ' .
~ 1063176 CASE 2397 : ofsaid h~llow conductor to obtaln a signal representing the temperature o~ said hollow conductor, means connecting said voltage sensor to said voltage detector to apply .~ thereto said signal repre~enting the t~mperatur~ o~ said conductor, means in said voltage detector means responsive to said temperature signal to provide a signal represent_ . ing resistance R based on the tempexature/resistance -~
: relationship of said hollow conductor current determining means connected to said voltage detector means to receive ~ :
said signal representing resi~tance R and said voltage -signal representin~ said IR drop and providing a signal representing current I, and display means connected to said current determining mean~ ~or receiving said signal representing aurrent I and responsive thereto to display an indication of said current I, said di~play means . being mounted within said ho}low conductor adjacent said - openin~ wherebyisaid display is visible through said opening.
According to another form of the invention there is :;
.~ 20 provided apparatus for determining the IX drop in a hollowconductor ~or carrying a large current, where I is the : current in the hollow conduc~or and X is the reactance of the hollow conductox between a first and a second : point spaced longitudinally on said hollow conductor, the wall of said hollow conductor having loop conductor - ~ :
receiving openings at said first and second points, com_ ;
; prising a loop ~orming conductor extending within said hollow conductor between said first and second points, extending externally o~ said hollow conductor at said :~ 30 first and second points through said loop conductor receiving openings, and extending externally of said hollow conductor and adjacent the outer surface of the ~ .
CASE 2397 ~ ~
317~;
wall o~ said hollow conductor to form a loop, a voltage detector means connected to said loop forming conductor in said loop for detecting a voltage therein proportional to the IX drop between said ~ir~t andl second points, and to provide a voltage signal repre~entative o~ ~he IX
drop3 display means mounted to the wall o~ ~aid hollow conductor to provide a display visible remotely ~rom said hollow conductor, and means connecting said voltage de~
t~ctor means and said display means to apply said voltage signal to said display means and actuate said display responsive to said voltage signal to display an in.- :
dication o~ said IX drop.
The invention will be described with re~erence to ~:
the aacompanying drawings, in whic~
FIG~RE 1, lA and lB are simplified sectional dxawings of a portion of an unshielded bus indicating various measurement arrangements, a poxtion o~ a metal enclosed bus indicating various arrangements or determining ;~
parameters or the central con~uctor, and a portion of .: ~.
the metal enclosure of a metal enclosed bus indicating various arrangements for determîning paramekers ~or the metal enclosure, use~ul in describing the basic concept of the inventions . Figure 2 is a simpli~ied sectional drawing, partly in block form, showing a portion o~ a metal enclosed bus with a power supply and a display~
FIGURE 3 is a simplified sectional drawing, partly in block ~orm~ of a metal enclosed bus having apparatus `~
suitable for determining current in the central conductor; : ~-FIGURE 4 is a simpliied sectional drawings~ partly in block ~orm, o~ a metal enclosed buæ suitable or determining IX drop in a conductor, and - 12 _ :: ` . .' : ' . '. . . ! . ' ' . :
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~L~ ti3176 . .
Figure 5 is a schematic circuit diagram of a power ;~
supply suitable for use with the invention.
Referring to Figure 1 there is shown a small portion ~
of a bus lOa or hollow conductor lOa which carries a ~ -current. The bus lOa is supported by insulators (not shown). Assuming a current is flowing in conductor lOa, there will be a voltage drop which depends on the magnitude ~-. `
of the current and the resistance orimpedance involved as is well known in the art. It has been found that by ~`
using two terminal points 14 and 15 on the inside of conductor lOa and connecting a voltmeter 16 to these terminal points, using conductors 17 and 18 for the connection, that a voltage Vl is obtained where Vl= IR `
and where I is the current flowing in the conductor lOa and R is the resistance between points 14 and 15. It should be noted that voltmeter 16, conductors 17 and 18, ~
;. :
! and points 14 and 15 are all within the conductor lOa. ~ ;
Also, by using a loop formed with conductor 25 extending within conductor lOa and then extending ex~
ternally as shown, to connect to a voltmeter 26, a voltage V3 can be obtained. The voltage V3 is equal to IX where I is the current flowing in conductor lOa and X is the reactance in that portion enclosed by the loop.
The voltmeter 26 may be anywhere in the loop, that is it may be within conductor lOa or externally as shown.
In practice it is desirable to keep equipment or devices within the hollow conductor. This is particularly desirable when the voltage is high. If a piece of equipment, such as a voltmeter or display, is mounted externally it may be affected by the high voltage gra-dient and also, it may disrupt or interfere with the dielectric effect of the surrounding space.
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Also, as is knowm in the prior art, it is possible to determine IZ. The manner of doing so is included here for completeness. By u~ing two terminal points~
20 and 21 on the outer surace of conductor lOa, and ; connecting a voltmeter 22 to these terminal points using conductors 23 and 24, a voltage V2 is obtained w~ere V2 = IZ and where I is the current in the conductor lOa and Z is the impedancs between terminal points 20 and 21.
Referring now to Figure lA, there is shown a metal enclosed bus arrangement. A hollow central concluctor ~ ;
10 is surrounded by a metal enclosure 11. m e enclosure 11 is normally at ground potential and the ~entral con-ductor 10 is supported within enclosure 11 by insulators (not shown)~ Similar arrangements are shown for obtaining Vl,V2, and V3.
Referring to Figure lB, there is shown a metal enclosed bus with hollow central conductor 10 and metal enclosure 11. m e structure is the same as that for Figure lA. However in ~igure lB it is desired to know parameters relating to the metal enclosure. Voltmeter 16a is connected to terminal point~ 27 and 27a to give voltagq reading Vl representing the IR drop in the metal enclosure 11 between pointsl 27 and 27a. Voltmeter 26a is connected in the loop ~ormed by conductor 29 to give voltage V3 represent~ng the IX drop in the portion of metal enclosure 11 included in the loop.
Also~ to complete the description9 and volbmeter 22a is connected to terminal points 28 and 28a to give voltage reading V2 representing IZ drop in the metal enclosure 11 between points 28 and 28a.
It will be seen that it is possible to determine resistance, impedance and reactance~ I~ resis~tance is : , . .
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CASE 2397 ~
~ ;3i76 known, for example, it would be possible to obtain a d~termination of current from the IR drop. The re-sistance of conductor 10 changes with temperature.
