JPH057662B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial and Field of Application) The present invention provides a method and apparatus for diagnosing the insulation state of high-voltage electrical equipment that serves as a drive source for the main blower of a blast furnace, as well as various mechanical equipment and electrical devices. In particular, the present invention relates to an insulation diagnostic method for electrical equipment and a diagnostic device for improving insulation diagnostics.

(Prior art) Generally, when high-voltage electrical equipment related to a production line stops functioning due to winding failure such as deterioration of insulation, the production line will be out of operation for a long period of time.
There is a risk of significant damage. Therefore, in the case of high-voltage electrical equipment with advanced insulation deterioration that is nearing the end of its lifespan, it is desirable to replace it with a new equipment as soon as possible, but replacing the equipment costs an enormous amount of money. Therefore, it is necessary to appropriately and accurately diagnose the degree of insulation deterioration and take optimal measures according to the degree of insulation deterioration, such as varnishing, rewinding, or replacing with a new one, to improve economic efficiency. I'm getting old.

Therefore, conventionally, several diagnostic methods have been adopted from this point of view, such as the DC test method, dielectric loss tangent test method, AC current test method, and corona test method. is being diagnosed.

The DC test method calculates the polarization index PI: {PI=
(Insulation resistance value 10 minutes after starting DC current) /
(Insulation resistance value 1 minute after the start of DC current flow)} is determined, and only moisture absorption deterioration is diagnosed based on this polarization index PI.If moisture absorption deterioration occurs, the polarization index
PI becomes smaller.

Next, the dielectric loss tangent test method diagnoses moisture absorption deterioration and void deterioration from the relationship between the applied AC voltage and dielectric loss tangent tan δ. When moisture absorption deterioration occurs, tan δ increases when voltage is applied, causing void deterioration. At a predetermined applied voltage, tan δ becomes small.

The AC test method diagnoses insulation from the relationship between the applied AC voltage and the magnitude of the detected current.When void deterioration occurs, the slope of the current increase curve changes due to corona discharge, causing a sudden increase. do.

The corona test method diagnoses the insulation property from the relationship between the applied AC voltage and the maximum discharge charge Qmax or the total charge Qo. When void deterioration occurs, the maximum discharge charge Qmax also becomes the total charge Qo. becomes larger.

(Problems to be Solved by the Invention) However, all of the above four test methods require large-scale measurement equipment, require a long time for measurement, and are extremely expensive. Furthermore, there were problems such as lack of simplicity as a measuring device and poor reliability of the diagnostic results.

The present invention has been made in view of the above circumstances, and it is possible to easily and highly accurately diagnose the degree of insulation deterioration of electrical equipment, and to avoid long-term suspension of production line operation due to malfunction of electrical equipment. An object of the present invention is to provide an insulation diagnosis method for electrical equipment and a diagnostic device thereof, which can improve economic efficiency through appropriate maintenance according to the degree of insulation deterioration.

(Means for Solving the Problems) The insulation diagnosis method for electrical equipment according to the present invention detects the leakage current of the electrical equipment with a sensor, and uses the output signal of this sensor to conduct a static test using an insulation constant calculation circuit having a high frequency bridge. After determining the capacitance and dielectric loss factor, obtain the capacitance increase rate, this capacitance increase rate, and the insulation deterioration constant obtained from the dielectric loss factor, and calculate these capacitance increase rate and The insulation deterioration constant is individually compared with a criterion value representing the degree of insulation deterioration, and a pass/fail judgment is made based on the correlated diagnosis results, or past insulation breakdown statistical data, the increase rate of capacitance, the dielectric loss rate, This is a method of determining the dielectric breakdown risk rate based on the insulation deterioration constant.

Another invention, an insulation diagnostic device for electrical equipment, includes a sensor that detects leakage current in electrical equipment, and an insulation constant that determines capacitance and dielectric loss rate from the leakage current signal detected by the sensor. an insulation deterioration constant calculation means for calculating a capacitance increase rate and an insulation deterioration constant from the capacitance and dielectric loss factor outputted from the insulation constant calculation means; The rate of capacitance increase and the insulation deterioration constant are individually compared with a criterion value representing the degree of insulation deterioration, and a pass/fail judgment is made based on the correlated diagnostic results, or the statistical data of dielectric breakdown and the rate of increase in capacitance, the rate of increase in capacitance, and the The present invention includes means for diagnosing the insulation deterioration state of an electrical device by determining a dielectric breakdown risk factor based on the dielectric loss factor and the insulation deterioration constant.

(Function) Therefore, by using the above-described means, the method of the present invention detects the leakage current of electrical equipment with a sensor, and then calculates the capacitance and dielectric loss factor, which are insulation constants, from the output of this sensor. . Then, while calculating the capacitance increase rate from the capacitance obtained here and the initial value of the capacitance, using this capacitance increase rate, dielectric loss factor, and each of these initial values, Find the insulation deterioration constant. Furthermore, these capacitance increase rate and insulation deterioration constant are individually compared with judgment reference values to determine pass/fail, or past insulation breakdown statistical data, the capacitance increase rate, the dielectric loss rate, The objective is to obtain a dielectric breakdown risk rate based on the insulation deterioration constant.

