JPH0373875A - Method for deciding deterioration of insulation in coil of rotating machine - Google Patents

Abstract

PURPOSE:To accurately decide deterioration by checking whether a coil insulating layer based upon a resin insulating system is in a dry state or a hygroscopic state and specifying the inspection items of respective states. CONSTITUTION:In order to decide the deteriorated state of the insulating layer of the coil, whether the insulating layer is dry or hygroscopic is checked. At the time of the dry state, the insulation deteriorating state is decided based upon the following inspection items and the deteriorated state in the hygroscopic state is similarly decided based upon the following inspection items. Namely, the inspection items in the dry state are the ratio VBD/Pi2 of a dielectric breakdown voltage VBD to a 2nd current sudden increment point Pi2, a current increment rate I, partial discharge generation frequency (n), partial discharge starting voltage Vi, maximum discharging charge Qmax, and the product R.C. of an insulation resistance value R and electrostatic capacity C. On the other hand, the inspection items in the hygroscop ic state are insulation resistance R, the resistance ratio log (DDry/Dwet) of the resistance RDry of the steady state to the resistance Twet of the hygroscopic state, dielectric loss tangent tandelta0, electrostatic capacity C0, the product R.C of the insulation resistance R and electrostatic capacity C, the frequency characteristic of electrostatic capacity to be the ratio of electrostatic capacity values in two different frequency bands, and the ratio C(hygroscopic)/C(dry) of the electrostatic capacity C in the hygroscopic state to the electrostatic capacity C in the dry state.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining insulation deterioration of a rotating machine coil, and is a method for determining insulation deterioration of a coil insulated by a resin insulation method.

B9 Summary of the Invention The present invention examines whether a coil insulating layer insulated using a resin insulation method is dry or absorbs moisture, specifies inspection items when dry and inspection items when moisture is absorbed, and insulates the coil. This is a method for determining insulation deterioration.

C0 Conventional Technology The insulation method for high-voltage rotating machine coils was introduced in the first half of the 1950s, and resin insulation methods using synthetic resin have been adopted instead of compound insulation methods. In the compound insulation method, after wrapping mica tape around the conductor, asphalt compound is press-fitted at high temperature to provide insulation. On the other hand, in the resin insulation method, after winding mica tape around a conductor, the conductor is vacuum impregnated with a solvent-free resin and then heated and cured to provide insulation. The resin insulation method has superior heat resistance and electrical performance compared to the compound insulation method, so since adopting the resin insulation method, the operating temperature of equipment and the strength of the electric field used have significantly improved. I've been doing it.

On the other hand, especially in recent years, the thickness of the insulating layer has been reduced as devices have become smaller and lighter, and as devices have become more sophisticated, the stresses such as voltage, heat, and mechanical force applied to the insulating layer have become stronger. As a result, although damage caused by insulation deterioration was small when the resin insulation method was first adopted for high-voltage rotating machines, damage caused by insulation deterioration has actually become larger in recent years.

D. Problems to be Solved by the Invention As mentioned above, insulation deterioration damage has become a problem in recent years, but the insulation deterioration judgment standard, which involves knowing the degree of insulation deterioration and determining the deterioration based on that, has not been used in the past. Although a unified standard proposed by the Central Research Institute of Electric Power Industry has been established for the foam pound insulation method, there are currently no valid standards for the resin insulation method, which is currently the mainstream.

In view of the above circumstances, the present invention provides a method for determining insulation deterioration of a rotating machine coil, which allows knowing the degree of insulation deterioration of a high-voltage rotating machine coil using a resin insulation method and accurately determining the deterioration. be.

80 Means for Solving the Problems The present invention solves the above problems by checking whether the insulation layer of a rotating machine coil insulated using a resin insulation method is dry or absorbing moisture, and when dry, ( 1) Second current rapid increase point P12 and dielectric breakdown voltage V.