I~ the temperature could be determined, the voltage V
ti~e. the IR drop) could be corrected to obtain current~
For this reason it is important to know temperatureO It is also important to Xnow temperature to ensure operating limits are not excseded~
As w~s previsouly mentio~e~, it is di~ficult to obtain temperature readings because the temperature sensor gives small output signals when comparecl to the voltages on the main conductor or bus. It i5 di~ficult to conduct the small voltage signals externally o~ the high voltage ~ystem It might be possible to use 3 battery powered amplifier within the central conductor to amplify signals be~ore conducting them to an outside point~ However this would involve problems with battery replacement and would not avoid the di~ficulties in having wires extending from a region of high potential to a region of low potential. To overcome these pro~lems and difficulties, the present invention provides a power supply which may be mounted within the main conductor, or ou~side the main conducto~ and closely adjacent, energized by the IR drop along the main conductor, and a display visible externally.
Referring to Figure 2, the central conductor 10 has an opening 30 covered by a metal screen 31. The screen 31 does not significantly impede vision but it prevents or inhibits abnormalities in voltage gradient that would otherwise be caused by opening 30. The metal screen is of a type referred to as a "Farraday screen'r~ In a preferr2d form the screen 31 is a double screenO ~pposite .. ~, . . `
-- CAS~ 2397 7~i the window or opening 30 and aligned therewith is an opening 32 in metal enclosure 11. The opening 32 is coverad with a tr~nspaxent material ~uch as a glass window 33. There i~ thus a path of vision fxom outside metal enclo~ure 11 through window 33 and screen 31 to the interior of central conductor 10, Mounted within central oonductor 10, ad~acent opening 30 is a display device 34. me display device 34 may provide a meter type display, but pre~erably it is a digital display using lighted segmental diqits or a binary light display. A binaxy light display may, for example~ have five separate lights whose on/of condition forms the binary number. m e visual display ~lay be picked up externally of the metal enclosure by an !' optical device and transmitted optically to a remote location or tran~Pormed again to an electrical signal and transmitted to a remote location as an electrical . .
signal for use as a record or transformed to a visual display or both.
A power supply 35 has input conductors 36 and 37 connected to terminal points 38 and 39~ The IR drop along conductor 10 provides a voltage to power the supply 35~ The input voltage provided by conductors 36 and 37 will vary with the current ~lowing in central conductor 10. One purpose of power supply 35 is to make use of a wide range of input voltages to provide a satisfactory supply voltage to display device 34 and to ~ -associated equipment as required. Ihe power supply 35 may~ for example, provide power for a sensor 40~ ~he sensor 40 may be a temperature sensitive element or it may have inputs for voltage.
Referring now to Figure 3, an arrangement i8 shown . ~ ~ . , , :
;3~7~
that is quite similar to that o~ Figure 2 but with a pick up for Vl~ Terminal points 41 and 42 are con-nected by conductors 43 and 44 to a ~oltage device 45 which determines Vl ~ IR. The sensor 40~ det~cts the ~-temperature of conductox 10. Knowing the temperature/
resistance relationship ~or conductor 10 and obtaining ;~:
temperature ~rom sensor 40' will enable a determination of re~istance to be made by device 45. With resistance .:~
known and voltage drop measured, the current can be determined and displayed by device 34. It will be seen that central conductor 10, between points 41 and : `~
42 may be said to act as its own ~hunt to give a voltage reading proportional to current Xt will be understood that display device 34 could display both the temperature detexmined by sen~or 40' and the voltage V1 determined by device 45. A aurrent determination could then be made externally if desired.
Referring briefly to Figure 4, there is shown a ~ -metal enclosed bus with central conductor 10 and metal enclosure 11. As in Figures 2 and 3 there is a trans_ parent window 33 in an opening 32 in metal enclosure 11.
A voltage sensing and display device 46 is positioned opposite the window openlng 32 and adjacent the outer surface oE central conduator 10~ The sizes in the drawings are~ of course, not to scala~ The sensing and display device 46 is in practice quite small and flat and would not extend away from the surface of conductor 10 by more than ona or two centimeters where tha spacing -between the central 7fonductor and the metal enclosure 11 A 30 might be 20 or more ~me as large.
Conductor 47 extends ~rom device 46 to opening 50, through opening 50, inside the hollow conductor to .~ . . . .
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1C~6317~6 :
~ :' opening 51, then back to device 46 to complete the loop.
Conductor 47 is kept as CloS3 as possible to the outer ` ~;
surface of conductor 10,. ~he voltage picked up by the loop fosmed by conductor 47 is voltage V3 = IX.
This may be displayed by device 46~ The ~implest form of device 46 is a voltmeter requirin,g no additional power supply. For more complex arrangements the device 46 may be powered by batteries or by a power supply similar to that descr~bed in connection with Figures 2 and 3. - .
While it is co~sidered that power supplies suitable ~ ~:
for use as the supply 35 described in connection with Figures 2 and 3 and mentioned in connection with Figure 4 could be designed by those skilled in the axt~ a brie~ description of a suitable supply will be given with reference to ~igure 5 to ensure the descxiption is complete Referring now to ~igure 5, a typical power supply 35 i5 shown, suitabl~ for use with the invention, The input conductor~ 36 and 37 from spaced points on the
This invention relates to the determination of electrical parameters and other parameters in an electrical bus.
For the purpose of this description, electrical bus may be considered to include a hollow conductor or bus which is not shielded along its length and a metal enclosed `; ?
bus having a hollow central conductor and a surrounding metal enclosure. The central conductor is supported within the metal enclosure by insulators. It is usual to operate the unshielded bus at lower potentials to carry currents of a large magnitude. For example, an unshielded bus might operate at a potential of perhaps 1000 to 5000 volts and `~
could carry currents of the order of a few thousand amperes.
It is usual to use metal enclosed bus at higher potentials where the metal enclosure is grounded and ofEers protection for the central conductor. For example, a metal enclosed bus might operate at a higher voltage, perhaps of the order of 20 kilovolts (kV) to 230 kV or higher and may carry currents of 5000 to 50 000 amperes or more. ~-In recent years with the trend to higher voltage, the ``
metal enclosed bus has seen considerable use for conducting -electric current for power transmission and distribution.
It is particularly useful at power generating stations where ;~
large amounts of power must be handled. It may contain an insulating gas, particularly at higher voltages. It may have means for circulating a gas within the metal enclosure ;~
for cooling purposes when large amounts of power are being handled. The present invention is suitable for determining parameters in such metal enclosed bus, although it may also be used to determine parameters in unshielded bus.
