CN104569320A - Method of measuring water content in insulated paper by applying acid value and water content in insulating oil - Google Patents

Abstract

The invention relates to a method of measuring water content in an insulated paper by applying an acid value and water content in insulating oil. The method sequentially comprises the following steps: (a) taking insulating oil of an oil-immersed power transformer in working, and determining temperature T of the insulating oil in real time; (b) putting a part of the insulating oil after the temperature is determined into a Karl Fischer titrator, and measuring the water content Woil in the insulating oil; (c) putting a part of the insulating oil after the temperature is determined into an automatic acid value tester, and measuring the acid value Ac of the insulating oil; and (d) calculating the water percentage mass content Wpaper in the insulated paper by utilizing a formula (I), shown in the specification (I). The method of determining the water content in the insulated paper is capable of calculating the water content in the insulated paper by determining the temperature, the water content and the acid value of the insulating oil and then utilizing the formula (I), so that the steps are greatly reduced, the operation is simple, the consumed time is little, and measurement is accurate.

Description

In application insulating oil, acid number and moisture measure the method for moisture in insulating paper

Technical field

The invention belongs to electricity device field, relate to a kind of assay method of moisture, be specifically related to a kind ofly apply acid number and moisture in insulating oil and measure the method for moisture in insulating paper.

Background technology

Oil-immersed power transformer is one of key equipment of electric system.Research shows, the transformer fault of the overwhelming majority is caused by interior Insulation Problems.Oil-paper combination insulation is as the major insulation system of inside transformer, and under being in the rugged surroundings such as high temperature, humidity, chemical corrosion and electromagnetic field for a long time, its insulating property can significantly reduce, thus cause mechanical life and the electrical endurance serious curtailment of transformer.Insulating oil in oil-paper combination insulation recovers its insulating property by oil strain, the measure such as to change oil, and insulating paper is not easily changed and aging be irreversible, therefore the degree of aging of insulating paper directly determines the serviceable life of transformer.Hydrolytic degradation is the principal mode that insulating paper is aging, and in insulating paper, moisture doubles, and its mechanical life reduces by half, and heat ageing speed also will be accelerated at double; In insulating paper, moisture is many and not obvious by the impact of oil strain, the measure such as to change oil, and its Testing index as insulating paper ageing state has higher reliability.

The parameter that current internationally recognized judgement insulating paper reaches end of life is insulation paper polymerization degree.Insulation paper polymerization degree is the degree of aging that truly can reflect insulating paper.DL/T 596-2005 " power equipment preventive trial code " recommend the degree of polymerization lower than 250 time, should arouse attention.But the test of the degree of polymerization need be drained the oil to transformer and be hung cover, not only implement difficulty large, also may cause the damage of insulation.For the oil-filled transformer put into operation, owing to being difficult to directly to obtain insulating paper sample, when testing liquid water content in insulating paper, generally first adopt Karl_Fischer method, namely the moisture in KFT (Karl Fischer Titration) method test insulating oil, then the moisture in insulating paper is obtained according to the Oil-Paper Insulation moisture distribution profile of equilibrium; The paper oil insulation moisture distribution profile of equilibrium mainly Oommen curve of current use.Use Oommen curve to need moisture to reach equilibrium state at insulating oil and insulating paper, length consuming time, and trivial operations, therefore use the method test easy not and accurate.And insulating paper is aging can produce the organic acid such as formic acid, naphthenic acid, organic acid can affect the CONCENTRATION DISTRIBUTION of moisture between insulating oil and insulating paper, point out that in insulating oil, acid number may be used for characterizing paper oil insulation degree of aging simultaneously, therefore for running the longer transformer of the time limit, the degree of aging of its insulating paper is comparatively dark, adopts moisture in Oommen curve determination insulating paper can bring comparatively big error.

Summary of the invention

The present invention seeks to provide a kind of and apply acid number and moisture in insulating oil in order to overcome the deficiencies in the prior art and measure the method for moisture in insulating paper.