The ratio with V,. /P, 2, (2) Current increase rate Δ11 (3) Partial discharge occurrence frequency n1 (4) Partial discharge starting voltage vl, (5) Maximum discharge charge Qllllll)l, (6) Insulation resistance value R and capacitance The product of C is R-C.

Insulation deterioration is determined based on, and when moisture is absorbed, (7) Insulation resistance R1 (8) Resistance ratio between resistance R0, during normal state and resistance tag when moisture is absorbed, log (RO,, / R, □), (9) Dielectric loss tangent δ. , 01 Capacitance C0, (11J Product R-C of insulation resistance R and capacitance C.

(1. Frequency characteristics of capacitance, which is the ratio of capacitance at two different frequencies. C' (moisture absorption) / C' (drying)
It is characterized by determining the insulation deterioration of the insulating layer based on , .

F. Example In the method of the present invention, to determine the deterioration state of the insulating layer of the coil, first check whether the insulating layer is dry or absorbs moisture, and when dry, perform the following (1) to (6). The state of insulation deterioration is determined based on the inspection items (7) to (11) shown below at the time of moisture absorption.

For 11 [KV] class coils, if the value shown in the parentheses of the inspection item is reached, it is determined that the coil is in a dangerous area where deterioration has progressed. In this determination, even if the value of one of the inspection items becomes dangerous, even if the values of the other items are in the safe range, the deterioration has progressed and it is determined to be dangerous.

(1) Second current rapid increase point P12 and dielectric breakdown voltage V.

Donobi V. /P, (1,8~2.2) (2) Current increase rate ΔI (4.0% or more when 1,25E/l-, 8.0% or more when E) (3) Partial discharge Occurrence frequency n (4) Partial discharge starting voltage V (5) Maximum discharge charge Q.

(6) Product R-C of insulation resistance value R and capacitance C (600Ω
F or less) (7) Insulation resistance R (8) Resistance R0,,y during normal conditions and resistance tag during moisture absorption.

The resistance ratio log(R,,,/RL,1.) (3,
0 or more) (9) Dielectric loss tangent −δ. (8.0% or more) α groan
Capacitance C0 (2) Product of insulation resistance R and capacitance C RC (3ΩF or less) 04 Frequency characteristic of capacitance C12°H-/CL. , (1.5 or more) Ratio of capacitance C during moisture absorption (moisture absorption) to capacitance C during drying (dry) C (moisture absorption) /C (dry) (1.6 or more at 1kHz) The experiments that led to the above results will be described below.

First, the sample used in the experiment will be explained based on FIG. In the sample coil 1, mica tape (mixed flake mica tape and Ill mica tape) is wound around the conductor la, which is made by bundling a plurality of rod conductors with a length of 600 mm, to form an insulating layer 1b.
The insulating layer 1b is impregnated with resin (polyester resin) and cured by heating.

At the center of the coil 1, a low resistance layer 2 having a length of 160 layers was attached by winding it on the insulating layer lb, and the coil 1 was housed in the model slot 3. This model slot 3 is used as a low-voltage side electrode in experiments described later, and a high-overwhelm electrode is attached to the conductor 1a.

Coil 1, which is a sample, undergoes thermal deterioration in the furnace,
After that, it was placed in a cantilevered form with one end fixed and the other end subjected to vibration deterioration. Furthermore, moisture absorption was made to include environmental factors. These deterioration conditions are as follows.

Thermal deterioration conditions 160°C (MAX 100 days) Vibration deterioration conditions 1500μ5 train (large amount of strain) Moisture absorption conditions Relative humidity 95% or more (2 days) Using sample coil 1 degraded in this way, A DC voltage test, a dielectric loss tangent test, an AC current test, a partial discharge test, and other tests were conducted as described.

Here, the correlation between the test, inspection items, and residual dielectric strength (correlations are marked with O) is shown in a table. The values in the table are dangerous values for 11KV class coils.