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~063~7~ CASE 2397 Paxameters which may be of interest in the operation or use of an electrical bus include: current I in the bus~
the temperature of the bus, the IR drop where R is t~e resistance of the bus between two longitudinally spaced points. IZ drop where Z is the impedance of the bus between two longitudinally spaced points, (IZ drop has been determined or bus in the prior art)~IX drop where X is the reactance of the bus between two longitudinally spaced ~;
points~ and the parameters R, X and Z themselves, No simple means has been devised in the past to determine some of these parameters with a desired accuracy. While values for IZ drop have been determined in the past, it has in itself not been of great practical value~ There have been a number of attempts made to determine aurrent and to determine temperature and perhaps ~ther parameters, It i8~ however~ quite dif~icult to determine parameters in a ragion of high voltage stxess and to conduct the signal representing the parameter Erom that region, ~ot only do the high voltages cause problems7 but the large currents cause heating and create magnetic fields which can in-terfere with a determination o~ various parameters, For example, it i5 ~uite common to obtain a temperature indicat~on on a metal enc~osed bus by affixing temperature `-sensitive patches to the outer surface of the centxa~
conductor where the patches are visible ~rom inspection windows. The patche~ change colour at specific temperatures~
This provides a very cheap way o~ determining if a specific temperature is exceeded~ }t is however unsatisfactory in that each patch provides an indication of ona temperature only For another example, it is known in an unshielded bus to have a current transformer surrounding the bus and ~;3i7~ ;
insulated therefrom to obtain an indication of current.
Such current trans~ormers are expen~ive and bulky and are inconvenient to use, particularly when high voltages are involved and the leads must be run from a high voltage region to a remote r~gion. m is type of arrangement has also been used with metal enclosed bus to obtain a current reading. The current transformar is in this arrangement mounted on an insulating bushing surrounding the central conductor and within the metal enclosura. The ~econdary -leads from the current transformer were usually passed to the outside of the metal enclo3ure throuyh a ring arrange-ment. Metal enclosed bus i5 usually designed ~or higher voltages and the voltage gradient between the central conductor and the me~al enclo~ure is usually large. A
current transformer is normally operated at ground potential ; and it is difficult to prevent flashovor and corona problems when a relatively bulky trans~ormer at ground potential is inserted into a bus where there is a large voltage gradient. --In addition, as the bus and enclosure are normally welded together w~en installed, it is difficult to inspect or repair such a current trans~ormer~
~nother prior ar~ arrangement avoids the pxoblem o~
having a current transformer within the metal enclosure of a metal enclosed bus. In this arrang~ment a gap is provided in the metal enclosure and the gap contains in~
v sulation. A conductor member capable of carrying large currents joins the adjacent ends of ~he metal enclosure extending externally over the insulation to ~orm a small loop. A current transformer is positioned over this loop which carries the current in the enclosure o~ a phase in the system. This current is substantially e~ual and opposite to the current in the central conductor and con-.~ .
_ 3 .'~ .
~6317~
sequently gives a xepresentation of the current in the ~entral conductor EIowever this arrangement requires a break or gap in the metal enclosure wherever a current reading is desired and this break must not only contain insulation but must be sealed in cases w~ere insulating B 9ga~ is contained within the metal enclosure. In addition, the metal enclosure may be subjected to ~luctuations of current from stxay fields originating externally where the central conductor would be shielded from such fluctuations.
Also, arrangements of this nature are relatively expensive.
It is, of course, desirable to obtain a reading of current in a bus as accurately and a~ economically as possible. Because o~ the large currents normally handled, small percentage errors can involve considerable amount~
of power. It is also desirable to measure or determine the IR drop in a bus during operation so that the re-sistive losses will be known. ~here have been a number o~ ways proposed to do this, but none appear to have had ;
the desired accuracy or simplicity~ Similarly, it is desirable to know the IX drop to have a complete under-standing o~ the system, and it appears there have been no prior art arrangements which give the desired accuracy and simplicity~
In addition it is desirable to know temperatures at i various places on a buso For example, in an unshielded bus it may be desirabla to know the temperature of the bus itself. In a metal enclosed bus it may be desirable to know the temperature not only of the bus or central conductor but perhaps within the central conductor or adjacent the central conductor. It is difficult to determine temperature because the temperature semsitive elements normally provide output voltages as signals _ 4 ~;3176 ;;
which represent temperature. These voltages are many orders smaller than the voltage gradient surrounding the central conductor. Small extraneous voltages might ;~-be picked up by the wires and affect the accuracy of the temperature indication. Also, the wires which carry the signals from the sensor would normally be at ground poten-tial. It is not desirable to have wires at ground potential extending through a large voltage gradient. Various ways have been proposed to overcome these problems,~for ;~
example by using a high frequency carrier signal to carry the temperature signal as a modulation of the carrier. ~, None of these have been completely satisfactory.
It has been discovered that an accurate determination can be made of various parameters of an operating bus by making these determinations in a specific manner and by making the determined values available externally without causing deterioration of the accuracy. ;
It has been found that by obtaining a voltage reading from longitudinally spaced points within an unshielded bus or within the central conductor of a metal enclosed bus, an accurate determination can be made of IR drop, `
where R is the resistance of the conductor between the points of measurement. It has been found that by obtain- ;
ing a voltage reading from a loop extending within the conductor of an unshielded bus or within the central conductor of a metal enclosed bus for a predetermined length, then brought outside the conductor and extended to form the loop, an accurate determination can be made at a ;
break in the loop for the IX drop where X is the reactance of the portion within the loop.
In an unshielded bus operating at lower voltages it may be feasible to bring the signals representing t:he ~' ', ' `"'.' ` ' ' ''': . ' '' , :
C~SE 2397 ~
~C~63176 paxameter externally on a twisted pair o~ wire~ without degrading the accuracy~ In a metal enclosad bu~ in accordance with the invention, values determined within the metal enclosure are made available externally by pro~iding a power supply and a visual display. ~or example, for values such as IR drop, t~mperature, or current det-ermined within tha central conductor, Zl display is positioned wnthin the central conductor to be visible through aligned openings in the central conductox and enclosure~ The opening in the central conductor is preferably covered with a Farraday screen and the opening in the metal enclosure is sealed with a transparent window. A power supply provides power to operate the display, and if required ma~ also provide power to the temperature sensor or other sensor~ In a preferred ~orm the power ~upply obtains its energizing voltage ~rom a voltage drop between longitud~nally spaced point~ on the inside of the centxal ;~
conductor using leads extending within the conductor to the lon~itudinally spaced points. A power supply could - 20 be energized by IX drop or IZ drop but, while the voltages `~
might be greater, thîs i8 not pre~erred. Transients are ;;
generally reactive in nature and related to frequency and would appear in a voltage for energiæing or powering a power supply ~rom IX or IZ drop~ It is thereore pre-ferred to powar the supply using IR drop which is sub-stantially ~ree o~ transients. It is also possible to have a supply using batteries~ In low voltage systems only, an external or remote power ~upply is ~easible.
