CN105092660A - Transformer winding material identification method based on resistance temperature coefficient - Google Patents

Abstract

A transformer winding material identification method based on a resistance temperature coefficient comprises the steps: firstly, placing a to-be-detected transformer in a 20-100 DEG C high-temperature test box, arranging four temperature measuring points respectively being a top oil temperature point, a winding connector point, a front side bottom point and a back top point at the periphery of the transformer, and determining the temperature of a transformer winding through measuring the temperatures of the four points; then changing the temperature of the high-temperature test box, and after the transformer temperature is completely stable, namely the temperatures of the four temperature measuring points are the same and consistent with the set temperature of the test box, measuring the direct-current resistance of the transformer winding through a transformer direct-current resistance tester; and then carrying out data analysis on the measured direct-current resistance values of the transformer winding at different temperatures. Through measuring the direct-current resistance values of the transformer winding at the different temperatures, the material of the winding is identified from the change condition of the resistance values. The measuring principle is simple, judgment accuracy is high, and no hang cover is needed so as to avoid destroying of insulation of the winding.

Description

A kind of Transformer Winding material discrimination method based on temperature-coefficient of electrical resistance

Technical field

The invention belongs to Transformer Winding material discrimination technical field.

Background technology

In the substation transformer of power transformer, especially 10kV rank, long-term existence the phenomenon using wire instead of copper wire.Particularly in recent years, because domestic and international copper valency remains high, the quantity of aluminium winding transformer presents the trend increased considerably.Existingly not yet restriction is made to the material of Transformer Winding, if but require to use aluminium winding clearly need identify in transformer model.The aluminium winding transformer overwhelming majority existed on the market at present then belongs to manufacturer and substitutes winding for another surreptitiously situation into aluminum steel by copper cash to save cost, and power consumer is ignorant when buying and run.

Due to the difference in copper aluminium material matter characteristic, aluminium winding transformer itself also exists the deficiency in performance.Transformer production number of the enterprise is huge simultaneously, and many small enterprises not possessing the necessary ability such as quality control and testing inspection unworthily occupy a place among them, and its aluminium winding transformer quality of producing is difficult to ensure especially.Show according to State Grid Corporation of China's transformer ' s type equipment breakdown statistical study: Transformer Winding is the primary damage position of transformer damage accident, exceed 70% of total damage accident, wherein winding Short Circuit withstand insufficient strength and insulation defectiveness are the main causes of damage accident.From crash analysis, the quality problems of Transformer Winding very easily cause security incident, use existing aluminium winding transformer will greatly to increase the risk of transformer damage, in whole Operation of Electric Systems, bury potential safety hazard.Therefore must strengthen the quality control of Transformer Winding, screen out shoddy aluminium winding transformer in electric system.

China's power transformer dispatches from the factory and has to pass through routine test, type approval test and special test, and wherein closely-related test comprises with Transformer Winding: winding resistance is measured, short-circuit test, no-load test, temperature rise test etc.These tests all can not be used for detecting aluminium winding transformer, research also not relevant both at home and abroad.

At present, equipment control department just can only can detect winding conductor type by destroying winding insulation after hanging cover.But the method wastes time and energy, accuracy is not high has nonreversibility simultaneously.

Summary of the invention

The object of the invention is to solve the deficiencies in the prior art, provide a kind of method of the discriminating Transformer Winding material that can effectively can't harm, to realize the discriminating of copper aluminium winding transformer quickly and easily.

Object of the present invention is achieved through the following technical solutions:

Based on a Transformer Winding material discrimination method for temperature-coefficient of electrical resistance, step is:

1) transformer to be measured is positioned in the high-temperature test chamber of 20-100 DEG C, arrange 4 points for measuring temperature around, be respectively: top-oil temperature point, winding joint point, front base point, top, back side point, judge the temperature of Transformer Winding by the temperature measuring these four points; Change the temperature of high-temperature test chamber, until the transformer temperature complete stability i.e. temperature of 4 points for measuring temperature identical and consistent with chamber design temperature time, by the direct current resistance of direct-current resistance tester for transformer measuring transformer winding;

2) data analysis is carried out to the Transformer Winding DC resistance measured under the different temperatures that obtains:

The variation relation of the electrical resistance temperature of copper and aluminium is respectively such as formula shown in (1) and (2):

R _t＝R ₀(1+4.666×10 ^-3t)(2)