Figure 2 shows the circuit for DC voltage testing. In this test, a DC voltage was applied to the sample coil 1, and the insulation resistance R of the insulating layer 1b was
is measured using a super megohmmeter 10. The measurement items are an insulation resistance value R1 for one minute after starting voltage application, and an insulation resistance value RIO for 100 minutes after starting voltage application. Further, the applied voltage was 100OV.

From this DC voltage test, the polarization index P, I is determined by the following formula % formula % At this time, if P, I ≧ 2.0, it is determined that it is dry, and if P, I < 2.0, it is determined that it is dry. It is determined that the

Figure 3 shows the resistance R8 under normal conditions, obtained by a DC voltage test.
y, the resistance Ru during moisture absorption, and which resistance ratio log (Ro□/R
1, l, , ) are shown. This experiment shows that insulation deterioration during moisture absorption can be determined based on the resistance ratio.

In other words, when the value of log (Ro, , / R, , ) exceeds a certain value, it becomes impossible to maintain the proof stress (2E+1) KV required for operation. Note that E is the rated voltage.

Insulation deterioration due to moisture absorption can also be determined by inspecting the insulation resistance R.

Figure 4 shows a circuit for conducting a dielectric loss tangent test and an alternating current test. In the dielectric loss tangent test, a commercial frequency voltage is applied to the sample coil 1, and the detection unit 11 detects the insulation [dielectric loss tangent of 1b - δ]. and detect capacitance C8. The detected data is displayed on a display section 13 connected via an optical fiber cable 12. In the alternating current test, a commercial frequency voltage is applied to the sample coil 1, and the detection unit 11 detects the second current rapid increase point P,2 and the dielectric breakdown voltage V,. Which ratio "ao/" +2, applied voltage is 1.2
The current increase rate Δ■1 when the applied voltage is 5E/43 and the current increase rate Δ■2 when the applied voltage is E are detected.

Figure 5 shows the dielectric loss tangent -δ during moisture absorption obtained from the dielectric loss tangent test.
. Experimental data is shown. From this experiment, the dielectric loss tangent −δ during moisture absorption. It can be seen that insulation deterioration can be determined based on this.

Insulation deterioration during moisture absorption can also be determined by inspecting the capacitance C0.

FIG. 6 shows the difference between the second current rapid increase point P1□ and the dielectric breakdown voltage v8° during drying obtained from an alternating current test. /P,
The experimental data of 2 is shown. This experiment shows that insulation deterioration can be determined based on the ratio '+50/Pl 2 when dry.

FIG. 7 shows experimental data of the current increase rate Δ11 (when the applied voltage is 1.25E/43) and the current increase rate ΔI2 (when the applied voltage is E) during drying obtained by an alternating current test. From this experiment, the current increase rate Δ during drying! 1
．． It can be seen that insulation deterioration can be determined based on ΔI2.

FIG. 8 shows a circuit for performing a partial discharge test.

In the partial discharge test, a commercial frequency voltage is applied to the sample coil 1, and the detection unit 14 and corona measuring device 15 measure the partial discharge occurrence frequency n, the partial discharge inception voltage (■), and the maximum discharge charge Q1.
8 is detected.

Figure 9 shows the o + f 6 during drying obtained from the partial discharge test.
．． 4 Experimental data on partial discharge occurrence frequency n of each coil of KV class, B KV class, and IIKV class is shown. This experiment shows that insulation deterioration can be determined based on the partial discharge occurrence frequency n during drying.

FIG. 10 shows experimental data of the partial discharge inception voltage V (at 32 PC and at 100 OPC) during drying obtained from a partial discharge test. This experiment shows that insulation deterioration can be determined based on the partial discharge inception voltage V during drying.

Figure 11 shows 6 during drying obtained from the partial discharge test.
Experimental data of maximum discharge charge Q9.8 of 4KV class and 8KV class coils is shown. This experiment shows that insulation deterioration can be determined based on the maximum discharge charge Q, 8 during drying.