Similarly9 for determining IX drop9 the voltage drop is normally determined adjacent the outer surface and the display w~uld also be adjacent the outer sur~ace It will be apparent that the loop could be broken wi1:hin : .
10~317~ C~SE 2397 the conductor and the di~play would then be within the conductor also Placing ~he di~play wi~hin the conductor would9 o~ course, avoid problem~ which might occur with a display in the high voltage gradient outside~ If a power supply i5 used to power the display9 ~t is desir-able to have the supply inside the hollow ~onductor whether the display is outside or inside The supply can thus be energized by IR drop~
m e temperature may be determined by usin~ a tem- -perature sensitive element or t~mpsrature sensor a~fixed .
to the main conductor or other place where a temperature determination is required. For example, the temperature `c: ;
~ensor could be ixed to thi~ inner surace o~ the hollow ~:
main bu~ ox conductor. A display means, and a power supply to provide power ~ox the display means, are within the conductor so that the display on the display means can be :
seen through a window or opening in the conductor. The power supply may be as previously mentioned~ energized by the IR drop between spaced points on the conductorO
The temperature sensor actuates the display to provide an indiaation of temperature~
m e invention al80 includes a determination of para-meters related to the metal enclosure of a metal enclosed bus. m e ~ame arrangement will provide a determination o~ IR drop, and IX drop and~knowing R or X9 the current may be determined~ The IR drop is determined using long-itudinally spaced points within the metal enclosure~ and ;~
the IX drop is determined using a loop extending in~
ternally and externally of a portion of the metal enclosure~ -If desired IZ dxop may also be determined as i~3 known in the prior art by u~ing longitudinally sp2lced points on the metal enclosure9 externally of the~ en~
closure.
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us, according ko one form of the invention there is providad a method for determining the IR drop in a .
hollow conductor for carrying a large current where I
is the current in the hollow conductor and R is the resistance in the hollow conductor between a irst and a seeond point spaced longitudinally on the conductor, compri~ing obtaining a voltage representation internally o said hollow conductor between irst and second ter-minal points within said eonductor on the inner sux~ace thereof correspo~ding to said ~irst and second pOilltS
r2spectively, displaying the voltage representation obtained on a display means within said conductor; said display being a determination o~ IR drop, and providing opening means to ma~e the displa~ vlsible externally~
According to another ~orm of the invention there is provided a method for determining the IX drop in a hollow conductor for carrying a large current where I is the ` .
current in the hollow conductor and X is the reactance o~ the hollow conductor between a ~irst and a ~econd point spaced longitudinally on the hollow conductor, com- .. .
prising providing a conductor in the orm of a loop ex-tending internally o said hollow conductor between said first and second points, extending through the w~lls of said hollow conductor at said first and second points . and extending externally to form the loop~ displaying the ; voltage representation obtained on a display means, said display being a determination o~ IX dropg and making : ~aid display visible at a region removed rom sai.d con_ ;:
du~tor :
According to another form of ~he invention there is provided a method for determining tempera$ure o~ a hollow aonductor or carrying a large current9 comprising plaeing . ~ .
_ 8 -~063176 CASE 23~7 a temperature sensor on the surface of said hollow conductor, connecting said temperature sensor with a ; .-: display means adjacent said hollow conductor to display a representation of temperature detexmined~ and making said display visible at a region removed from said hollow conductor~
According to another form of the invention there is provided a mekhod for determining current I in a hollow conductor for carrying a large current, comprising, ``
obtaining a voltage representation V internally o said :~
hollow conductor between a first ~nd a second terminal point on the inner surfaca of said hollow conductor, .:.
obtaining an indication of temperature ~rom a temperature sensor mounted on the inner surace o~ the wa.ll o~ said hollow conductor, determining the resistance R o~ said hollow conductor from the temperature resistance relation_ ship for said hollow conductor and the temperature from ~-:
the sensor, ~or that portion of the hollow conductor between said first and second terminal points~ determin_ ing the current I from the voltage representation V
where V ~ I R~ and displaying the determined value ~or ~.
the cuxrent I~ :;
According to another form of the invention there is provided apparatus for determining the IR drop in a hollow conductor for carrying a large current, where I is ~:
the current in the hollow conductor and R is the resis-tance of the hollow conductor betwe~n a first and a ~-second point spaced longitudinall on said hollow conductor;
comprising display means mounted within said hollow con~
ductor to the wall of said hollow conductor, said hollow conductor having an opening in said wall~ the edges of said opening defining a viewing opening for viewi~y the _ 9 _ : .
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10~3176 CASB 2397 display means externally of said hollow conductor, a voltage detector means mounted within said hollow con-ductox, first and second terminal points on the inner surface o~ said wall of said hollow conductor at said irst and second points respectively, input conductors extending within said hollow conductor and co~necting ~ ~:
each of said first and second terminal points to said voltage de~ector means to provide at said voltage det-e~*or means a voltage representative of IR drop between ~ ;:
said irst and second points, said voltage detector means providing a voltage signal representative of said :CR :
drop between said first and second points, and means ; connecting said voltage detector means and said display means to apply said voltage signal to said displa~ means and actuake said display means respon~ive thereto to display an indication o~ IR dxop According to another ~orm of the invention there is provided apparatus for determining the current } in a - :
hollow conductor having a wall for carrying a large :
current, said wall having a viewing opening therethrough, comprising a voltage detector means mounted within said ~`
hollow conductor, ~irst and se~ond terminal points on the inner sur~ace o~ sa~d wall ~orming said hollow conductor spaced longitudinally on said conductor, input :
conductors extending within said hollow conductor con~
necting said first and second terminal points to said voltage detector to provide a voltage at said voltage detector representing the IR drop between said first ~nd second terminal points~ where R is the resistance of said hollow conductor between said ~rst and second ~ :~
terminal points9 said voltage between means providing a ~ :
voltage signal representing said IR drop9 a temperature sensor mountsd within said hollow conduc~or to the wall _ 10 -, -~'~ . : . . . ' .
