CN105973499A - Method for measuring temperature of conductor externally covered by insulation material - Google Patents

Abstract

The invention discloses a method for measuring the temperature of a conductor externally covered by insulation material. The method comprises the following steps: establishing a heat transfer equation of the conductor under a heat stable state, and establishing the heat transfer equation based on heat flux balance and with heat radiation of the conductor body to the insulation layer being neglected; and measuring environment space temperature of the conductor and temperature of conductor insulation layer outer wall and obtaining parameter values and carrying out calculating through the heat transfer equation to obtain the temperature of the conductor body. According to the method for measuring the temperature of the conductor externally covered by the insulation material, the heat transfer equation is established by utilizing energy conservation laws in thermodynamics and based on heat flux balance of the conductor under the heat stable state, and the temperature of the conductor body is obtained indirectly by measuring the environment space temperature of the conductor and the temperature of the conductor insulation layer outer wall; and measurement reliability is high.

Description

A kind of thermometry being cladded with insulant conductor

Technical field

The present invention relates to conductor temperature field of measuring technique, particularly relate to a kind of temperature being cladded with insulant conductor and survey Metering method.

Background technology

Measurement to current－carrying conductor body temperature, can not only realize the prediction of current-carrying capacity actual to conductor, and can protect The outer insulating layer coating of conductor does not cause aging because of overheated, reduces its working life.Therefore, to the temperature being cladded with insulant conductor Degree is measured, and has great engineer applied and is worth.

At present, to this kind of conductors being cladded with insulant such as power cable, solid insulation switch cabinet water conservancy diversion rows, obtain it and lead The method of body body temperature is: use the temperature measuring equipment such as infrared radiation thermometer, wireless temperature measuring instrument to measure the indoor residing for conductor The variant space temperature measuring point in space, then based on measuring the space temperature of point, rule of thumb estimate conductor temperature, as The temperature value of conductor body.Obviously, the conductor temperature that this measuring method obtains not is the actual temperature of reflection conductor body Value.

Therefore, the most effectively, reliably obtain the conductor temperature being cladded with insulant conductor, just become one and urgently solve Problem certainly.

Summary of the invention

It is an object of the invention to provide a kind of thermometry being cladded with insulant conductor, utilize the energy in thermodynamics Amount conservation rule, sets up heat transfer equation based on conductor heat flow density balance under hot stable state, indirectly measures acquisition conductor body Temperature, Measurement reliability is high.

For achieving the above object, the present invention provides following technical scheme:

A kind of thermometry being cladded with insulant conductor, including:

Set up conductor heat transfer equation under hot stable state, balance based on heat flow density and ignore conductor body to insulating barrier Heat radiation sets up described heat transfer equation, described heat transfer equation particularly as follows:

$\frac{t_0-t_1}{\underset{i=1}{\overset{n}{\Σ}}\frac{1}{2{\mathrm{\π\λ}}_{i-1}}ln\frac{r_i}{r_{i-1}}}=h(t_1-t_2)+\mathrm{\ϵ}\mathrm{\σ}(t_1^4-t_2^4),$

Wherein, t0 is conductor body temperature, and t1 is the temperature of insulating layer of conductor outer wall, and t2 is environment space temperature, λ_i-1For The heat conductivity of the i-th-1 layer insulant of conductor, λ₀For the heat conductivity of conductor body, r_iFor i-th layer of insulant of conductor half Footpath, r_i-1For the radius of the i-th-1 layer insulant of conductor, r₀For the radius of conductor body, h is between insulating layer of conductor and air Complex heat transfer coefficient, ε is the thermal emissivity of insulating layer of conductor, and σ is black body radiation constant, and n is the layer of conductor insulation material layer Number；

Measure the environment space temperature residing for conductor and the temperature of insulating layer of conductor outer wall, and obtain each parameter value, pass through Described heat transfer equation calculates the temperature obtaining conductor body.

Alternatively, the environment space temperature residing for conductor is measured particularly as follows: measure the space temperature of distance conductor predeterminable range Degree, as the environment space temperature residing for conductor.

Alternatively, described predeterminable range is more than or equal to 15cm.

Alternatively, the temperature of insulating layer of conductor outer wall is measured particularly as follows: temperature sensor be arranged on outside insulating layer of conductor Wall measures.