For achieving the above object, the technical solution adopted in the present invention is: a kind ofly apply acid number and moisture in insulating oil and measure the method for moisture in insulating paper, and it comprises the following steps successively:

A () gets the insulating oil of oil-immersed power transformer in work, the temperature T of the real time measure insulating oil;

B insulating oil that () gets part mensuration excess temperature is placed in karl Fischer titrator, measures the content W of wherein moisture _oil;

C insulating oil that () gets part mensuration excess temperature is again placed in automatic acid value tester, measures its acid number A _c;

D () utilizes formula (1) can calculate the mass percentage W of moisture in insulating paper _paper,

$W_{\mathrm{paper}}=16.59e^{-0.0423\×T}{[{10}^{7.8825\frac{2191.8}{273.15+T}}\×\frac{W_{\mathrm{oil}}}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^{0.0058\×T+0.3478}---\left(1\right).$

Optimally, described temperature T is 10 DEG C ~ 100 DEG C.

Optimally, step (b) is with in step (c), and the amount of taking of described insulating oil is 1 ~ 10 milliliter.

Because technique scheme is used, the present invention compared with prior art has following advantages: in the present invention's application insulating oil, acid number and moisture measure the method for moisture in insulating paper, it is only by measuring the temperature of insulating oil, moisture and acid number, then utilize formula (1) that moisture in insulating paper can be calculated, not only step significantly reduces, and simple to operate, institute takes time seldom, measure accurately.

figure of description

Fig. 1 is experimental facilities arrangenent diagram of the present invention;

Wherein, 1 is glassware, and 2 is aqueous glycerol solution, and 3 is perforated baffle, and 4 is open glass bottle, 5 is insulating paper, and 6 is insulating oil, and 7 is constant temperature oven, and 8 is Temperature Humidity Sensor, and 9 is humiture registering instrument, 10 is 1# sample, and 11 is 2# sample, and 12 is 3# sample, and 13 is 4# sample.

Embodiment

In the present invention's application insulating oil, acid number and moisture measure the method for moisture in insulating paper, and it comprises the following steps successively: (a) gets the insulating oil of oil-immersed power transformer in work, the temperature T of the real time measure insulating oil; B insulating oil that () gets part mensuration excess temperature is placed in karl Fischer titrator, measures the content W of wherein moisture _oil; C insulating oil that () gets part mensuration excess temperature is again placed in automatic acid value tester, measures its acid number A _c; D () utilizes formula (1) can calculate the mass percentage W of moisture in insulating paper _paper, $W_{\mathrm{paper}}=16.59e^{-0.0423\×T}{[{10}^{7.8825\frac{2191.8}{273.15+T}}\×\frac{W_{\mathrm{oil}}}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^{0.0058\×T+0.3478}---\left(1\right).$ It should be noted that temperature T to be determined is preferably 10 DEG C ~ 100 DEG C; Step (b) is with in step (c), and the amount of taking of insulating oil is preferably 1 ~ 10 milliliter, and the data measured like this are more accurate.

The principle that said determination method relates to is as follows: in aging insulating oil, in water saturation solubleness and insulating oil temperature, insulating oil, the relation of acid number meets Arrhenius equation, can be expressed as:

$W_s={10}^{A-\frac{B}{273.15+T}+m\×A_c}---\left(2\right);$

In formula, W _sbe water saturation solubleness in insulating oil, unit is ppm; T is the temperature of insulating oil, and unit is DEG C; A and B is correlation coefficient, relevant with the constituent, chemical property etc. of insulating oil; M is the shift factor relevant to acid number in insulating oil.

