JPH0123054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining the leakage index of impregnated resin for high-pressure rotating machine insulation.

In recent years, insulation methods for high-voltage rotating machines have become mainstream, in which the coil and core are integrally impregnated under vacuum pressure. This insulation method has the following problems in the curing process compared to the case where the coil itself is vacuum-pressurized and impregnated to cure it. That is, since the coil and core are integrated, the heat capacity is large and it takes a long time to reach a certain temperature. For this reason, the curing of the impregnated resin is delayed, and the resin tends to flow out. Due to the resin flowing out, voids are formed in the insulating layer, causing insulation defects. Therefore, it is very important for quality control to quantitatively understand the degree of resin leakage. However, in the past, it was not possible to quantitatively grasp the extent of this leakage, making quality control very difficult.

The purpose of the present invention is to sample the temperature of a product in a drying oven at regular time intervals, and use a computer to detect leakage of the resin based on this sampling data, the temperature-viscosity characteristics of the impregnated resin, and an experimental formula showing the viscosity change at a constant temperature. The objective is to quantitatively grasp the degree of leakage of the resin by determining the index.

The method for calculating the resin leakage index will be explained below.
The change in viscosity of any resin over time at a constant temperature is as shown in FIG. 1. Therefore, the change in viscosity over time can be expressed by the following equation.

η _t = f _(t) - (1) t: time f: function In addition, the temperature viscosity characteristics of any three types of resins that exhibit a viscosity of η _Tp at To℃ are as shown in Figure 2, and are expressed by the following formula: It can be expressed as

η _T = g _(T) + (η _Tp − g _(Tp) ) - (2) T: Temperature g: Function On the other hand, the Arrhenius equation holds for the resin curing reaction amount, temperature, and time, and the following equation holds: shown.

Int ₁ = ΔE/R (1/T ₁ - 1/T ₂ ) + Int ₂ - (3) t ₁ , t ₂
; Time T ₁ , T ₂ ; Temperature R; Gas constant ΔE; Activation energy Now, by setting the standard temperature as Ts and finding the viscosity change formula at the standard temperature, it can be expressed by the following formula, similar to formula (1). .

ηst=fs(t)−(4) The viscosity of a resin having a viscosity ηx at an arbitrary temperature Ta°C after a short time Δts has passed from time tx can be determined as follows. The Δtx time at Tx°C is converted using the following formula at the standard temperature Ts°C using equation (3).

InΔtsx=ΔE/R(1/Tx−1/Ts)+In(Δtx)—
(5) Δtsx: Δtx converted to standard temperature Also, tx is similarly converted as follows.

Intsx = ΔE/R (1/Tx - 1/Ts) + In (tx) - (6) tsx; Converted to standard temperature The viscosity of the resin at standard temperature after (tsx + Δtsx) has passed is calculated using equation (4). It can be calculated using the following formula.

ηs (tx + Δtx) = fs (tsx + Δtsx) - (7) ηs (tx + Δtx) Viscosity after (tsx + Δtsx) has elapsed at standard temperature The viscosity at standard temperature can be converted to the viscosity at Ta℃ using equation (2) using the following formula. It can be expressed as

ηa (tx + Δtx) = g (Ta) + (ηs (tx + Δtx) − g _(Ts) ) - (8) ηa (tx + Δtx); Viscosity after (tx + Δtx) at Ta℃ According to the above calculation method, the curing process The change in viscosity of the resin can be easily calculated. Here, the following equation is defined as the resin leakage index.

IND=∫ ^t _p 1/ηdt - (9) IND; Leakage index Equation (9) can be approximated by the following equation.

IND≒ _o 〓 ⁱ⁼¹ Δti/ηi - (10) where Δt ₁ = Δt ₂ =...=Δti =...Δtn=t/n On the other hand, ηi in equation (10) can be calculated by equation (8) Therefore, equation (10) can be easily calculated. As is clear from equation (9), the larger the value of the leakage index IND, the more likely it is to leak. Note that it is usually sufficient to consider the functions f and g used in equations (1) and (2) to be cubic equations.

Examples of the present invention will be described below. Now, if we draw a graph of temperature change over time for any product A in the drying oven, it will be as shown in Fig. 31. When this product is impregnated with any three types of resin, the graph of the viscosity change over time in the drying oven for each resin is shown in Figure 4 2-1, 2-
It becomes 2, 2-3. In addition, these resins,
, when the leakage index of
becomes. In addition, 2-1, 3-1 are resin, 2-
2 and 3-2 use resin, and 2-3 and 3-3 use resin. Here, it can be seen that resin has the lowest leakage index, and therefore products impregnated with resin are of the best quality. According to the present invention, the degree of resin leakage can be quantitatively determined by the method described above, so that the quality of the product can be determined.
It has the advantage that it is easy to judge whether or not to use the product, and it can also be useful for quality control.

[Brief explanation of drawings]

Figure 1 is a graph of the viscosity change over time of an arbitrary resin at a constant temperature, Figure 2 is a graph of temperature-viscosity characteristics of three types of arbitrary resins, and Figure 3 is a graph of the resin in the drying oven in the example. A graph of the change in leakage index over time and a graph of temperature change over time of Product 1 in the drying oven, Fig. 4 shows the resin in Example.
2 is a graph of viscosity change over time in a drying oven.

Claims (1)

[Claims] 1. A first step of sampling the temperature of the product or the impregnated resin at fixed time intervals in the heat curing process of the impregnated resin for high-pressure rotating machine insulation;
Determining the leakage index of the resin in the drying oven, which consists of a second step of calculating the leakage index of the resin using a computer from the process results, the temperature viscosity characteristics of the impregnated resin, and an experimental formula showing the viscosity change characteristics at a constant temperature. Method.