In formula: Rt is the resistance value of metal material when t DEG C; Resistance value when R0 is 0 DEG C; T is Celsius temperature;

Obtain the resistance temperature phasing meter of copper and aluminium respectively according to formula (1) and formula (2), the mean value getting copper and aluminium resistance temperature calibration tabular value forms form as the reference value based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method;

Transformer Winding DC resistance data analysis under the different temperatures that test is recorded; If test record Transformer Winding t1 DEG C, t2 DEG C time DC resistance be respectively R1, R2, value when obtaining 2 corresponding temperature points t1 DEG C, t2 DEG C by the reference value form looked into based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method is respectively k1, k2; If R2/R1 is greater than k2/k1, then judge that winding material is as aluminium, if R2/R1 is less than k2/k1, then judge that winding material is as copper.

The present invention is copper or aluminium to effectively screen Transformer Winding material, proposes the Transformer Winding material discrimination method based on temperature-coefficient of electrical resistance.By DC resistance during measuring transformer winding different temperatures, differentiate winding material by the situation of change of resistance value.Measuring principle is simple, and accuracy of judgement degree is high, and destroying winding insulation without the need to hanging cover, is a kind of lossless detection method.

Accompanying drawing explanation

Fig. 1 is the Transformer Winding material discrimination method schematic diagram based on temperature-coefficient of electrical resistance;

Fig. 2 shows the linear function of copper and the relative error of cubic function resistance temperature relational expression;

Fig. 3 is the relation curve of copper and aluminium electrical resistance temperature;

Embodiment

As shown in Figure 1, a kind of Transformer Winding material discrimination method based on temperature-coefficient of electrical resistance, step is:

1) transformer to be measured is positioned in high-temperature test chamber (20-100 DEG C), arrange 4 points for measuring temperature around, be respectively: top-oil temperature point, winding joint point, front base point, top, back side point, judge the temperature of Transformer Winding by the temperature measuring these four points; Change the temperature of high-temperature test chamber, until the transformer temperature complete stability i.e. temperature of 4 points for measuring temperature identical and consistent with chamber design temperature time, by the direct current resistance of direct-current resistance tester for transformer measuring transformer winding;

2) data analysis is carried out to the Transformer Winding DC resistance measured under the different temperatures that obtains:

The variation relation of the electrical resistance temperature of copper and aluminium is respectively such as formula shown in (1) and (2):

R _t＝R ₀(1+4.666×10 ^-3t)(2)

In formula: Rt is the resistance value of metal material when t DEG C; Resistance value when R0 is 0 DEG C; T is Celsius temperature;

The resistance temperature phasing meter of copper and aluminium is obtained respectively, in table 1, table 2 according to formula (1) and formula (2).The mean value getting copper and aluminium resistance temperature calibration tabular value forms form, in table 3 as the reference value based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method.

Table 1 copper resistance temperature phasing meter

℃	0	1	2	3	4	5	6	7	8	9
											0	1.0000	1.0043	1.0086	1.0129	1.0172	1.0214	1.0257	1.0300	1.0343	1.0386
10	1.0429	1.0472	1.0514	1.0557	1.0600	1.0643	1.0686	1.0729	1.0771	1.0814
											20	1.0857	1.0900	1.0943	1.0986	1.1028	1.1071	1.1114	1.1157	1.1200	1.1242
30	1.1285	1.1328	1.1371	1.1414	1.1456	1.1499	1.1542	1.1585	1.1627	1.1670
											40	1.1713	1.1756	1.1799	1.1841	1.1884	1.1927	1.1970	1.2012	1.2055	1.2098
50	1.2141	1.2184	1.2226	1.2269	1.2312	1.2355	1.2397	1.2440	1.2483	1.2526
											60	1.2568	1.2611	1.2654	1.2697	1.2740	1.2782	1.2825	1.2868	1.2911	1.2953
70	1.2996	1.3039	1.3082	1.3124	1.3167	1.3210	1.3253	1.3296	1.3338	1.3381
											80	1.3424	1.3467	1.3509	1.3552	1.3595	1.3638	1.3681	1.3723	1.3766	1.3809
90	1.3852	1.3895	1.3937	1.3980	1.4023	1.4066	1.4109	1.4152	1.4194	1.4237

