CN202166481U - Cable temperature collecting circuit based on transient thermal circuit of single core cable - Google Patents
Cable temperature collecting circuit based on transient thermal circuit of single core cable Download PDFInfo
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- CN202166481U CN202166481U CN2011201961703U CN201120196170U CN202166481U CN 202166481 U CN202166481 U CN 202166481U CN 2011201961703 U CN2011201961703 U CN 2011201961703U CN 201120196170 U CN201120196170 U CN 201120196170U CN 202166481 U CN202166481 U CN 202166481U
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Abstract
The utility model provides a cable temperature collecting circuit based on a transient thermal circuit of a single core cable. In the utility model, a main chip U1 is adopted as a main body. A pin 7 of the main chip U1 is a power source of the main chip U1. A pin 4 is a grounding terminal of the main chip U1. A pin 2 connects with one end of a resistor R2 and one end of a resistor R3. The other end of the resistor R2 connects with a pin 6 and the other end of the resistor R3 connects with one end of a variable resistor R4. The other end of the variable resistor R4 connects with a signal ground. A pin 3 of the main chip connects with one end a temperature-sensing resistor R1 and one end of a voltage-regulator tube D1. The other end of the voltage-regulator tube is a +15V power source while the other end of the voltage-regulator tube D1 is the signal ground. A pin 8 of the main chip U1 connects with one end of a capacitor C1 while the other end of the capacitor C1 is the signal ground. One end of a temperature-sensing resistor R5 connects the +15V power source while the other end of the temperature-sensing resistor R5 connects with a voltage-regulator tube D2 and one end of a variable resistor RP as well. The other end of the voltage-regulator tube D2 and the variable resistor RP connect with the signal ground, the temperature-sensing resistor R5 and the temperature-sensing resistor R5. A common terminal of a variable resistor RP is an output terminal - of the cable temperature collecting circuit. The cable temperature collecting circuit based on the transient thermal circuit of the single core cable can detect the temperature of a core of a cable.
Description
Technical field
The present invention relates to the cable detection field, particularly a kind of cable temperature Acquisition Circuit based on the single core cable Transient Thermal Circuit.
Background technology
At present, the measurement of the core temperature of cable, conductor temperature is the key factor of reflection cable running status, thereby is necessary to realize the monitoring to it.In the reality the direct measurement that moves the cable conductor temperature is difficult to realize that the normal calculation mode that adopts is obtained in the engineering, and the feasible accurate Calculation to conductor temperature of cable external factor complicated and changeable is also very difficult.
Summary of the invention
In order to overcome the deficiency of above-mentioned prior art, the invention provides a kind of cable temperature Acquisition Circuit based on the single core cable Transient Thermal Circuit.
In order to achieve the above object, the cable temperature Acquisition Circuit based on the single core cable Transient Thermal Circuit provided by the invention.This circuit is the main body with master chip U1; 7 pin of master chip U1 are the power supply of master chip U1, and 4 pin are the earth terminal of master chip U1, and 2 pin connect resistance R 2 and resistance R 3 one ends; The other end of resistance R 2 connects 6 pin of master chip U1; Be the output terminal "+" of cable temperature Acquisition Circuit, the other end of resistance R 3 connects the end of variohm R4, and the other end of variohm R4 connects signal ground; 3 pin of master chip U1 are connected to the end of temperature sensitive resister R1 and stabilivolt D1, and the other end of temperature sensitive resister R1 is+the 15V power supply that the other end of stabilivolt D1 is a signal ground; 8 pin of master chip U1 are connected to capacitor C 1, and the other end of capacitor C 1 is a signal ground; End connection+15V the power supply of temperature sensitive resister R5; The other end connects adjustable stabilivolt D2; Be connected to the end of variohm RP simultaneously; The other end of adjustable stabilivolt D2 and variohm RP is connected signal ground, and temperature sensitive resister R5 and adjustable stabilivolt D2, the common port of variohm RP are the output terminal "-" of cable temperature Acquisition Circuit; Wherein, temperature sensitive resister R1 and temperature sensitive resister R5 are temperature sensitive resister PT100; Said master chip U1 is LM324; Said stabilivolt D1 is LM336; Said adjustable stabilivolt D2 is LM335.