According to the uncommon adsorption isotherm (Freundlich Isotherm Equation) of Freund profit, the moisture be adsorbed in paper oil insulation system in insulating paper can be expressed as:

W _paper＝cP ⁿ(3)；

In formula, W _paperbe the content of moisture in insulating paper, represent by mass percentage or mass percent (%); C is adsorption equilibrium costant, generally reduces with the rising of temperature; N is the parameter of exosyndrome material absorption property power; P is by absorbed component (water vapour) equilibrium partial pressure in the gas phase, and unit is kPa.

Again due to the relative humidity (RH in air _air) refer to identical temperature under, water vapor in air pressure (P) and saturated vapor pressure (P _s) number percent, as shown in Equation 4:

${\mathrm{RH}}_{\mathrm{air}}=\frac{P}{P_s}\×100\%---\left(4\right);$

Relative humidity (RH in insulating oil _oil) refer to identical temperature under, moisture (W in insulating oil _oil) and water saturation solubleness (W _s) number percent, shown in (5):

${\mathrm{RH}}_{\mathrm{oil}}=\frac{W_{\mathrm{oil}}}{W_s}\×100\%---\left(5\right);$

In same environmental system, the relative humidity in different states of matter is equal, the relative humidity (RH therefore in air _air) with insulating oil in relative humidity (RH _oil) be equal, i.e. RH _air=RH _oil, then formula (4) and (5) simultaneous obtain formula (6):

$P=P_s\·\frac{W_{\mathrm{oil}}}{W_s}---\left(6\right).$

Wherein, the saturated vapor pressure numerical tabular under different temperatures is as shown in table 1, utilizes the data in this table matching can obtain under different temperatures saturated vapor pressure formula, shown in (7):

$P_s={10}^{7.8825-\frac{2191.8}{273.15+T}}---\left(7\right).$

Saturated vapor pressure numerical tabular under table 1 different temperatures

Temperature (DEG C)	10	15	20	25	30	35	40
								Saturated water vapor pressure (kPa)	1.2262	1.7068	2.3346	3.1684	4.2474	5.6207	7.3766
Temperature (DEG C)	45	50	55	60	65	70	75
								Saturated water vapor pressure (kPa)	9.5837	12.340	15.743	19.923	25.014	31.164	38.554
Temperature (DEG C)	80	85	90	95	100
								Saturated water vapor pressure (kPa)	47.379	57.875	70.136	84.556	101.33

In order to obtain parameter A, B, c and n, the present invention utilizes testing equipment as shown in Figure 1 to test, and is specially:

(1) insulating oil 6 (in insulating oil, moisture is lower than 10ppm) of drying and insulating paper 5 (in insulating paper, moisture is lower than 0.4%) are placed in open glass bottle 4 according to the ratio mixing that mass ratio is 18:1, make 4 parts of identical samples, numbering is respectively 1# sample 10,2# sample 11,3# sample 12,4# sample 13; Then by open glass bottle 4, be placed in normal temperature environment and leave standstill 72h, adopt the acid number in JKCS-3 automatic acid value tester test 1# sample 10 insulating oil;

(2) 2# sample 11,3# sample 12 and 4# sample 13 are all placed in constant temperature oven 7 and carry out acceleration heat ageing; Temperature in constant temperature oven 7 is set as 150 DEG C, and temperature fluctuation amplitude is ± 0.5 DEG C; Within 15 days, take out 2# sample 11 afterwards, adopt the acid number in JKCS-3 automatic acid value tester test insulating oil; Within 30 days, take out 3# sample 12 afterwards, adopt the acid number in JKCS-3 automatic acid value tester test insulating oil; Within 45 days, take out 4# sample 13 afterwards, adopt the acid number in JKCS-3 automatic acid value tester test insulating oil;

(3) aqueous glycerol solution 2 is placed in glassware 1, perforated baffle 3 is placed in above glassware 1, then glassware 1 is placed in constant temperature oven 7 together with perforated baffle 3, by open glass bottle 4 blow-by of 1# sample 10,2# sample 11,3# sample 12 and 4# sample 13, be then placed in above perforated baffle 3;