Next, by using the above-described means, the device of the present invention calculates insulation constants such as capacitance and dielectric loss factor using the insulation constant calculation means using the detection signal from the sensor that detects the leakage current of the electrical equipment. Thereafter, the rate of increase in capacitance is determined from this capacitance and its initial value, and the insulation deterioration constant is determined using the rate of increase in capacitance, the rate of capacitance loss, and their initial values. Thereafter, the capacitance increase rate and the insulation deterioration constant obtained by this insulation deterioration constant calculation means are individually judged to be good or bad using the determination reference value, or the insulation breakdown statistical data and the capacitance increase rate are evaluated. The insulation deterioration state of the electrical equipment is diagnosed by determining the dielectric breakdown risk factor based on the dielectric loss factor and the insulation deterioration constant.

(Embodiment) Hereinafter, an embodiment of the method of diagnosing insulation of electrical equipment and the apparatus for diagnosing the same according to the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram schematically showing the overall configuration of the present invention. In this figure, reference numeral 11 denotes a power supply unit that applies a predetermined voltage between the conductive part of the electrical equipment to be diagnosed and ground, and when the predetermined voltage is applied from this power supply unit 11 to the electrical equipment, The sensor 12 detects leakage current. The leakage current signal Io detected by this sensor 12 is sent to insulation constant calculation means 13. This insulation constant calculation means 13 uses, for example, a reverse shearing bridge as a high frequency bridge, and calculates the capacitance Cx and dielectric loss factor Tx of the ground insulator of the electrical equipment from the change in the leakage current signal Io. . The capacitance Cx and dielectric loss factor Tx determined by the insulation constant calculation means 13 are sent to the insulation deterioration constant calculation means 14. Unique calculation constants reflecting the insulation configuration of the electrical equipment to be diagnosed are input in advance to the insulation deterioration constant calculation means 14 from the various constant input circuit 15. For example, if the initial values C and T of the capacitance and dielectric loss factor are known, the constant k is input in addition to those initial values C and T, and if the initial values C and T are unknown, the rating of the electrical equipment is input. Voltage,
Empirical values estimated from rated capacity, number of poles, type, etc. are input.

Therefore, the insulation deterioration constant calculation means 14 uses the capacitance Cx and dielectric loss factor Tx from the insulation constant calculation means 13 and the calculation constants from the various constant force circuit 15 to calculate the insulation deterioration constant based on the following calculation formula. seek. In other words, if the rate of increase in capacitance, which is one of the insulation deterioration constants, is C ₀ , it is calculated by the formula C ₀ = Cx/C... (1), and the insulation deterioration constant using the dielectric loss rate is Id. Then, Id=√ C ₀ ² + (kT _x ) ² ...calculated using the formula (2).

Then, the capacitance increase rate C ₀ and the insulation deterioration constant Id using the dielectric loss factor obtained as described above are sent to the pass/fail judgment circuit 16, where a plurality of judgment criteria each representing the degree of insulation deterioration are used. It is compared with the value and judged as to whether it is good, cautionary, bad, etc., and the diagnosis result is displayed on a display unit 17 such as a printer, a recording device, a CR display, etc. Also, capacitance
Cx, dielectric loss factor Tx, capacitance increase rate C ₀ , and insulation deterioration constant Id using dielectric loss factor are displayed on a display unit 18 of a printer, recording device, CRT display, or the like. These display sections 17 and 18 may be displayed using the same display means.

Next, when the insulation deterioration status of high-voltage motors A to D is diagnosed using the configuration of the example described above, the results shown in Figure 2 are obtained regarding the capacitance increase rate _C0 , and the insulation deterioration constant Regarding Id, the results shown in Figure 3 were obtained. As is clear from these figures, C ₀ ,
Id increased, and the diagnosis result gradually increased from a good area to a caution area to a defective area, and finally led to dielectric breakdown.
Comparing Figure 2 and Figure 3, the pass/fail determination method in Figure 3 not only has less variation than the one in Figure 2, but also allows for highly accurate determination of pass/fail based on the correlated diagnostic results of both. can.

Next, another embodiment of the present invention will be described with reference to FIG. That is, in this embodiment, in place of the pass/fail judgment circuit 16 and the display section 17 shown in FIG. 1, a breakdown probability calculation means 21 for determining the dielectric breakdown risk rate and a display section 22 are provided. In other words, this breakdown probability calculation means 21 calculates the insulation deterioration constants Co, Id obtained by the insulation deterioration constant calculation means 14 and the dielectric loss factor obtained by the insulation constant calculation means 13 based on past insulation breakdown performance data. For example, the relationship between Tx and the cumulative frequency of dielectric breakdown is as follows: F(Co)=∫ ^Co _p f(C ₀ ) dC ₀ ……(3) F(Tx)=∫ ^Tx _p f(Tx) dTx ……(4) F (Id) = ∫ ^Id _p f (Id) dId It is calculated from the formula (5) and registered, and compared with the insulation deterioration constant etc. during measurement to determine the dielectric breakdown risk rate.