~ 1063176 CASE 2397 : ofsaid h~llow conductor to obtaln a signal representing the temperature o~ said hollow conductor, means connecting said voltage sensor to said voltage detector to apply .~ thereto said signal repre~enting the t~mperatur~ o~ said conductor, means in said voltage detector means responsive to said temperature signal to provide a signal represent_ . ing resistance R based on the tempexature/resistance -~
: relationship of said hollow conductor current determining means connected to said voltage detector means to receive ~ :
said signal representing resi~tance R and said voltage -signal representin~ said IR drop and providing a signal representing current I, and display means connected to said current determining mean~ ~or receiving said signal representing aurrent I and responsive thereto to display an indication of said current I, said di~play means . being mounted within said ho}low conductor adjacent said - openin~ wherebyisaid display is visible through said opening.
According to another form of the invention there is :;
.~ 20 provided apparatus for determining the IX drop in a hollowconductor ~or carrying a large current, where I is the : current in the hollow conduc~or and X is the reactance of the hollow conductox between a first and a second : point spaced longitudinally on said hollow conductor, the wall of said hollow conductor having loop conductor - ~ :
receiving openings at said first and second points, com_ ;
; prising a loop ~orming conductor extending within said hollow conductor between said first and second points, extending externally o~ said hollow conductor at said :~ 30 first and second points through said loop conductor receiving openings, and extending externally of said hollow conductor and adjacent the outer surface of the ~ .
CASE 2397 ~ ~
317~;
wall o~ said hollow conductor to form a loop, a voltage detector means connected to said loop forming conductor in said loop for detecting a voltage therein proportional to the IX drop between said ~ir~t andl second points, and to provide a voltage signal repre~entative o~ ~he IX
drop3 display means mounted to the wall o~ ~aid hollow conductor to provide a display visible remotely ~rom said hollow conductor, and means connecting said voltage de~
t~ctor means and said display means to apply said voltage signal to said display means and actuate said display responsive to said voltage signal to display an in.- :
dication o~ said IX drop.
The invention will be described with re~erence to ~:
the aacompanying drawings, in whic~
FIG~RE 1, lA and lB are simplified sectional dxawings of a portion of an unshielded bus indicating various measurement arrangements, a poxtion o~ a metal enclosed bus indicating various arrangements or determining ;~
parameters or the central con~uctor, and a portion of .: ~.
the metal enclosure of a metal enclosed bus indicating various arrangements for determîning paramekers ~or the metal enclosure, use~ul in describing the basic concept of the inventions . Figure 2 is a simpli~ied sectional drawing, partly in block form, showing a portion o~ a metal enclosed bus with a power supply and a display~
FIGURE 3 is a simplified sectional drawing, partly in block ~orm~ of a metal enclosed bus having apparatus `~
suitable for determining current in the central conductor; : ~-FIGURE 4 is a simpliied sectional drawings~ partly in block ~orm, o~ a metal enclosed buæ suitable or determining IX drop in a conductor, and - 12 _ :: ` . .' : ' . '. . . ! . ' ' . :
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~L~ ti3176 . .
Figure 5 is a schematic circuit diagram of a power ;~
supply suitable for use with the invention.
Referring to Figure 1 there is shown a small portion ~
of a bus lOa or hollow conductor lOa which carries a ~ -current. The bus lOa is supported by insulators (not shown). Assuming a current is flowing in conductor lOa, there will be a voltage drop which depends on the magnitude ~-. `
of the current and the resistance orimpedance involved as is well known in the art. It has been found that by ~`
using two terminal points 14 and 15 on the inside of conductor lOa and connecting a voltmeter 16 to these terminal points, using conductors 17 and 18 for the connection, that a voltage Vl is obtained where Vl= IR `
and where I is the current flowing in the conductor lOa and R is the resistance between points 14 and 15. It should be noted that voltmeter 16, conductors 17 and 18, ~
;. :
! and points 14 and 15 are all within the conductor lOa. ~ ;
Also, by using a loop formed with conductor 25 extending within conductor lOa and then extending ex~
ternally as shown, to connect to a voltmeter 26, a voltage V3 can be obtained. The voltage V3 is equal to IX where I is the current flowing in conductor lOa and X is the reactance in that portion enclosed by the loop.
The voltmeter 26 may be anywhere in the loop, that is it may be within conductor lOa or externally as shown.
In practice it is desirable to keep equipment or devices within the hollow conductor. This is particularly desirable when the voltage is high. If a piece of equipment, such as a voltmeter or display, is mounted externally it may be affected by the high voltage gra-dient and also, it may disrupt or interfere with the dielectric effect of the surrounding space.
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Also, as is knowm in the prior art, it is possible to determine IZ. The manner of doing so is included here for completeness. By u~ing two terminal points~
20 and 21 on the outer surace of conductor lOa, and ; connecting a voltmeter 22 to these terminal points using conductors 23 and 24, a voltage V2 is obtained w~ere V2 = IZ and where I is the current in the conductor lOa and Z is the impedancs between terminal points 20 and 21.
Referring now to Figure lA, there is shown a metal enclosed bus arrangement. A hollow central concluctor ~ ;
10 is surrounded by a metal enclosure 11. m e enclosure 11 is normally at ground potential and the ~entral con-ductor 10 is supported within enclosure 11 by insulators (not shown)~ Similar arrangements are shown for obtaining Vl,V2, and V3.
Referring to Figure lB, there is shown a metal enclosed bus with hollow central conductor 10 and metal enclosure 11. m e structure is the same as that for Figure lA. However in ~igure lB it is desired to know parameters relating to the metal enclosure. Voltmeter 16a is connected to terminal point~ 27 and 27a to give voltagq reading Vl representing the IR drop in the metal enclosure 11 between pointsl 27 and 27a. Voltmeter 26a is connected in the loop ~ormed by conductor 29 to give voltage V3 represent~ng the IX drop in the portion of metal enclosure 11 included in the loop.
Also~ to complete the description9 and volbmeter 22a is connected to terminal points 28 and 28a to give voltage reading V2 representing IZ drop in the metal enclosure 11 between points 28 and 28a.
It will be seen that it is possible to determine resistance, impedance and reactance~ I~ resis~tance is : , . .