Alternatively, the computing formula of the complex heat transfer coefficient h between described insulating layer of conductor and air is:

H=1/R；

$R=\underset{i=1}{\overset{n}{\Σ}}\frac{1}{2{\mathrm{\π\λ}}_{i-1}}\ln \frac{r_i}{r_{i-1}}+\frac{1}{2{\mathrm{\πr}}_n{h}_n};$

Wherein, R is the thermal resistance value of insulating layer of conductor, λ_i-1For the heat conductivity of the i-th-1 layer insulant of conductor, λ₀For leading The heat conductivity of body body, r_iFor the radius of i-th layer of insulant of conductor, r_i-1For the radius of the i-th-1 layer insulant of conductor, r₀ For the radius of conductor body, h_nFor the heat transfer coefficient of conductor n-th layer insulant, r_nFor the radius of conductor n-th layer insulant, n The number of plies for conductor insulation material layer.

Alternatively, if being cladded with insulant conductor there is 1 layer of insulant, between the most described insulating layer of conductor and air The computing formula of complex heat transfer coefficient h is:

H=1/R；

$R=\frac{1}{2{\mathrm{\π\λ}}_0}\ln \frac{r_1}{r_0}+\frac{1}{2{\mathrm{\πr}}_1{h}_1};$

Wherein, R is the thermal resistance value of insulating layer of conductor, λ₀For the heat conductivity of conductor body, r₀For the radius of conductor body, r₁For the radius of insulant, h₁Heat transfer coefficient for conductor insulation material layer.

By technique scheme it can be seen that the thermometry being cladded with insulant conductor provided by the present invention, Utilize the Energy conservation law in thermodynamics, hot stable state lower conductor body, insulating layer of conductor and and environment space between Conduction of heat, natural heat-exchange and heat radiation follow Energy conservation law, i.e. amount of thermal conduction between conductor body and insulating barrier, heat Amount of radiation, with insulating layer of conductor and the amount of thermal conduction of environment space, thermal exposure balance, sets up heat transfer model；It is right additionally to consider In conductor, the thermal exposure understood between conductor body and insulating barrier according to Boltzmann law when hot stable state is significantly less than heat Conductive quantity, is based on conduction of heat, therefore in the heat transfer equation describing heat transfer model, ignores the conductor body heat to insulating barrier Radiative process.And heat transfer equation based on heat is converted to the heat transfer equation of heat flow density, set up by conductor body according to this Temperature, the temperature of insulating layer of conductor outer wall and the heat transfer equation described by environment space temperature.After setting up heat transfer equation, logical Cross the environment space temperature measured residing for the temperature of insulating layer of conductor outer wall and conductor, and determine each parameter in heat transfer equation Value, and then the temperature obtaining conductor body is calculated by heat transfer equation.

The present invention is cladded with the thermometry of insulant conductor, builds based on conductor heat flow density balance under hot stable state Write a biography Biot-fourier equation, by measuring the environment space temperature residing for the temperature of insulating layer of conductor outer wall and conductor, by set up Heat transfer equation achieves measures the temperature obtaining conductor body indirectly, and Measurement reliability is high.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to Other accompanying drawing is obtained according to these accompanying drawings.

The flow chart of a kind of thermometry being cladded with insulant conductor that Fig. 1 provides for the embodiment of the present invention；

Fig. 2 is the layout schematic diagram at insulation looped network in-cabinet temperature sensor；

Fig. 3 is the schematic diagram measuring busbar conductor insulating barrier outside wall temperature.

Detailed description of the invention

For the technical scheme making those skilled in the art be more fully understood that in the present invention, real below in conjunction with the present invention Execute the accompanying drawing in example, the technical scheme in the embodiment of the present invention is clearly and completely described, it is clear that described enforcement Example is only a part of embodiment of the present invention rather than whole embodiments.Based on the embodiment in the present invention, this area is common The every other embodiment that technical staff is obtained under not making creative work premise, all should belong to present invention protection Scope.

Refer to Fig. 1, a kind of thermometry being cladded with insulant conductor provided for the embodiment of the present invention, bag Include:

S1: set up conductor heat transfer equation under hot stable state, balances based on heat flow density and ignores conductor body to insulation Layer heat radiation set up described heat transfer equation, described heat transfer equation particularly as follows:

$\frac{t_0-t_1}{\underset{i=1}{\overset{n}{\Σ}}\frac{1}{2{\mathrm{\π\λ}}_{i-1}}ln\frac{r_i}{r_{i-1}}}=h(t_1-t_2)+\mathrm{\ϵ}\mathrm{\σ}(t_1^4-t_2^4),$