Incidentally, the results of diagnosis based on this example are shown in FIG. As is clear from this figure, C ₀
In the good range of =1.5 or less, the probability of dielectric breakdown is less than 10%,
In the caution region of C ₀ = 1.5 to 2.0, the dielectric breakdown probability is 10 to
20%, and in a defective region of C ₀ =2 or more, the probability of dielectric breakdown is 20% or more. According to this method, a more detailed diagnosis can be made than the judgment result shown in FIG. 1, that is, the three stages of OK, Caution, and Failure.

Note that the present invention is not limited to the above embodiments, and can be implemented with various modifications.

(Effects of the Invention) As explained above, according to the method of the present invention, the degree of insulation deterioration is determined not only by the rate of increase in capacitance but also by the rate of increase in capacitance and the insulation deterioration constant obtained from the dielectric loss factor. Since each comparison is made with the indicated judgment reference value, two types of diagnostic results can be obtained, for example, as shown in Figures 2 and 3. From these two correlated diagnostic results, the insulation deterioration state of electrical equipment can be determined with high accuracy. Can be judged.

Furthermore, if the dielectric breakdown risk rate is calculated based on past dielectric breakdown statistical data, the capacitance increase rate, the dielectric loss factor, and the insulation deterioration constant,
It is possible to easily grasp the degree of destruction and the probability of destruction. Therefore, it is possible to provide a method for diagnosing the insulation of electrical equipment, which can avoid long-term suspension of the production line based on these diagnostic results, and can improve economic efficiency by performing appropriate maintenance according to pass/fail judgment or dielectric breakdown risk rate.

Furthermore, according to the device of the present invention, not only can the degree of insulation deterioration of electrical equipment be diagnosed easily and with high precision, but also data that can be diagnosed regardless of the range of the power supply voltage from several volts to several kilovolts can be obtained. As a result, a low-voltage, small-sized device can be realized, and the degree of insulation deterioration can be diagnosed safely and easily. This makes it possible to easily and accurately obtain diagnostic results before electrical equipment stops functioning due to insulation deterioration, which prevents long-term production line shutdowns and allows appropriate measures to be taken depending on the degree of insulation deterioration. be able to.

[Brief explanation of the drawing]

1 to 3 are shown to explain an embodiment of the insulation diagnosis method and its diagnostic device according to the present invention, and FIG. 1 is a schematic configuration diagram of the embodiment, and FIG. and FIG. 3 are diagrams for explaining the diagnosis results of the degree of insulation deterioration according to this embodiment, respectively, and FIGS. 4 and 5 are diagrams for explaining other embodiments of the present invention. FIG. 5, which is a schematic configuration diagram of this other embodiment, is a diagram for explaining the diagnosis result of the degree of insulation deterioration according to this embodiment. 11...Power supply section, 12...Sensor, 13...
Insulation constant calculation means, 14...Insulation deterioration constant calculation means, 15...Various constant input circuit, 16...Quality determination circuit, 17, 18...Display section, 21...Destruction probability calculation means, 22...Display section .

Claims (1)

[Claims] 1. After detecting the leakage current of an electrical device with a sensor and calculating the capacitance and dielectric loss factor from the output signal of this sensor using an insulation constant calculation circuit with a high frequency bridge, Obtain the rate of increase in capacitance, the rate of increase in capacitance, and the insulation deterioration constant obtained from the dielectric loss factor, and individually calculate the rate of increase in capacitance and the insulation deterioration constant to a criterion value representing the degree of insulation deterioration. A pass/fail judgment is made based on the correlated diagnostic results compared to the above, or a dielectric breakdown risk rate is determined based on past dielectric breakdown statistical data, the capacitance increase rate, the dielectric loss rate, and the insulation deterioration constant. A method for diagnosing insulation of electrical equipment, characterized by: 2. A sensor for detecting leakage current of electrical equipment; an insulation constant calculation means for calculating capacitance and dielectric loss rate from the leakage current signal detected by the sensor; and a capacitance output from the insulation constant calculation means; An insulation deterioration constant calculation means for calculating a capacitance increase rate and an insulation deterioration constant from a dielectric loss factor, and a judgment reference value representing the degree of insulation deterioration for the capacitance increase and insulation deterioration constant calculated by the insulation deterioration constant calculation means. The pass/fail judgment is made based on the correlated diagnostic results by individually comparing the data, or the dielectric breakdown statistical data and the increase rate of the capacitance, the dielectric loss rate,
An insulation diagnostic device for electrical equipment, comprising: means for diagnosing an insulation deterioration state of the electrical equipment by determining a dielectric breakdown risk rate based on the insulation deterioration constant.