Table 2 aluminium resistance temperature phasing meter

℃	0	1	2	3	4	5	6	7	8	9
											0	1.0000	1.0047	1.0093	1.0140	1.0187	1.0233	1.0280	1.0327	1.0373	1.0420
10	1.0467	1.0513	1.0560	1.0607	1.0653	1.0700	1.0747	1.0793	1.0840	1.0887
											20	1.0933	1.0980	1.1027	1.1073	1.1120	1.1167	1.1213	1.1260	1.1307	1.1353
30	1.1400	1.1446	1.1493	1.1540	1.1586	1.1633	1.1680	1.1726	1.1773	1.1820
											40	1.1866	1.1913	1.1960	1.2006	1.2053	1.2100	1.2146	1.2193	1.2240	1.2286
50	1.2333	1.2380	1.2426	1.2473	1.2520	1.2566	1.2613	1.2660	1.2706	1.2753
											60	1.2800	1.2846	1.2893	1.2940	1.2986	1.3033	1.3080	1.3126	1.3173	1.3220
70	1.3266	1.3313	1.3360	1.3406	1.3453	1.3500	1.3546	1.3593	1.3640	1.3686
											80	1.3733	1.3780	1.3826	1.3873	1.3920	1.3966	1.4013	1.4059	1.4106	1.4153
90	1.4199	1.4246	1.4293	1.4339	1.4386	1.4433	1.4479	1.4526	1.4573	1.4619

Table 3 is based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method reference value

℃	0	1	2	3	4	5	6	7	8	9
											0	1.0000	1.0045	1.0090	1.0134	1.0179	1.0224	1.0269	1.0313	1.0358	1.0403
10	1.0448	1.0492	1.0537	1.0582	1.0627	1.0671	1.0716	1.0761	1.0806	1.0850
											20	1.0895	1.0940	1.0985	1.1029	1.1074	1.1119	1.1164	1.1208	1.1253	1.1298
30	1.1343	1.1387	1.1432	1.1477	1.1521	1.1566	1.1611	1.1656	1.1700	1.1745
											40	1.1790	1.1834	1.1879	1.1924	1.1969	1.2013	1.2058	1.2103	1.2147	1.2192

50	1.2237	1.2282	1.2326	1.2371	1.2416	1.2460	1.2505	1.2550	1.2595	1.2639
											60	1.2684	1.2729	1.2773	1.2818	1.2863	1.2908	1.2952	1.2997	1.3042	1.3086
70	1.3131	1.3176	1.3221	1.3265	1.3310	1.3355	1.3400	1.3444	1.3489	1.3534
											80	1.3578	1.3623	1.3668	1.3713	1.3757	1.3802	1.3847	1.3891	1.3936	1.3981
90	1.4026	1.4070	1.4115	1.4160	1.4205	1.4249	1.4294	1.4339	1.4384	1.4428

Transformer Winding DC resistance data analysis under the different temperatures that test is recorded; If test record Transformer Winding t1 DEG C, t2 DEG C time DC resistance be respectively R1, R2, value when obtaining 2 corresponding temperature points t1 DEG C, t2 DEG C by the reference value form looked into based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method is respectively k1, k2; If R2/R1 is greater than k2/k1, then judge that winding material is as aluminium, if R2/R1 is less than k2/k1, then judge that winding material is as copper.

The principle of the inventive method is as follows:

Owing to there is linear relationship approx between the resistivity of metal and temperature, then the resistance value of metal and the relation of temperature are also approximately linear:

R _t＝R ₀(1+αt)(3)

In formula: Rt is the resistance value of metal material when t DEG C; Resistance value when R0 is 0 DEG C; α is the temperature-coefficient of electrical resistance of metal.

During accurate Calculation, there is following relation in metallic resistance and temperature:

R _t＝R ₀(1+αt+βt ²+γt ³+……)(4)

In formula: α, β, γ are respectively temperature-coefficient of electrical resistance, secondary temperature-coefficient of electrical resistance, three temperature-coefficient of electrical resistances.