The present invention passes through the measurement to the surface temperature of cable; Can detect cable core (various ship electricity, the copper of shore connection cable, aluminium core) temperature; So that calculate the resistivity of cable core, calculate the power consumption of cable, the while also provides significant data to the residual life of cable.To these data handle with analysis-by-synthesis after; Size and variation tendency according to its numerical value; Can make the reliability of cable and judge and the residual life of cable is made a prediction, thereby the fault of can early detection hiding can provide the operation of early warning or regulation in case of necessity.
Description of drawings
Fig. 1 is based on the cable temperature Acquisition Circuit figure of single core cable Transient Thermal Circuit.
Fig. 2 only considers the cable Re Lutu that conductor current changes.
Fig. 3 only considers the cable equivalence Re Lutu that conductor current changes.
Fig. 4 only considers the cable equivalence Re Lutu that skin temperature changes.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is elaborated.
One, circuit structure
With reference to Fig. 1, in the cable temperature Acquisition Circuit based on the single core cable Transient Thermal Circuit of present embodiment.This circuit is the main body with master chip U1; 7 pin of master chip U1 are the power supply of master chip U1, and 4 pin are the earth terminal of master chip U1, and 2 pin connect resistance R 2 and resistance R 3 one ends; The other end of resistance R 2 connects 6 pin of master chip U1; Be the output terminal "+" of cable temperature Acquisition Circuit, the other end of resistance R 3 connects the end of variohm R4, and the other end of variohm R4 connects signal ground; 3 pin of master chip U1 are connected to the end of temperature sensitive resister R1 and stabilivolt D1, and the other end of temperature sensitive resister R1 is+the 15V power supply that the other end of stabilivolt D1 is a signal ground; 8 pin of master chip U1 are connected to capacitor C 1, and the other end of capacitor C 1 is a signal ground; End connection+15V the power supply of temperature sensitive resister R5; The other end connects adjustable stabilivolt D2; Be connected to the end of variohm RP simultaneously; The other end of adjustable stabilivolt D2 and variohm RP is connected signal ground, and temperature sensitive resister R5 and adjustable stabilivolt D2, the common port of variohm RP are the output terminal "-" of cable temperature Acquisition Circuit; Wherein, temperature sensitive resister R1 and temperature sensitive resister R5 are temperature sensitive resister PT100; Said master chip U1 is LM324; Said stabilivolt D1 is LM336; Said adjustable stabilivolt D2 is LM335.
Two, theoretical analysis
On the basis of cable sheath temperature monitoring, set up the mathematical model of single core cable Transient Thermal Circuit; Derive respectively and only consider that electric current changes and only consider that skin temperature changes the transient state temperature rise recursion formula under two kinds of situation, and then derive the complete Superposition Formula of single core cable transient state temperature; And adopt classical 4 rank Runge2Kutta methods to find the solution differential equation set of calculated cable body temperature.Carried out single core cable transient state temperature rise test in the testing ground, and result of calculation and the temperature data that test records have been carried out contrast verification.The result shows, has higher precision based on the single core cable transient state temperature computation of cable sheath temperature monitoring, can be used for the aspects such as temperature control, cable status monitoring and fault pre-alarming thereof in the single core cable actual motion.
