DE2031596C3 - Device for temperature monitoring of a cable - Google Patents

Description

3. Device according to claims 1 and 2, 30-fold means determined and without interference characterized in that the transmitter (28) as surrounding fields to a monitoring point via radio transmitter trained and with one who can be carried.

housing outer wall of a cable end closure bün- This object is achieved in that according to

dig recessed antenna (32, 50) is connected. of the invention in a device of the yorgenann-

4. Device according to claims 1 to 3, 35 th type one over the length of the measurement characterized in that the housing (47) to be detected cable section with the current conductor is arranged on a corona ring. of the cable in thermal and only at the end of the

5. Device according to claims 1 to 4, 'section standing in electrical contact characterized in that the radio transmitter control line with temperature-dependent conductivity (28) contains a two-phase modulator (30). 40 is provided and together with the conductor

6. The device according to claim 1, gekennzeich- a branch of the Wheatstone bridge forms, which net by a plurality of unequally long control values together with one of the measured values (output voltage lines, the openings of the Wheatstone Bridge radiating at intervals from one another at one end with the current conductor (H ') transmitter in an electric and magnetic field are connected and is arranged to measure their conductive 45 shielding housing.

together with the corresponding section In a branch of a bridge circuit temperature

of the conductor (H ') to arrange a branch of a heat-sensitive display element and

Form stone bridge (64, 65, 66). when the bridge equilibrium is disturbed in the

7. Apparatus according to claim 6, marked bridge diagonal flowing current for triggering net by switching devices, by means of which the 50 alarm devices can be used, is already Wheatstone bridges (64, 65, 66) known (German Patent 969 456). Such send measuring devices optionally with a type of temperature monitoring is however with the Radio transmitter (28) can be connected. Monitoring a long stretch of high voltage cable because of the high voltage

55 kabeis occurring alternating, in the resistance wire Magnetic fields that induce interference voltages are unusable because these interference voltages cause the

The invention relates to a device for over-measuring effect would by far predominate. Besides that guarding the middle, along a cable section, there would be the danger that it would be between the rulers Temperature by means of one of a 60 voltage cables and the essentially ground direct current source fed, a Wheatstone potential measuring line to voltage through-bridge having measuring device. breaks would also result in sensitive disturbances Operation of electrical supply networks results in measurement, if not in destruction makes it necessary to carry the temperature of longer cables - the measuring apparatus, Sections, in particular the temperature of the jacket- 65 The supplying power to the Wheatstone Bridge ter high voltage cables, to be monitored continuously. With measuring device serving direct current im Cables laid in the ground can, particularly in source, advantageously have a transformer In dry areas, there is a large thermal load, the primary winding of which is the conductor itself

and its secondary winding with a circuit. In Fig. 2, an embodiment of the invention is

for rectifying the branched off alternating current, in which the degree of detuning

and generating the desired direct current using a Wheatstone bridge as a measure of the

is bound. To avoid any direct electrical change in the electrical conductivity of the control

trical connections between the one used on the power line. The control line 10 is at

tial of the conductor located measuring device of the production of the conductor 11 in this one-

and the surveillance bed on the ground.

tion, the transmitter is designed as a radio transmitter and nickel can be used as a satisfactory material for the control glue with a cable end in the outer wall of the housing. Since, according to a closure, the flush-mounted antenna is connected to the control line 10 as a prerequisite of the invention. Because both the measuring device used to determine the conductor 11 and the conductor to be monitored should be at the same temperature, the transmitter must also be connected to a cable end connection between the control line 10 and the monitoring station to transmit the measurement data to fresh insulators. the current conductor 11 a thermal connection is arranged, measurement errors are caused by interference 15. Since the cable insulation is impregnated with oil, the insulator of the control line 10 should be able to originate from this oil system, avoid swelling between the control line and the transmission line, so that the di- insoluble. Possible materials for this are nylon and cotton, which are currently made on the spot. The Steuerlei measurements a high degree of accuracy up averaging 10 is generally along the axis of ways. The housing of the current conductor 11 is arranged on the cable termination. At one end of the measuring device to be arranged there is preferably an electrical-monitoring cable section, the control line 10 is trically and magnetically shielded in order to also be short-circuited externally with the current conductor 11; avoid these disturbances ZM. connection point is at the measuring device