When temperature is different, the temperature-coefficient of electrical resistance of metal is different.The temperature-coefficient of electrical resistance of copper aluminium 20 DEG C time is respectively 0.00393,0.00429, the temperature-coefficient of electrical resistance correction coefficient Kt that temperature-coefficient of electrical resistance during all the other temperature can be provided by GB " GB3956-1983 electrical equipment electric wire copper, aluminium conductor wire core " revises:

$K_{t-Cu}=\frac{1}{1+0.00393(t-20)}---\left(5\right)$

$K_{t-Al}=\frac{1}{1+0.00403(t-20)}---\left(6\right)$

Can be calculated copper and the correction coefficient of aluminium 0 DEG C time is respectively 1.0853,1.0877, obtain copper thus and the temperature-coefficient of electrical resistance of aluminium 0 DEG C time is respectively 0.00393 × 1.0853=0.004265,0.004666.Then the linear function resistance temperature relational expression of copper and aluminium is:

R _t＝R ₀(1+4.265×10 ^-3t)(7)

R _t＝R ₀(1+4.666×10 ^-3t)(8)

The cubic function resistance temperature relational expression that " JB/T8623-1997 standard copper thermal resistance technical conditions and phasing meter " gives copper is:

R _t＝R ₀[1+4.280×10 ^-3t-9.31×10 ^-8t(t-100)+1.23×10 ^-9t ²(t-100)](9)

Existing document does not provide the more accurate resistance temperature relational expression of aluminium, therefore first variance analysis is carried out to the linear function resistance temperature relational expression of copper, cubic function resistance temperature relational expression, the relative error of the linear function of copper and cubic function resistance temperature relational expression can be obtained as shown in Figure 2 by formula (7) and formula (9).Can see that the linear function of copper and cubic function resistance temperature relational expression are only 0.1% from the maximum relative error of 0 DEG C to 100 DEG C, illustrate that the accuracy of linear function resistance temperature relational expression is higher.Therefore the resistance temperature relation of aluminium can be represented by formula (8), obtains the resistance temperature relation curve of copper and aluminium thus as shown in Figure 3.

Such as, test with two S11-M-50/10 copper aluminium winding substation transformers.Because transformer is heated very slow, test have selected three temperature spots altogether: 35 DEG C, 55 DEG C, 75 DEG C, copper aluminium winding transformer DC resistance when table 4 is different temperatures.

Table 4 temperature-coefficient of electrical resistance method instance data

Get 75 DEG C and 35 DEG C of resistance values are verified.Copper aluminium winding transformer 75 DEG C is respectively 33.12/29.02=1.1413,42.10/36.35=1.1582 with the ratio of 35 DEG C of resistance values.It is that 1.3355/1.1566=1.1547. can see that the ratio of copper winding transformer two temperatures resistance value is less than reference value that look-up table 3 obtains 75 DEG C with the reference value of 35 DEG C of resistance value ratios, and the ratio of aluminium winding transformer two temperatures resistance value is greater than reference value.Demonstrate accuracy and the validity of the method.Get 55 DEG C and 35 DEG C of data, 75 DEG C can be calculated same conclusions with 55 DEG C of data.

Claims (1)

1., based on a Transformer Winding material discrimination method for temperature-coefficient of electrical resistance, it is characterized in that, step is:

1) transformer to be measured is positioned in the high-temperature test chamber of 20-100 DEG C, arrange 4 points for measuring temperature around, be respectively: top-oil temperature point, winding joint point, front base point, top, back side point, judge the temperature of Transformer Winding by the temperature measuring these four points; Change the temperature of high-temperature test chamber, until the transformer temperature complete stability i.e. temperature of 4 points for measuring temperature identical and consistent with chamber design temperature time, by the direct current resistance of direct-current resistance tester for transformer measuring transformer winding;

2) data analysis is carried out to the Transformer Winding DC resistance measured under the different temperatures that obtains:

The variation relation of the electrical resistance temperature of copper and aluminium is respectively such as formula shown in (1) and (2):

R _t＝R ₀(1+4.666×10 ^-3t)（2）

In formula: Rt is the resistance value of metal material when t DEG C; Resistance value when R0 is 0 DEG C; T is Celsius temperature;

Obtain the resistance temperature phasing meter of copper and aluminium respectively according to formula (1) and formula (2), the mean value getting copper and aluminium resistance temperature calibration tabular value forms form as the reference value based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method;

Transformer Winding DC resistance data analysis under the different temperatures that test is recorded; If test record Transformer Winding t1 DEG C, t2 DEG C time DC resistance be respectively R1, R2, value when obtaining 2 corresponding temperature points t1 DEG C, t2 DEG C by the reference value form looked into based on temperature-coefficient of electrical resistance Transformer Winding material discrimination method is respectively k1, k2; If R2/R1 is greater than k2/k1, then judge that winding material is as aluminium, if R2/R1 is less than k2/k1, then judge that winding material is as copper.