(4) by being placed in temperature and the relative humidity of the humiture registering instrument 9 Real-Time Monitoring constant temperature oven 7 outside the Temperature Humidity Sensor 8 of constant temperature oven 7 and constant temperature oven 7: first the temperature of regulating constant incubator 7 is 10 DEG C, according to the relative humidity in ASTM D5032-2011 working specification regulating constant incubator 7, until moisture after insulating oil 6 and insulating paper 5 reach equilibrium state, employing corneometer (915KF Ti-Touch body formula karl Fischer titrator) sporadically measures the moisture in insulating oil 6 and insulating paper 5; Then the temperature successively in regulating constant incubator 7 is 20 DEG C ~ 100 DEG C (10 DEG C, intervals), until moisture after insulating oil 6 and insulating paper 5 reach equilibrium state, sporadically measures the moisture in insulating oil 6 and insulating paper 5.

(5) insulating oil 6 of 4 parts of samples and insulating paper 5 are carried out respectively drying process, make in insulating oil 6 that moisture is lower than 10ppm, in insulating paper 5, moisture is lower than 0.4%, and the temperature in regulating constant incubator 7 is 10 DEG C, and relative humidity is 80%; When to show relative humidity be a constant numerical value to the humiture registering instrument 9 outside constant temperature oven 7, think that the moisture in insulating oil 6 reaches capacity, employing corneometer (915KF Ti-Touch body formula karl Fischer titrator) measures the moisture in insulating oil 6, and this value is water saturation solubleness in insulating oil; Water saturation solubleness in insulating oil 6 when the temperature of then testing respectively in constant temperature oven 7 according to the method is 15 DEG C ~ 100 DEG C (5 DEG C, interval).

By above test method, water saturation solubleness in 4 parts of samples insulating oil at different temperatures can be obtained, as shown in table 2.

Water saturation solubleness in insulating oil under table 2 different temperatures

Utilize the data in least square method his-and-hers watches 2 to carry out matching according to formula (2), parameter A, parameter B and parameter m can be obtained, wherein, A=7.26, B=1618.3, m=0.9384; So formula (2) is:

$W_s=10^{7.26-\frac{1618.3}{279.15+T}+0.9384\×A_c}---\left(2\right);$

By above test method, 4 parts of samples can be obtained under condition of different temperatures, when moisture is in equilibrium state between insulating paper and insulating oil, the moisture in insulating paper and insulating oil, as shown in table 3.

Moisture under table 3 different temperatures in insulating paper and insulating oil

Formula (6), formula (7) and formula (2) are substituted in formula (3), formula (8) can be obtained:

$W_{\mathrm{paper}}=c{[{10}^{7.8825-\frac{2191.8}{273.15+T}}\×\frac{W_{\mathrm{oil}}}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^n---\left(8\right);$

Data in recycling least square method his-and-hers watches 3 carry out matching according to formula (8), can obtain the parameter c under various sample and parameter n, then average, and can obtain the value of parameter c and parameter n under different temperatures, respectively as shown in table 4 and table 5.

The value of parameter c under table 4 different temperatures

The value of parameter n under table 5 different temperatures

Matching the relation of parameter c and temperature T can be obtained, shown in (9): c=16.59e according to the data in table 4 ^{-0.0423 × T}(9); Matching the relation of parameter n and temperature T can be obtained, shown in (10): n=0.0058 × T+0.3478 (10) according to the data in table 5; Formula (9) and formula (10) are substituted into formula (8), obtains moisture (W in insulating oil temperature (T, unit is: DEG C), insulating oil _oil, unit is: ppm) and insulating oil in the computing formula of moisture in the aging insulating paper of oil-filled transformer in acid number (Ac, unit is: mgKOH/g) situation, such as formula (1):

$W_{\mathrm{paper}}=16.59e^{-0.0423\×T}{[{10}^{7.8825\frac{2191.8}{273.15+T}}\×\frac{W_{\mathrm{oil}}}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^{0.0058\×T+0.3478}---\left(1\right).$

To be described in detail to the preferred embodiment of the invention below.