Wherein, t0 is conductor body temperature, and t1 is the temperature of insulating layer of conductor outer wall, and t2 is environment space temperature, λ_i-1For The heat conductivity of the i-th-1 layer insulant of conductor, λ₀For the heat conductivity of conductor body, r_iFor i-th layer of insulant of conductor half Footpath, r_i-1For the radius of the i-th-1 layer insulant of conductor, r₀For the radius of conductor body, h is between insulating layer of conductor and air Complex heat transfer coefficient, ε is the thermal emissivity of insulating layer of conductor, and σ is black body radiation constant, and n is the layer of conductor insulation material layer Number, n >=1；

S2: measure the environment space temperature residing for conductor and the temperature of insulating layer of conductor outer wall, and obtain each parameter value is logical Cross described heat transfer equation and calculate the temperature obtaining conductor body.

As shown in the above, the thermometry being cladded with insulant conductor that the embodiment of the present invention provides, utilize Energy conservation law in thermodynamics, hot stable state lower conductor body, insulating layer of conductor and and environment space between heat biography Lead, natural heat-exchange and heat radiation follow Energy conservation law, i.e. amount of thermal conduction between conductor body and insulating barrier, heat radiation Amount, with insulating layer of conductor and the amount of thermal conduction of environment space, thermal exposure balance, sets up heat transfer model；Additionally consider for leading Body, the thermal exposure understood between conductor body and insulating barrier according to Boltzmann law when hot stable state is significantly less than conduction of heat Amount, is based on conduction of heat, therefore in the heat transfer equation describing heat transfer model, ignores the conductor body heat radiation to insulating barrier Process.And heat transfer equation based on heat is converted to the heat transfer equation of heat flow density, according to this set up by conductor body temperature, Heat transfer equation described by the temperature of insulating layer of conductor outer wall and environment space temperature.After setting up heat transfer equation, by surveying Environment space temperature residing for the temperature of amount insulating layer of conductor outer wall and conductor, and determine each parameter value in heat transfer equation, And then the temperature of acquisition conductor body is calculated by heat transfer equation.

The present embodiment is cladded with the thermometry of insulant conductor, based on conductor heat flow density balance under hot stable state Set up heat transfer equation, by measuring the environment space temperature residing for the temperature of insulating layer of conductor outer wall and conductor, by setting up Heat transfer equation achieve and indirectly measure the temperature obtaining conductor body, Measurement reliability is high.

With a specific embodiment, the present invention is cladded with the thermometry of insulant conductor below to be described in detail. In the present embodiment specifically as a example by solid insulation ring main unit busbar conductor, measure its current－carrying conductor temperature.

(1): set up the heat transfer equation under hot stable state.

In Practical Project when ring main unit operation reaches stable state, the heat transfer equation of solid insulation ring main unit busbar conductor describes For: Φ=Aq, wherein Φ is for always transmitting heat, and A is that heat conducting cross-sectional amasss, and q is heat flow density.

For solid insulation ring main unit busbar conductor, consider when being in hot stable state to ignore the conductor body hot spoke to insulating barrier Being emitted through journey, therefore obtaining its formula for entrepreneurship followed is that the conductor body amount of thermal conduction with insulating barrier is equal to insulating barrier and environment The natural heat-exchange amount in space and the insulating barrier thermal exposure sum to environment space, but in Practical Project, Φ is difficult to record, because of This is converted to the relational expression of heat flow density q, can be greatly simplified amount of calculation.

In the present embodiment, ring main unit busbar conductor has single-layer insulation material.The heat transfer equation obtained is:

$q=\frac{t_0-t_1}{\frac{1}{2{\mathrm{\π\λ}}_0}\ln \frac{r_1}{r_0}}=h(t_1-t_2)+\mathrm{\ϵ}\mathrm{\σ}(t_1^4-t_2^4)$

Wherein, t0 is conductor body temperature, and t1 is the temperature of insulating layer of conductor outer wall, and t2 is environment space temperature, λ₀For The heat conductivity of conductor body, r₁For the radius of conductor insulation material, r₀Referring to the radius of conductor body, h is insulating layer of conductor outer wall And the complex heat transfer coefficient between air, ε is the thermal emissivity of insulating layer of conductor, and σ is black body radiation constant.

(2): measure environment space temperature t2 residing for ring main unit busbar conductor.

In busbar room, busbar conductor is as a pyrotoxin in solid insulation ring main unit, is passed by the temperature of indoor location The interior space temperature that sensor records to reflect space temperature the most truly, and therefore the installation site of temperature sensor to be closed Reason, measures the space temperature of distance thermal source conductor predeterminable range, as the environment space temperature residing for conductor in the present embodiment.