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CASE 2397 ~
~ ;3i76 known, for example, it would be possible to obtain a d~termination of current from the IR drop. The re-sistance of conductor 10 changes with temperature.
I~ the temperature could be determined, the voltage V
ti~e. the IR drop) could be corrected to obtain current~
For this reason it is important to know temperatureO It is also important to Xnow temperature to ensure operating limits are not excseded~
As w~s previsouly mentio~e~, it is di~ficult to obtain temperature readings because the temperature sensor gives small output signals when comparecl to the voltages on the main conductor or bus. It i5 di~ficult to conduct the small voltage signals externally o~ the high voltage ~ystem It might be possible to use 3 battery powered amplifier within the central conductor to amplify signals be~ore conducting them to an outside point~ However this would involve problems with battery replacement and would not avoid the di~ficulties in having wires extending from a region of high potential to a region of low potential. To overcome these pro~lems and difficulties, the present invention provides a power supply which may be mounted within the main conductor, or ou~side the main conducto~ and closely adjacent, energized by the IR drop along the main conductor, and a display visible externally.
Referring to Figure 2, the central conductor 10 has an opening 30 covered by a metal screen 31. The screen 31 does not significantly impede vision but it prevents or inhibits abnormalities in voltage gradient that would otherwise be caused by opening 30. The metal screen is of a type referred to as a "Farraday screen'r~ In a preferr2d form the screen 31 is a double screenO ~pposite .. ~, . . `
-- CAS~ 2397 7~i the window or opening 30 and aligned therewith is an opening 32 in metal enclosure 11. The opening 32 is coverad with a tr~nspaxent material ~uch as a glass window 33. There i~ thus a path of vision fxom outside metal enclo~ure 11 through window 33 and screen 31 to the interior of central conductor 10, Mounted within central oonductor 10, ad~acent opening 30 is a display device 34. me display device 34 may provide a meter type display, but pre~erably it is a digital display using lighted segmental diqits or a binary light display. A binaxy light display may, for example~ have five separate lights whose on/of condition forms the binary number. m e visual display ~lay be picked up externally of the metal enclosure by an !' optical device and transmitted optically to a remote location or tran~Pormed again to an electrical signal and transmitted to a remote location as an electrical . .
signal for use as a record or transformed to a visual display or both.
A power supply 35 has input conductors 36 and 37 connected to terminal points 38 and 39~ The IR drop along conductor 10 provides a voltage to power the supply 35~ The input voltage provided by conductors 36 and 37 will vary with the current ~lowing in central conductor 10. One purpose of power supply 35 is to make use of a wide range of input voltages to provide a satisfactory supply voltage to display device 34 and to ~ -associated equipment as required. Ihe power supply 35 may~ for example, provide power for a sensor 40~ ~he sensor 40 may be a temperature sensitive element or it may have inputs for voltage.
Referring now to Figure 3, an arrangement i8 shown . ~ ~ . , , :
;3~7~
that is quite similar to that o~ Figure 2 but with a pick up for Vl~ Terminal points 41 and 42 are con-nected by conductors 43 and 44 to a ~oltage device 45 which determines Vl ~ IR. The sensor 40~ det~cts the ~-temperature of conductox 10. Knowing the temperature/
resistance relationship ~or conductor 10 and obtaining ;~:
temperature ~rom sensor 40' will enable a determination of re~istance to be made by device 45. With resistance .:~
known and voltage drop measured, the current can be determined and displayed by device 34. It will be seen that central conductor 10, between points 41 and : `~
42 may be said to act as its own ~hunt to give a voltage reading proportional to current Xt will be understood that display device 34 could display both the temperature detexmined by sen~or 40' and the voltage V1 determined by device 45. A aurrent determination could then be made externally if desired.
Referring briefly to Figure 4, there is shown a ~ -metal enclosed bus with central conductor 10 and metal enclosure 11. As in Figures 2 and 3 there is a trans_ parent window 33 in an opening 32 in metal enclosure 11.
A voltage sensing and display device 46 is positioned opposite the window openlng 32 and adjacent the outer surface oE central conduator 10~ The sizes in the drawings are~ of course, not to scala~ The sensing and display device 46 is in practice quite small and flat and would not extend away from the surface of conductor 10 by more than ona or two centimeters where tha spacing -between the central 7fonductor and the metal enclosure 11 A 30 might be 20 or more ~me as large.
Conductor 47 extends ~rom device 46 to opening 50, through opening 50, inside the hollow conductor to .~ . . . .
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1C~6317~6 :
~ :' opening 51, then back to device 46 to complete the loop.
Conductor 47 is kept as CloS3 as possible to the outer ` ~;
surface of conductor 10,. ~he voltage picked up by the loop fosmed by conductor 47 is voltage V3 = IX.
This may be displayed by device 46~ The ~implest form of device 46 is a voltmeter requirin,g no additional power supply. For more complex arrangements the device 46 may be powered by batteries or by a power supply similar to that descr~bed in connection with Figures 2 and 3. - .
While it is co~sidered that power supplies suitable ~ ~:
for use as the supply 35 described in connection with Figures 2 and 3 and mentioned in connection with Figure 4 could be designed by those skilled in the axt~ a brie~ description of a suitable supply will be given with reference to ~igure 5 to ensure the descxiption is complete Referring now to ~igure 5, a typical power supply 35 i5 shown, suitabl~ for use with the invention, The input conductor~ 36 and 37 from spaced points on the
2~ conductor are shown where they ars connected to the supply. A transformer 53 has its primary winding con~
nected to conductors 36 and 37. The transformer 53 has a center_tapped secondary winding~ The center tap is connected to the common conductor 54. The ends o~ the :-secondary windin~ are connected each to a diode 55 and 56. The output of the diodes 55 and 56 is connected to a choke 57, The output rom choke 57 has a cap_ :
acitor 58 connected to a common connection 54~ The output of cho~e 57 is connected to a volta~e re-gulator 59, w~ich may conveniently be a zener diode.
The output of the regulator 59 p~sses through a diode 60, to pr~vent reverse flow~ and a resistor 61 to the :-- 18 _ - ~ ~ . . ... .
;, : . . ,
nected to conductors 36 and 37. The transformer 53 has a center_tapped secondary winding~ The center tap is connected to the common conductor 54. The ends o~ the :-secondary windin~ are connected each to a diode 55 and 56. The output of the diodes 55 and 56 is connected to a choke 57, The output rom choke 57 has a cap_ :
acitor 58 connected to a common connection 54~ The output of cho~e 57 is connected to a volta~e re-gulator 59, w~ich may conveniently be a zener diode.