Figure 12 shows the insulation resistance value R when dry (DC 1000
Experimental data of the product RC of the Meg value (Meg value when 1 minute has elapsed after applying V) and the capacitance C (value when IKHz is applied) are shown. This data shows that insulation deterioration can be determined from the RC value during drying.

Figure 13 shows the insulation resistance value R (DC 1000
Experimental data of the product RC of the Meg value (one minute after applying V) and the capacitance C (value at IKHz and 120 Hz) are shown. This data shows that insulation deterioration can be determined from the RC value during moisture absorption.

Figure 14 shows the capacitance C(
(value at 120Hz) and capacitance C8゜(IKHz
Frequency characteristic C82゜H□/C
Experimental data of IKH engineering is shown. This data shows that insulation deterioration can be determined based on the frequency characteristic C42°Ht/CIK+4x during moisture absorption.

FIG. 15 shows experimental data of the ratio C(moisture absorption)/C(dry) of the capacitance C during moisture absorption (moisture absorption) and the capacitance C during drying (dry). From this data, when moisture is absorbed, C (moisture absorption)
It can be seen that insulation deterioration can be determined from the value of /C (dry).

As described in detail of the G9 invention, according to the present invention, the deterioration state of the insulating layer of a coil insulated with resin can be accurately determined by testing specific items.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a sample coil, Fig. 2 is a circuit diagram showing a circuit showing a DC voltage test, Fig. 3 is a characteristic diagram showing experimental data of resistance ratio log (Ro, , / Ruet), Fig. 4 is a circuit diagram showing a circuit for conducting a dielectric loss tangent test and an alternating current test, and Fig. 5 shows a dielectric loss tangent -δ. Figure 6 is a characteristic diagram showing experimental data for ratio v6°/P, 2, Figure 7 is a characteristic diagram showing experimental data for current increase rate Δ■, Figure 8 is partial discharge. A circuit diagram showing the circuit to be tested. Fig. 9 is a characteristic diagram showing experimental data of partial discharge occurrence frequency n. Fig. 10 is a characteristic diagram showing experimental data of partial discharge inception voltage ■. Fig. 11 is a maximum discharge charge. Figures 12 and 13 are characteristic diagrams showing experimental data of product RC. Figure 14 is a characteristic diagram showing experimental data of frequency characteristics of capacitance. The figure is a characteristic diagram showing experimental data on the ratio of capacitance during moisture absorption and drying. In the drawing, 1 is a coil, 1a is a conductor, 1b is an insulating layer, 2 is a low resistance layer, 3 is a model slot, 10 is a super megohmmeter, 11.14 is a detection part, 12 is an optical fiber cable) 13 is a display part It is.

Claims (1)

[Claims] It is checked whether the insulating layer of the rotating machine coil, insulated by the resin insulation method, is dry or absorbs moisture. Voltage V_B
_D ratio V_B_D/P_i_2, (2) current increase rate ΔI, (3) partial discharge occurrence frequency n, (4) partial discharge starting voltage V_i, (5) maximum discharge charge Q_m_a_x, (6) insulation resistance value R. Insulation deterioration is determined based on the product R・C of capacitance C, and when moisture is absorbed, (7) insulation resistance R, (8) resistance during normal state R_D_r_y and resistance during moisture absorption R_
Resistance ratio log(R_D_r_y/R_W
_e_t), (9) dielectric loss tangent tanδ_o, (10) capacitance C_o, (11) product R・C of insulation resistance R and capacitance C, (12) ratio of capacitance at two different frequencies. Frequency characteristics of capacitance, (13) Ratio of capacitance C during moisture absorption (moisture absorption) to capacitance C during drying (dry), C (moisture absorption)/C (dry), of the insulating layer. A method for determining insulation deterioration of a rotating machine coil, the method comprising determining insulation deterioration.