Embodiment 1

Get the insulating oil of oil-immersed power transformer in work, the temperature T of the real time measure insulating oil is 70 DEG C; Get the insulating oil that part (5ml) measures excess temperature and be placed in 915KF Ti-Touch body formula karl Fischer titrator, measure the content W of wherein moisture _oilfor 38.6ppm; Get the insulating oil that part (5ml) measures excess temperature again and be placed in JKCS-3 automatic acid value tester, measure its acid number A _cfor 0.068mgKOH/g.T=70 DEG C, W _oil=38.6ppm and A _c=0.068mgKOH/g substitutes in following formula, tries to achieve moisture in insulating paper:

$W_{\mathrm{paper}}=16.59e^{-0.0423\×T}{[{10}^{7.8825\frac{2191.8}{273.15+T}}\×\frac{W_{\mathrm{oil}}}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^{0.0058\×T+0.3478}(\%)$

That is:

$W_{\mathrm{paper}}=16.59e^{-0.0423\×T}{[{10}^{7.8825\frac{219.8}{273.15+T}}\×\frac{38.6}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^{00058\×70+0.3478}=1.995(\%)$

Therefore to test the moisture obtained in this oil-filled transformer insulating paper be 1.955%.

Embodiment 2

The insulating oil temperature T testing certain oil-filled transformer is 82 DEG C, and this temperature, between 10 DEG C ~ 100 DEG C, then adopts corneometer (915KF Ti-Touch body formula karl Fischer titrator) to measure moisture W in insulating oil _oilfor 42.8ppm, JKCS-3 automatic acid value tester is adopted to measure acid number A in insulating oil _cfor 0.105mgKOH/g.T=82 DEG C, W _oil=42.8ppm and A _c=0.105mgKOH/g substitutes in following formula, tries to achieve moisture in insulating paper:

$W_{\mathrm{paper}}=16.59e^{-0.0423\×T}{[{10}^{7.8825\frac{2191.8}{273.15+T}}\×\frac{W_{\mathrm{oil}}}{{10}^{7.26-\frac{1618.3}{273.15+T}+0.9384\×A_c}}]}^{0.0058\×T+0.3478}(\%)$

That is:

$W_{\mathrm{paper}}=16.59e^{-0.0423\×82}{[{10}^{7.8825\frac{2191.8}{273.15+82}}\×\frac{42.8}{{10}^{7.26-\frac{1618.3}{273.15+82}+0.9384\×0.105}}]}^{0.0058\×82+0.3478}=1.441(\%)$

Therefore to test the moisture obtained in this oil-filled transformer insulating paper be 1.441%.

Above-described embodiment, only for technical conceive of the present invention and feature are described, its object is to person skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.All equivalences done according to Spirit Essence of the present invention change or modify, and all should be encompassed within protection scope of the present invention.

Claims (3)

1. apply acid number and moisture in insulating oil and measure a method for moisture in insulating paper, it is characterized in that, it comprises the following steps successively:

A () gets the insulating oil of oil-immersed power transformer in work, the temperature T of the real time measure insulating oil;

B insulating oil that () gets part mensuration excess temperature is placed in karl Fischer titrator, measures the content W of wherein moisture _oil;

C insulating oil that () gets part mensuration excess temperature is again placed in automatic acid value tester, measures its acid number A _c;

D () utilizes formula (1) can calculate the mass percentage W of moisture in insulating paper _paper,

（1）。

2. the assay method of moisture in insulating paper according to claim 1, is characterized in that: described temperature T is 10 DEG C ~ 100 DEG C.

3. the assay method of moisture in insulating paper according to claim 1, is characterized in that: in step (b) and step (c), the amount of taking of described insulating oil is 1 ~ 10 milliliter.