The output of the regulator 59 p~sses through a diode 60, to pr~vent reverse flow~ and a resistor 61 to the :-- 18 _ - ~ ~ . . ... .
;, : . . ,
3~76 output indicated with a plus sign. A rechargeable battery 62 is floated across the output. The power supply 35 is quite conventional and it is believed no further explanation is required.
In practice, the input conductors 36 and 37 might total 150 ft. in length. When the conductor 10 is carrying 15 000 to 30 000 amperes the input voltage thus obtained might then be of the order of 1.35 to 2.7 volts across the primary of transformer 53. The secondary of transformer 53 has a voltage on either side of the center tap between 15 and 30 volts to give a voltage across capacitor 58 of perhaps 20 to 40 volts. This is sufficient for the voltage regulator to provide an output of the order of 12 volts. It will be seen that the power supply will operate down to about half rated current in the central ~, conductor and below that the ba'ctery 62 must provide power.
The figures given in this paragraph are given only as examples and to provide a better understanding of the power supply. A similar supply could be readily designed for other voltage and currents.
It is believed that the invention in all its forms and variations will be clesr from l:he preceding description.
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In practice, the input conductors 36 and 37 might total 150 ft. in length. When the conductor 10 is carrying 15 000 to 30 000 amperes the input voltage thus obtained might then be of the order of 1.35 to 2.7 volts across the primary of transformer 53. The secondary of transformer 53 has a voltage on either side of the center tap between 15 and 30 volts to give a voltage across capacitor 58 of perhaps 20 to 40 volts. This is sufficient for the voltage regulator to provide an output of the order of 12 volts. It will be seen that the power supply will operate down to about half rated current in the central ~, conductor and below that the ba'ctery 62 must provide power.
The figures given in this paragraph are given only as examples and to provide a better understanding of the power supply. A similar supply could be readily designed for other voltage and currents.
It is believed that the invention in all its forms and variations will be clesr from l:he preceding description.
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Claims (16)
1. A method for determining parameters in a hollow con-ductor between first and second points spaced longitudinally on said conductor, said parameters being related to a large current I carried by said conductor, comprising:
obtaining a voltage representation with respect to said first and second points, said voltage representation being related to said current I and said parameters, displaying said voltage representation from the immediate vicinity of said hollow conductor, and providing means to make the display visible at a region removed from said conductor.
obtaining a voltage representation with respect to said first and second points, said voltage representation being related to said current I and said parameters, displaying said voltage representation from the immediate vicinity of said hollow conductor, and providing means to make the display visible at a region removed from said conductor.
2. A method for determining the IR drop in a hollow conductor for carrying a large current where I is the current in the hollow conductor and R is the resistance in the hollow conductor between a first and a second point spaced longitudinally on the conductor, comprising:
obtaining a voltage representation internally of said hollow conductor between first and second terminal points within said conductor on the inner surface thereof, corresponding to said first and second points respectively, displaying the voltage representation obtained on a display means within said conductor, said display being a determination of RI drop, and providing opening means to make the display visible externally.
obtaining a voltage representation internally of said hollow conductor between first and second terminal points within said conductor on the inner surface thereof, corresponding to said first and second points respectively, displaying the voltage representation obtained on a display means within said conductor, said display being a determination of RI drop, and providing opening means to make the display visible externally.
3. A method for determining the IX drop in a hollow conductor for carrying a large current where I is the current in the hollow conductor and X is the reactance of the hollow conductor between a first and a second point spaced longitudinally on the hollow conductor, comprising:
providing a conductor in the form of a loop extending internally of said hollow conductor between said first and second points, extending through the walls of said hollow conductor at said first and second points and extending externally to form the loop, obtaining a voltage representation at an open place in said loop, displaying the voltage representation obtained on a display means, said display being a determination of IX drop, and making said display visible at a region removed from said conductor.
providing a conductor in the form of a loop extending internally of said hollow conductor between said first and second points, extending through the walls of said hollow conductor at said first and second points and extending externally to form the loop, obtaining a voltage representation at an open place in said loop, displaying the voltage representation obtained on a display means, said display being a determination of IX drop, and making said display visible at a region removed from said conductor.
4. A method as defined in any one of claim 2 or 3 and further comprising:
obtaining a voltage from points spaced longitudinally of said hollow conductor on the inner surface thereof, said voltage being caused by the IR drop along said conductor, regulating said voltage to provide a power supply for said display means.
obtaining a voltage from points spaced longitudinally of said hollow conductor on the inner surface thereof, said voltage being caused by the IR drop along said conductor, regulating said voltage to provide a power supply for said display means.
5. Apparatus for determining parameters in a hollow conductor for carrying a large current, where I is the current in the hollow conductor, R is the resistance parameter of the hollow conductor between first and second points spaced longitudinally on said conductor and X is the reactance parameter of the hollow conductor between said first and second points, comprising:
voltage detector means mounted adjacent the wall of said hollow conductor for obtaining a representation of voltage between said first and second points, said representation of voltage being related to current and to one of the parameters R and X, display means mounted adjacent said hollow conductor and responsive to said voltage representation to actuate said display means to display the value of said representation of voltage.
voltage detector means mounted adjacent the wall of said hollow conductor for obtaining a representation of voltage between said first and second points, said representation of voltage being related to current and to one of the parameters R and X, display means mounted adjacent said hollow conductor and responsive to said voltage representation to actuate said display means to display the value of said representation of voltage.
6. Apparatus for determining the IR drop in a hollow conductor for carrying a large current, where I is the current in the hollow conductor and R is the resistance of the hollow conductor between a first and a second point spaced longitudinally on said hollow conductor, comprising display means mounted within said hollow conductor to the wall of said hollow conductor, said hollow conductor having an opening in said wall, the edges of said opening defining a viewing opening for viewing the display means externally of said hollow conductor, a voltage detector means mounted within said hollow conductor, first and second terminal points on the inner surface of said wall of said hollow conductor at said first and second points respectively, input conductors, extending within said hollow conductor and connecting each of said first and second terminal points to said voltage detector means to provide to said voltage detector means a voltage representative of the IR drop between said first and second points, said voltage detector means providing a voltage signal representative of said IR drop between said first and second points, and means connecting said voltage detector means and said display means to apply said voltage signal to said display means and actuate said display means responsive thereto to display an indication of IR drop.
7. Apparatus as defined in claim 6 and further including a power supply means mounted within said conductor to provide power to said display means.