Devices for the wireless transmission of opposite ends of said conductor measured values a line route, for example the 25 route. In the area of the measuring device is the Attenuation values of a line section in the dependent control line 10 by one in the drawing not speed of the frequency are, for example, from the dm provided press fit from the cable termination German Auslegeschrift 1218 909 known. Such brought out. The control line 10 and the return devices However, they are only used for bridging conductors 11 (in this embodiment one of the conductors Rung larger distances between two measuring 30 of the cable) are connected in series and form one put. The special requirements for the Er branch of Wheatstone Bridge 12. The others subject of the invention is sufficient such a device three branches contain fixed resistors 13, 14 and However not. 15 and a resistor 16 with a variable

To the average temperatures of individual partial center tap, with which the bridge 12 werstrecken matched of a conductor can be displayed separately. Over one diagonal, between the According to a further development of the invention, connections 19 and 20 are a direct voltage application Several control lines of unequal length are placed in the file, while the remaining diagonals are placed over the other diagonal is tapped from each other at one end of the output voltage. The schematic connected to the current conductor and thus form the equal measurement shown by the dashed line 21 their conductivity together with the electricity source 40 includes an alternating current source 22 and speaking section of the conductor a branch a rectifier 23. The alternating current source in the Whe ^ tstone Bridge. Fig. 2 is a transformer whose primary winding

In the 'drawing are the current conductor 11 of the transmission cable in a schematic manner. the

some embodiments of the invention shown secondary winding 24 of the transformer is with the

which are described in more detail below. 45 AC power source 22 output connections

It shows bound, which in turn are connected to the rectifier 23

Fig. 1 is a side view of a cable connected. The rectifier 23 in FIG. 2

end closure arranged temperature measuring device can z. B. a well-known full-wave diode rectifier

tion and transmission system, be a judge. The output of the rectifier 23 is

F i g. 2 a schematic circuit diagram of the temperature 50 connected to a voltage regulator 27, the one

Temperature measuring device and the transmitter according to FIG. 1, constant voltage at the connections 19 and 20

3 provides a schematic circuit diagram of the two-phase Wheatstone bridge 12,

gen modulator according to FIG. 2, Such voltage regulators are known.

F i g. 4 is a side view of the corona for smoothing the output signal is at the output

ring of an isolator arranged measuring and transmitting 55 of the rectifier 23 a corresponding filter before-

device as a further exemplary embodiment of the He- seen. The in Fig. The filter shown in FIG. 2 includes a

finding, inductance 25 and a capacitance 26. An additional

. F i g. 5 is a plan view of the housing of the filtering device, due to a large capacity 17

Fig. 1, achieved that the control line 10 with the return line

6 shows a detailed view of the transmitting antenna connected 60 11 in order to avoid possibly inductively generated alternations.

according to Fig. 1 to reduce self-voltages in these conductors.

7 shows a section through a high voltage. The direct current source 21 can also be a battery

cable with a multicore embedded in the center with constant tension, which is fed by a

gen control line, derived from the alternating current of this conductor 11

F i g. 8 a schematic !; Circuit diagram of an execution 65 current is charged.

Form of the invention for determining the average output voltage of the Wheatstone

Ren temperatures of several sections of a bridge 12 is based on the input of a radio transmitter

Power cord. 28 eeeeben. the version shown in the

2-031 598

form contains a two-phase modulator 30, so that, as shown in Fig. 1, d \ _P in F; ->

Radio interference from electrical discharges or Vorcht'uS 1 dl r J üsch shown

Transits in the power cable 11 kept small, built in we ches al "vS ^ n.Ja« ^Gch ^ ^se

can be. The transmitter 28 comprises a span conductor 11 vweesehenen KhS ⁸ μ '

voltage-controlled oscillator 29, forming a two-phase 5 is Da f housing Un Γ Ψ ϊ ™ 1 ^a "

Modulator 30 and a power amplifier ^! and triscl en shielding from AllfnZ * F ^d

at its output a modulation signal, the wall of which is embedded KAI ί ^ Frequency as a function of the applied input output frequency ΐ d "^^ order of magnitude of

SSS ¹ S ⁸ I Γ "'' ¹ " ¹ · ^De - ^s P ^annun B ^{SgeSteUCrte 15 100MHz} a diameter JSÄJätT

Oscillator 29 preferably has an output frequency of about 20 cm. It is zero-beam ϊ

quenz m of the order of 500 Hz. It can kai polarized. As in Fig 6 JS contains * A ^

this any known embodiment of a Oscil- 32 a flat electrically conductive Metarfitt ^ "T

lator or a voltage-frequency converter of a cylindrical wall 54 fastened S «W can be used, which with the connection and Um- 20 material for the antenna ^ nf ^ Lj α ⁸ x. '· - ^en

environmental conditions of the system is compatible. GewönnIiS is hS JnTZ _t ^{you lst} i ^ChlaSSlg _H ·