1.1 only consider the cable Transient Thermal Circuit that conductor current changes
Suppose that skin temperature is invariable, conductor dbus is during with transient current, and cable Transient Thermal Circuit illustraton of model is as shown in Figure 2.Among Fig. 2, Wc and Ws are respectively the hot-fluid in conductor and the protective metal shell, they all with square being directly proportional of conductor current; Ti and Tw are respectively the thermal resistance of insulation course and outer jacket; Qc, Qi, Qs, Qw are respectively the thermal capacitance of conductor, insulation course, protective metal shell, outer jacket from the inside to the outside; θ c, θ s, θ w0 are respectively conductor temperature, protective metal shell temperature and skin temperature.Wherein θ c, θ s are amounts to be asked, and each several part thermal resistance and thermal capacitance can obtain according to the cable material calculation of parameter.The insulation course of cable and the thermal resistance of outer jacket and thermal capacitance are distributed parameters, bring very big difficulty to calculating, because cable operations staff and be indifferent to the inner distribution with the outer jacket internal heat of insulation, so can do following simplification for Fig. 2:
1) distributes Qi and Qw toward its both sides adjacent structure by allocation proportion factor p and p ';
2) effect of protective metal shell hot-fluid Ws is passed through coefficient qs equivalence in corresponding thermal resistance and thermal capacitance parameter;
3) ignore the outside thermal capacitance of outer jacket.Thereby obtain the equivalent hot road of Fig. 2, shown in Fig. 3.Among Fig. 3,
Q1=Qc+pQi; Q2=(1-p) Qc+(Qs+p ' Qw)/qs; P and p ' according to the node current method, only consider that the pairing node heat flow equation of Transient Thermal Circuit that conductor current changes does by the corresponding relation of Re Lu and circuit
Make θ c=y1, θ s=z1, t=x then has
In the formula,
.Differential equation group (2) is in order to calculate the cable transient temperature rise of only considering that conductor current changes.
1.2 only consider the cable Transient Thermal Circuit supposition skin temperature that skin temperature changes an increment Delta θ w is arranged on the basis of initial value θ w0, and no current in the conductor, copy in 1.1 joints method directly to set up equivalent hot road model, shown in Fig. 4.According to Fig. 4, list and only consider that the Transient Thermal Circuit corresponding nodes heat flow equation that skin temperature changes does
Make θ c=y2 equally, θ s=z2, t=x then has:
In the formula,
.Differential equation group (4) is in order to calculate the cable transient state temperature rise of only considering that skin temperature changes.
2.Runge-Kutta method is found the solution
Can know that by formula (2) and formula (4) what the temperature rise of calculating conductor transient state was used all is the differential equation of first order group, if directly ask the calculated amount of analytic solution will be very big.And the system of equations of differentiating commonly used be numerical solution, this paper adopts classical 4 rank Runge2Kut ta methods, its precision can satisfy requirement of engineering.For arbitrary ordinary differential equation group, suppose that its initial-value problem is:
4 rank Runge2Kut ta formula have following form:
In the formula, n=0,1,2;
Formula (6) is one group of recursion formula about y and z; Wherein h is a time step, according to xn y n and z n value constantly, by formula (7) calculating K 1～K4; L1～L4, substitution formula (6) get final product xn+1 numerical solution yn+1 constantly and z n+1.With Runge2Kut ta method (2) are found the solution; When finding only to consider that conductor current changes; In the stepping type of xn conductor temperature y1 n and protective metal shell temperature z 1 n constantly except containing initial value constant θ w0; Also comprising with conductor hot-fluid Wc is the function item of variable, uses f n (Wc) and gn (Wc) expression respectively, and then the general formula of y1 n and z 1 n can be expressed as
In like manner use Runge2Kut ta method that formula (4) is found the solution; When finding only to consider that skin temperature changes; In the stepping type of xn conductor temperature y 2 n and protective metal shell temperature z 2 n constantly except containing initial value constant θ w0; Also comprising with protective metal shell temperature variation Δ θ w is the function item of variable, uses un (Δ θ w) and vn (Δ θ w) expression respectively, and then the general formula of y2 n and z 2 n can be expressed as
Utilize Runge2Kut ta method to find the solution differential equation group; Only considered that conductor current changes and only considered that skin temperature changes the cable transient state temperature rise calculating general formula under two kinds of situation; Because two temperature rise general formulas all are on the basis of same skin temperature initial value θ w0, to obtain, and the xn in two general formulas all represents synchronization, so the temperature rise that causes for two independent factors with generation constantly; Can directly carry out linear superposition, thereby further obtain the transient state temperature of cable conductor and protective metal shell.