8. Apparatus as defined in claim 7 in which said power supply means comprises:
terminal places on the inner surface of said wall of said conductor spaced longitudinally on said conductor, voltage supply conductors each connecting a respective terminal place to said power supply means to provide thereto a voltage according to the voltage drop between said terminal places, and regulating means to provide a controlled power for said diplay means.
terminal places on the inner surface of said wall of said conductor spaced longitudinally on said conductor, voltage supply conductors each connecting a respective terminal place to said power supply means to provide thereto a voltage according to the voltage drop between said terminal places, and regulating means to provide a controlled power for said diplay means.
9. Apparatus as defined in claim 6, 7 or 8 and further comprising:
a temperature sensitive sensor mounted to said conductor within conductor to give a signal representing a determination of the temperature of said conductor, and means to apply said signal representing a determination of temperature to said display means for display thereon.
a temperature sensitive sensor mounted to said conductor within conductor to give a signal representing a determination of the temperature of said conductor, and means to apply said signal representing a determination of temperature to said display means for display thereon.
10. Apparatus as defined in claim 6, 7 or 8 in which said hollow conductor is the central conductor of a metal enclosed bus and is surrounded by a metal enclosure concentric with said central conductor, said metal enclosure having an opening therein aligned with the opening in the central conductor for viewing the display.
11. Apparatus as defined in claim 6, 7 or 8 and further including a metal screen over the opening in said hollow conductor to inhibit distortion of the voltage gradient at said opening in said hollow conductor.
12. Apparatus for determining the IX drop in a hollow conductor for carrying a large current, where I is the current in the hollow conductor and X is the reactance of the hollow conductor between a first and a second point spaced longitudinally on said conductor, the wall of said hollow conductor having loop conductor receiving openings at said first and second points, comprising:
a loop forming conductor extending within said hollow conductor between said first and second points, extending externally of said hollow conductor at said first and second points through said loop conductor receiving openings, and extending externally of said hollow conductor and adjacent the outer surface of the wall of said hollow conductor to form a loop, a voltage detector means connected to said loop forming conductor in said loop for detecting a voltage therein proportional to the IX drop between said first and second points, and to provide a voltage signal representative of the IX
drop, display means mounted to the wall of said hollow conductor to provide a display visible remotely from said hollow conductor, and means connecting said voltage detector means and said display means to apply said voltage signal to said display means and actuate said display responsive to said voltage signal to display an indication of said IX drop.
a loop forming conductor extending within said hollow conductor between said first and second points, extending externally of said hollow conductor at said first and second points through said loop conductor receiving openings, and extending externally of said hollow conductor and adjacent the outer surface of the wall of said hollow conductor to form a loop, a voltage detector means connected to said loop forming conductor in said loop for detecting a voltage therein proportional to the IX drop between said first and second points, and to provide a voltage signal representative of the IX
drop, display means mounted to the wall of said hollow conductor to provide a display visible remotely from said hollow conductor, and means connecting said voltage detector means and said display means to apply said voltage signal to said display means and actuate said display responsive to said voltage signal to display an indication of said IX drop.
13. Apparatus as defined in claim 12 in which said hollow conductor is the central conductor of a metal enclosed bus and is surrounded by a metal enclosure concentric with said central conductor, said metal enclosure having an opening therein for viewing said display means externally of said metal enclosure.
14. Apparatus as defined in claim 12 and further including power supply means to provide power for said display means, comprising:
a pair of terminal places on the wall of said hollow conductor spaced longitudinally along said conductor, voltage supply conductors each connecting a respective one of said terminal places to said power supply means to provide a voltage according to the voltage drop between said terminal places, and regulating means to provide a controlled power for said display means.
a pair of terminal places on the wall of said hollow conductor spaced longitudinally along said conductor, voltage supply conductors each connecting a respective one of said terminal places to said power supply means to provide a voltage according to the voltage drop between said terminal places, and regulating means to provide a controlled power for said display means.
15. Apparatus as defined in claim 6 or 12 in which said display means has a plurality of lights each of which has an on and off condition, the actuation of selected lights giving a binary visible display.
16. Apparatus as defined in claim 6 or 12 in which said display means has a plurality of lights each of which has an on and off condition, the actuation of selected lights giving a visible binary display, and fibre optic light guides having first terminal ends adjacent said display and extending to second terminal ends positioned remotely from said display to provide information from said display at said second terminal ends.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA247,145A CA1063176A (en) | 1976-03-04 | 1976-03-04 | Sensing electrical parameters inside conductors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA247,145A CA1063176A (en) | 1976-03-04 | 1976-03-04 | Sensing electrical parameters inside conductors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1063176A true CA1063176A (en) | 1979-09-25 |
Family
ID=4105385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA247,145A Expired CA1063176A (en) | 1976-03-04 | 1976-03-04 | Sensing electrical parameters inside conductors |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1063176A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0139068A1 (en) * | 1983-08-31 | 1985-05-02 | Hydro-Quebec | An apparatus for sensing and measuring a current on a power transmission line |
| FR2673762A1 (en) * | 1991-03-05 | 1992-09-11 | Merlin Gerin | Device for measuring the post-arc current of an electrical power switch |
| WO1994019700A1 (en) * | 1993-02-24 | 1994-09-01 | Siemens Aktiengesellschaft | Arrangement for detecting the actual value of a measurement at high potential |
| WO2009109507A2 (en) * | 2008-03-06 | 2009-09-11 | Siemens Aktiengesellschaft | Device for capturing measurement variables and high-voltage system |
-
1976
- 1976-03-04 CA CA247,145A patent/CA1063176A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0139068A1 (en) * | 1983-08-31 | 1985-05-02 | Hydro-Quebec | An apparatus for sensing and measuring a current on a power transmission line |
| FR2673762A1 (en) * | 1991-03-05 | 1992-09-11 | Merlin Gerin | Device for measuring the post-arc current of an electrical power switch |
| WO1994019700A1 (en) * | 1993-02-24 | 1994-09-01 | Siemens Aktiengesellschaft | Arrangement for detecting the actual value of a measurement at high potential |
| WO2009109507A2 (en) * | 2008-03-06 | 2009-09-11 | Siemens Aktiengesellschaft | Device for capturing measurement variables and high-voltage system |
| WO2009109507A3 (en) * | 2008-03-06 | 2009-11-12 | Siemens Aktiengesellschaft | Device for capturing measurement variables and high-voltage system |
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