The output of the voltage controlled oscillator z. B. an acrylic plastic D ^ ί ^

29 is connected to the two-phase modulator 30, through a KoaSabe % Na, ««

its circuit diagram in FIG. 3 is shown. The mod _u : vertical tab f _{6 or} f an * efnen correspond

lator 30 contains a quartz-controlled oscillator 33, 5 primary radiators coupled S of Lh Ken H

for generating a carrier signal with a constant space between the PIaUe 53 and the wall Ii W

Frequency which extends in parallel via a transformer 35. The exact name dimensions k, r

switched to a diagonal of the diode quad 34 every application ΓηΤί! ιΤ ^{8 lf} H ^r

and in this way symmetrical operation is dependent on ⁸ transmission frequency

of the diode quad 34 guaranteed. The diode quad 30 one

,, gnals during the passage of the »modulation darges.eV)„ n, the The input _{circle d es} Moduhwr, 3 »OhII. a 3 ₅ ^

and 38 operated in the forward direction, which is a very 40 speed of the Wheatsioie Brtif. 1?

low input impedance for the through the oscil- Kap'zitJt M ^ SS ^ ifS ^ *

lator 33 means generated RF signal and whereby I _n another AusRihninorfA ™ λ

this signal coupled to the output connection 45 is the ^ Tj ^^^^^ St

will. If a negative input signal is accommodated on the module housing 49 (Fi l \ L · "" 9 ^e "

latorcingang is pressed, the diodes 37 _{45 are} one for the Seffintenn Vso oassenHen ° n ^ZUgS . ^wise

and 39 operated in the forward direction, which means that it has and has a «W? if «| L? f _u ^ligand Durchmes-

HF signal around! 80 * compared to the case with positive Snarin "sfigtSS ^" ^{8 M 1} ^ "

ver input voltage phase-rotated to the output Each receiver of the AnLlLe ·, α

output connections 45 is given and the antenna 32 is receivedTkann Ina ml 2 ^g uu "

The separation of the non-conductive diodes is Sung SÄ ^ SS! according to the 55 polarization applied to it in the reverse direction d ^^ nSn d _Urch Γ modulation voltage increased. It is seen that the horizontally polarized FM S ™ i Ll £ TT the amount of phase shift of the output transmitters kept small _who the D ^ κΓf ^circular _t ^funk "signal to the terminals 45 becomes independent of the vorzuesS η ρΓ / r F ^ ^{pfangSantenne}

^{The amplitude of the modulation voltage} is 3 to 1 km from Γ J ^nt J ernun g ™ " approximately

The output of the two-phase modulator 30 is connected to a power amplifier with 60 wassicl ^ Ä sufficient ίΰΓε ^ ηΓ f ^ f ^ a power amplifier, which delivers about even when there is an "start ™ £ ^pfa " ^g mW output power. This has been proven for the schens Coronary

A specific embodiment of the subject of the invention according to the Tnsmiiinirm α λτ ■ _L

Stand proven to be sufficient. The output of the BrSe 12 at IiI ^ ₄ ^From l ^chtun i is the power amplifier 31 is connected to a transmitting antenna 6 ₅ uXhalb the ΙΖ ^ Χ ^ Γ ^ Τ ^ , which, as described above, directly using the potentiometer Tfi,? ^ F ^ S " ^lp ? ™ ^door is arranged on the housing 47 (cf. Fig. 1 of the 43? B! * 2 ££ T? I" ^{16 and the control} resistor and S). ^{lg 8} Jin AnSe ⁸ A (output voltage equal to zero).

A rise in the conductor temperature then leads to

Io

an increase in the resistance of the control line associated Wheatstone bridge like the one in FIG. 10, which leads to an asymmetry of the bridge 12 and the bridge 12 shown in FIG . The degree voltage controlled oscillator is placed. The conductor of the control line 10, which is connected to the conductor 11, empirically the temperature extends over the sections a, b and c, can be assigned to the increase in the control line 10 if the current is known Bridge 65 connected lei If the time-dependent mean temperature and ter extends over sections b and c; the conductor connected to the thermal parameters of various segments with bridge 66 extends and sections of the cable route to be monitored io only over section c. The bridges 64, 65 and are known, the temperature can be determined precisely at every desired point of the cable 66 are with the associated voltage-controlled oscilloscope. the mean temperature control line 10 made of copper wire is in one of the sections a, b and c, the Sections b and c typical case, the series resistance of the control line 15 and section c of the cable conductor 11 'corresponds to 10 and of the conductor 11 at 25 ° C about 18 ohms. In chen. The outputs of the voltage-controlled oscillator in this case, for the resistors 13 and 14, 67, 68, 69 are connected to the transmitter 28 with an ent-values of 18 or 15 ohms and for the resistance speaking three-channel transmitter, so that the 15 has a value of 15 Ohms can be chosen. The output of the receiver shows the mean temperature of the three cable sections mentioned in a special embodiment of the invention. The middle one is the device for measuring the mean temperature of each of the individual sections a, b and c temperatures of a number of segments of a cable conductor can be determined from this by simple arithmetic conversion or from segments of several voltages, if the lengths of the connected cable conductors, whose temperature profile is known to each other belonging sections is the same, designed. For example, the mean temperature is the result