Refer to shown in Fig. 2, specifically will be apart from the arbitrfary point outside busbar conductor (thermal source) 15cm as temperature in the present embodiment Degree measures point, arranges temperature sensor 1 thermometric, and the temperature value recorded is as environment space temperature.

(3): measure temperature t1 of insulating layer of conductor outer wall.It is specially and temperature sensor is arranged on insulating layer of conductor outer wall Carry out temperature survey, specifically refer to shown in Fig. 3, temperature sensor 1 is arranged and on the insulating barrier outer wall of busbar conductor, measures temperature Degree, measures temperature t1 obtaining insulating layer of conductor outer wall.

(4): obtain each parameter value, including the heat conductivity λ of conductor body₀, the heat conductivity λ of conductor insulation material₁, lead The radius r of body insulant₁, the radius r of conductor body₀, complex heat transfer coefficient h between insulating layer of conductor outer wall and air, leads Thermal emissivity ε of body insulating barrier, black body radiation constant σ.

Wherein, according to conductor, the respective attribute of conductor insulation layer material, the heat conductivity λ of conductor is determined₀, conductor insulation The heat conductivity λ of material₁And thermal emissivity ε of insulating layer of conductor, acquisition of can tabling look-up.Radius, conductor for conductor body are exhausted The radius of edge layer outer wall can measure acquisition.Such as, the conductor body of general busbar conductor is copper, and insulating barrier is epoxy resin, Can be by acquisition copper, the heat conductivity of epoxy resin of tabling look-up.

Can not directly obtain for the complex heat transfer coefficient h between insulating layer of conductor and air, can be by the following method Calculating and obtain, specific formula for calculation is:

H=1/R；

$R=\underset{i=1}{\overset{n}{\Σ}}\frac{1}{2{\mathrm{\π\λ}}_{i-1}}\ln \frac{r_i}{r_{i-1}}+\frac{1}{2{\mathrm{\πr}}_n{h}_n};$

Wherein, R is the thermal resistance value of insulating layer of conductor, λ_i-1For the heat conductivity of the i-th-1 layer insulant of conductor, λ₀For leading The heat conductivity of body body, r_iFor the radius of i-th layer of insulant of conductor, r_i-1For the radius of the i-th-1 layer insulant of conductor, r₀ For the radius of conductor body, h_nFor the heat transfer system of conductor n-th layer insulant, the namely heat transfer of conductor outermost layer insulant Coefficient, r_nFor the radius of conductor n-th layer insulant, h_n=λ_n/r_n；N is the number of plies of conductor insulation material layer, n >=1.

In insulating barrier diabatic process, thermal resistance comprises two parts resistance, and one is that the heat caused by boundary region hinders referred to as Surface resistance of heat transfer R_s1, another part is thermal-conduction resistance R that heat transmits at insulating barrier_cd, so thermal resistance value R should be both sums, I.e. R=R_s1+R_cd.In this computing formula,Represent thermal-conduction resistance part,Represent surface resistance of heat transfer part.

Busbar conductor to be measured in the present embodiment has one layer of insulant, therefore insulating layer of conductor outer wall and air Between the computing formula of complex heat transfer coefficient h be:

H=1/R；

$R=\frac{1}{2{\mathrm{\π\λ}}_0}\ln \frac{r_1}{r_0}+\frac{1}{2{\mathrm{\πr}}_1{h}_1};$

Wherein, R is the thermal resistance value of insulating layer of conductor, r₀For the radius of conductor body, λ₀For the heat conductivity of conductor body, r₁For the radius of insulant, h₁For the heat transfer coefficient of conductor insulation material layer, h₁=λ₁/r₁。

(5): temperature data and each parameter value are substituted in heat transfer equation, solving equation, thus it is calculated conductor body Temperature t0.

In practical engineering application, according to the heat transfer equation of above-mentioned solid insulation ring main unit busbar conductor, can set up and lead Function expression between body body temperature t0, temperature t1 of insulating layer of conductor outer wall and environment space temperature t2, and set Each parameter value, it is only necessary to look into functional relationship table according to t1, the t2 recorded and just can immediately arrive at the temperature of conductor body.Functional relationships It is that table can be obtained the most in advance by calculated off line formula, convenient utilization in Practical Project, improve work Make efficiency.

It should be noted that the temperature sensor used is not done particular restriction in the present embodiment, its certainty of measurement exists In error allowed band, actual demands of engineering can be met, equipment cost can be reduced, improve the market competition of product Power.