Above content is to combine optimal technical scheme to the further explain that the present invention did, and can not assert that the practical implementation of invention only limits to these explanations.Under the present invention, the those of ordinary skill of technical field, under the prerequisite that does not break away from design of the present invention, simple deduction and replacement can also be made, all protection scope of the present invention should be regarded as.
Claims (1)
1. cable temperature Acquisition Circuit based on the single core cable Transient Thermal Circuit; It is characterized in that said cable temperature Acquisition Circuit is the main body with master chip U1,7 pin of master chip U1 are the power supply of master chip U1; 4 pin are the earth terminal of master chip U1; 2 pin connect resistance R 2 and resistance R 3 one ends, and the other end of resistance R 2 connects 6 pin of master chip U1, the i.e. output terminal "+" of cable temperature Acquisition Circuit; The other end of resistance R 3 connects the end of variohm R4, and the other end of variohm R4 connects signal ground; 3 pin of master chip U1 are connected to the end of temperature sensitive resister R1 and stabilivolt D1, and the other end of temperature sensitive resister R1 is+the 15V power supply that the other end of stabilivolt D1 is a signal ground; 8 pin of master chip U1 are connected to capacitor C 1, and the other end of capacitor C 1 is a signal ground; End connection+15V the power supply of temperature sensitive resister R5; The other end connects adjustable stabilivolt D2; Be connected to the end of variohm RP simultaneously; The other end of adjustable stabilivolt D2 and variohm RP is connected signal ground, and temperature sensitive resister R5 and adjustable stabilivolt D2, the common port of variohm RP are the output terminal "-" of cable temperature Acquisition Circuit; Wherein, temperature sensitive resister R1 and temperature sensitive resister R5 are temperature sensitive resister PT100; Said master chip U1 is LM324; Said stabilivolt D1 is LM336; Said adjustable stabilivolt D2 is LM335.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011201961703U CN202166481U (en) | 2011-06-13 | 2011-06-13 | Cable temperature collecting circuit based on transient thermal circuit of single core cable |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011201961703U CN202166481U (en) | 2011-06-13 | 2011-06-13 | Cable temperature collecting circuit based on transient thermal circuit of single core cable |
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| CN202166481U true CN202166481U (en) | 2012-03-14 |
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| CN2011201961703U Expired - Fee Related CN202166481U (en) | 2011-06-13 | 2011-06-13 | Cable temperature collecting circuit based on transient thermal circuit of single core cable |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102928109A (en) * | 2012-10-25 | 2013-02-13 | 重庆长安汽车股份有限公司 | Signal collecting circuit |
| CN104062323A (en) * | 2014-06-06 | 2014-09-24 | 西安理工大学 | Method for measuring contact resistance on line |
| CN107228994A (en) * | 2017-04-17 | 2017-10-03 | 国网浙江省电力公司舟山供电公司 | A kind of high-voltage alternating cable duty cycle heating means |
-
2011
- 2011-06-13 CN CN2011201961703U patent/CN202166481U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102928109A (en) * | 2012-10-25 | 2013-02-13 | 重庆长安汽车股份有限公司 | Signal collecting circuit |
| CN104062323A (en) * | 2014-06-06 | 2014-09-24 | 西安理工大学 | Method for measuring contact resistance on line |
| CN107228994A (en) * | 2017-04-17 | 2017-10-03 | 国网浙江省电力公司舟山供电公司 | A kind of high-voltage alternating cable duty cycle heating means |
| CN107228994B (en) * | 2017-04-17 | 2019-12-06 | 国网浙江省电力公司舟山供电公司 | High-voltage alternating-current cable load cyclic heating method |
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Granted publication date: 20120314 Termination date: 20140613 |
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