To monitor a single cable conductor of the section α can, as shown in FIG. 7 shown, a multi-core
Control line used on the same T (abc) L (abc) - T (bc) L (bc)

Way like a single control line inside the ' W \.' . \ '. _t

Cable is arranged. Fig. 7 shows a quadruple 30 ^L \ ^a ) segmented cable ladder 57 with opposing segments 57 a and 57 c, which from the segments T (x) is the measured mean temperature of the element 57 ft and 57 d - to reduce the skin Section χ and L (x) mean the length of this interval! * Effect through insulation made of coated paper. The whole in Fig. 8 are separated. The conductor 57 is wrapped by a plurality of transmitting devices similar to the insulating layers shown in FIG. The control line 60 are located. As already described above, the housing is located in the core of the segmented conductor 57 in environments with electrical FeI and contains the lines 61, 62 and 63, which are produced separately from the segmented conductor 57, which is preferably made of electrically conductive material. The housing can be made of glass fiber points electrically connected along the cable or a similar fusible material. For each two of these points, the sections of the route covered with a conductive layer can be drawn in the middle. The outputs of the various Wheat temperatures can be determined. 45 Stone bridges can possibly be connected to a single-channel sensor game via a multiplexer known in FIG.

voltage cable contains a multi-core control line (not shown for measuring the average temperatures of several), the individual lines of which on each section of a multi-conductor cable can be provided with a control line at each of the different points marked with an "x" with 50 individual conductors and connected to the current conductor 11 ' and thereby subdivide each of the section boundary points according to the cable route into sections a, b and c. F i g. 8 are electrically connected to this. At the right end of the current conductor 11 'ends in a cable which delimits one of these conductors in each case, cable end closures, not shown in the cited figure, single-channel transmitters can be provided. Closure according to FIG. B. over different frequencies in which the three wires of the control line 10 back. Signals are introduced to a common receiver. Each of the ladder has to be carried with one.

1 sheet of drawings

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Claims (2)

ι 2 cracks of the cable come. In such counter claims: the moisture content is usually very low and subject to unpredictable fluctuations, see above 1. Device for monitoring the mean that projections of the thermal Betnerslängs The temperatures prevailing in a cable section are not 5 with the necessary accuracy durc.iperatur can be performed by means of a direct current source. It is known, for example, that the temperature euur send measuring device, thereby marked landline at individual points of the line network I η et that one can be measured over the length of the through jacket with the help of thermocouples, the measurement of the cable section to be recorded, which means that very precise values are obtained at these points! ■ with the conductor (11) of the cable in thermitone. To get an idea of the temperature scheme and only at the end of the section in elekverlauf over a longer cable section make xvi Irish contact with control line (10), but it would be necessary to enter a large number! temperature-dependent conductivity is provided by thermocouples, but what mn and together with the conductor (H) a 15 a considerable effort and still with the Branch of the Wheatstone Bridge (12) forms, need to interpolations would be connected, which, together with one of the measured values (It is also known, the temperatures of transition voltages) of the Wheatstone Bridge land lines with the help of tables under Access (12) emitting transmitter (28) in an electrical basic setting carried out in the laboratory tric and magnetic fields shielding 20 measurements of certain cable properties, aui Housing (47) is arranged. 'Ground measured soil as well as the weather 2. Device according to claim 1, characterized in that there are conditions along a respective cable section indicates that the direct current source (21) tes to be determined. In this way, however, you can has a transformer whose primary does not determine exact instantaneous temperature values winding of the conductor (11) and its se- as. secondary winding (24) with a circuit (23), on the other hand, the object of the invention to rectify the branched-off alternating reasons to create a device with which the Electricity and generation of the desired equal instantaneous values of the mean temperature for longer Stroms is connected. Cable runs continuously with relatively one