Therefore, the present invention is cladded with the thermometry of insulant conductor, by the analysis to temperature gradient field, utilizes The special arrangement of temperature sensor and thermal conduction study formula realize, to the indirect measurement specifying current－carrying conductor body temperature, measuring reliable Property high.Overcome prior art to be cladded with insulant current－carrying conductor body temperature measure not accurate enough, can not be reflected it The drawback of actual temperature.

Above a kind of thermometry being cladded with insulant conductor provided by the present invention is described in detail. Principle and the embodiment of the present invention are set forth by specific case used herein, and the explanation of above example is simply used In helping to understand method and the core concept thereof of the present invention.It should be pointed out that, for those skilled in the art, Under the premise without departing from the principles of the invention, it is also possible to the present invention is carried out some improvement and modification, these improve and modify also Fall in the protection domain of the claims in the present invention.

Claims (6)

1. the thermometry being cladded with insulant conductor, it is characterised in that including:

Set up conductor heat transfer equation under hot stable state, balance based on heat flow density and ignore the conductor body hot spoke to insulating barrier Penetrate and set up described heat transfer equation, described heat transfer equation particularly as follows:

$\frac{t_0-t_1}{\underset{i=1}{\overset{n}{\Σ}}\frac{1}{2{\mathrm{\π\λ}}_{i-1}}\ln \frac{r_i}{r_{i-1}}}=h(t_1-t_2)+\mathrm{\ϵ}\mathrm{\σ}(t_1^4-t_2^4),$

Wherein, t0 is conductor body temperature, and t1 is the temperature of insulating layer of conductor outer wall, and t2 is environment space temperature, λ_i-1For conductor The heat conductivity of the i-th-1 layer insulant, λ₀For the heat conductivity of conductor body, r_iFor the radius of i-th layer of insulant of conductor, r_i-1For the radius of the i-th-1 layer insulant of conductor, r₀For the radius of conductor body, h is combining between insulating layer of conductor and air Closing heat transfer coefficient, ε is the thermal emissivity of insulating layer of conductor, and σ is black body radiation constant, and n is the number of plies of conductor insulation material layer；

Measure the environment space temperature residing for conductor and the temperature of insulating layer of conductor outer wall, and obtain each parameter value, by described Heat transfer equation calculates the temperature obtaining conductor body.

2. measuring method as claimed in claim 1, it is characterised in that measure the environment space temperature residing for conductor particularly as follows: Measure the space temperature of distance conductor predeterminable range, as the environment space temperature residing for conductor.

3. measuring method as claimed in claim 2, it is characterised in that described predeterminable range is more than or equal to 15cm.

4. measuring method as claimed in claim 1, it is characterised in that measure the temperature of insulating layer of conductor outer wall particularly as follows: incite somebody to action Temperature sensor is arranged on insulating layer of conductor outer wall and measures.

5. measuring method as claimed in claim 1, it is characterised in that the complex heat transfer between described insulating layer of conductor and air The computing formula of coefficient h is:

H=1/R；

$R=\underset{i=1}{\overset{n}{\Σ}}\frac{1}{2{\mathrm{\π\λ}}_{i-1}}\ln \frac{r_i}{r_{i-1}}+\frac{1}{2{\mathrm{\πr}}_n{h}_n};$

Wherein, R is the thermal resistance value of insulating layer of conductor, λ_i-1For the heat conductivity of the i-th-1 layer insulant of conductor, λ₀For conductor body Heat conductivity, r_iFor the radius of i-th layer of insulant of conductor, r_i-1For the radius of the i-th-1 layer insulant of conductor, r₀For conductor The radius of body, h_nFor the heat transfer coefficient of conductor n-th layer insulant, r_nFor the radius of conductor n-th layer insulant, n is conductor The number of plies of insulation material layer.

6. measuring method as claimed in claim 5, it is characterised in that if being cladded with insulant conductor there is 1 layer of insulant, The computing formula of the complex heat transfer coefficient h between the most described insulating layer of conductor and air is:

H=1/R；

$R=\frac{1}{2{\mathrm{\π\λ}}_0}\ln \frac{r_1}{r_0}+\frac{1}{2{\mathrm{\πr}}_1{h}_1};$

Wherein, R is the thermal resistance value of insulating layer of conductor, λ₀For the heat conductivity of conductor body, r₀For the radius of conductor body, r₁For The radius of insulant, h₁Heat transfer coefficient for conductor insulation material layer.