JPH06100526B2 - Method for detecting thermal deterioration of insulation characteristics in electrical equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for detecting the degree of thermal deterioration of an insulating material applied to an electric device.

[Conventional technology]

Generally, a solid insulating material, a liquid insulating material, and a gas insulating material are used alone or in combination for insulating an electric device.

For liquid insulation such as oil-filled transformers and gas insulation such as gas-insulated switchgear, so-called "insulation diagnosis method" based on electrical tests is the main focus.

[Problems to be solved by the invention]

However, in the current insulation diagnosis method based on the electrical test, the test voltage can be applied only up to the rated voltage of the electrical device under test, and thus the changes in various characteristics obtained are small. In particular, since it is affected by humidity, it is empirically only possible to estimate the deterioration status without being able to take a stable response against insulation deterioration.

On the other hand, as a physical method, an insulation lifetime estimation method or the like based on a change in the ratio of the number of hydrogen atoms to the number of carbon atoms in an insulating resin has been proposed. However, these are destructive tests, and the material to be measured must be collected from the insulating layer or a monitor material must be installed in advance in the equipment, and the measuring device is large and unsuitable for on-site measurement. However, there is still a problem such that it is not possible to judge the degree of deterioration over a wide range of insulation deterioration that continuously progresses because it corresponds to the dielectric breakdown voltage that rapidly decreases near the life point. .

Therefore, the present invention has been improved in order to eliminate such drawbacks, and it is possible to perform highly reliable measures such as repairs and updates in the maintenance of electrical equipment with respect to a previously stored database. It is an object of the present invention to provide a simple thermal deterioration measuring method that can be applied to local measurement.

[Means for solving problems]

In order to achieve the object, the present invention deteriorates a sample of the same material as the substance to be measured at various temperatures, obtains the change in hardness due to the deterioration of the sample, and the deterioration temperature based on the Arrhenius velocity reaction equation is given on one axis. And change time of deterioration time are taken, the hardness change is taken on the other axis, and the change of hardness at the various temperatures is plotted on the coordinates represented by the two axes to make a master curve. The degree of deterioration is detected by making the change in hardness of the substance to be measured correspond to the master curve by using the collected covering member of the lead wire as a monitor material.

[Action]

The quantitative change of the chemical structure of the insulating coating of the insulated wire due to heat deterioration depends on the chemical reaction kinetics, while the hardness of the coating is uniquely determined by the chemical structure.

That is, if the change in the chemical structure amount X due to thermal deterioration follows the chemical reaction kinetics, the change in the chemical structure amount X is represented by the following formula (1).

dx / dt = A ・ exp (-ΔE / RT) ・ g (x) (1) However, t: deterioration time, A: frequency factor, ΔE: activation energy, R: gas constant, T: deterioration Absolute temperature, g (x): function representing reaction mechanism Now, assuming that the deterioration of the insulating coating progresses from time 0 to t and the chemical structure amount changes from x ₀ to x, integrating equation (1) gives Equation (2) is obtained.

The integral on the right side of this equation (2) is called the conversion time θ because it is the dimension of time.

Therefore, the equation (2) is transformed into the following equation (4).

In the deterioration region where the function g (x) representing the reaction mechanism and the frequency factor A are constant, even if deterioration occurs under various temperature conditions, if the conversion times θ are equal, the changes in the chemical structure amount X are also equal.
That is, the following relationship is established between the conversion time θ and the change in the chemical structure amount X.

θ = f (x) (5) Further, assuming that the hardness H of the insulator is uniquely determined by the chemical structure amount X, the following formula (6) is provided between the hardness H and the chemical structure amount X.
The relationship is established.

H = h (x) (6) Therefore, the conversion time θ is expressed as a function of the hardness H by the following equation (7).

θ = f {h ⁻¹ (H)} (7) That is, the conversion time θ of thermal deterioration can be obtained from the change in hardness H.

Therefore, if the relationship between the converted time θ of the insulating coating and the deterioration degree of the actual insulation is obtained in advance, the deterioration degree of the actual insulation can be obtained from the change in the hardness H of the insulating coating of the insulated wire.

〔Example〕

The features of the present invention will be specifically described below by taking as an example a low-voltage rotating machine using an insulated electric wire (hereinafter referred to as a "hypalon wire") in which the lead wire is made of chlorosulfonated polyethylene rubber. The low-pressure rotary machine has a structure as shown in FIG. 1 ((a) is a front view of a main part, (b) is a side view). In the figure, 1 is a stator core, 2 is a coil end,
3 is an outlet line and 4 is a bind.

The change in hardness Hs (JIS K6301 spring type) of the insulation coating of the high-palon wire deteriorated in the hot-air circulation type thermostat is represented by the ratio (hardness ratio) to the hardness Hs ₀ before deterioration and is shown in FIG. The change in hardness ratio at each deterioration temperature, for example, 120 ° C. and 150 ° C., is on one line, and there is a good correlation between the conversion time θ of deterioration and the hardness ratio Hs / Hs ₀ .

Now, assuming that the hardness ratio of the insulation coating of the high-palon wire at the position shown in FIG.
As shown in the figure, the conversion time θ corresponding to a hardness ratio of 1.5 is 1.7 ×
It will be 10 ^-7 sec.

Furthermore, set 1.0 as the life point at the position corresponding to θ = 1.7 × 10 ^-7 sec on the same axis of deterioration on the horizontal axis.

Next, the hardness of the high-palon wire at the position shown in FIG. 1A of the low-pressure rotating machine that has been operated for the required time is measured, and the hardness ratio B is determined. The hardness ratio B and the curve C on the vertical axis in FIG. The conversion time D is obtained from the intersection. Furthermore, by making the converted time D correspond to the scale of the deterioration degree, it is possible to detect the remaining life of the low-voltage rotating machine insulation.

In addition to the low-voltage rotary machine insulation using the high-paron wire for the lead wire as described in the above specific embodiments, it is of course applicable to all the rotary machine insulation using other insulated wires for the lead wire,
It can also be applied to detect the degree of thermal deterioration of insulation of other electric devices using insulated wires.

〔The invention's effect〕

As described above, according to the present invention, it is possible to perform repairs and renewal treatments in maintenance of electric devices and the like with high reliability by performing on-site measurement by a simple method.

[Brief description of drawings]

FIG. 1 shows an example of a rotating machine having a covered electric wire whose insulation deterioration degree is measured, FIG. 2 shows conversion time and hardness ratio, and FIG. 3 shows conversion time and deterioration degree and hardness ratio. Show the relationship. 1: Stator core 2: Coil end 3: Lead wire 4: Bind

Claims (1)

[Claims] 1. A sample of the same material as the substance to be measured is deteriorated at various temperatures, and a change in hardness due to the deterioration of the sample is obtained,
One axis is the conversion time of the deterioration temperature and the deterioration time based on the Arrhenius velocity reaction formula, and the other axis is the change in hardness. The change in hardness at the various temperatures is represented by the coordinates represented by the two axes. Electrical equipment characterized by making a master curve by plotting on the above, and using the covering member of the lead wire sampled from the actual machine as a monitor material to detect the degree of deterioration by making the hardness change of the substance to be measured correspond to the master curve. Method for detecting thermal deterioration of insulation characteristics.