JPS5984921A - Method for determining curing time of resin in drying oven - Google Patents

Abstract

PURPOSE:To omit wasteful holding time and shorten the operating time, by sampling a product temperature at a given time interval in a drying oven, calculating the curing reaction index from the resultant data using a computer, and determining the proper curing time of the resin. CONSTITUTION:In a hot-curing process of an impregnated resin for high-voltage insulation of high-voltage rotating machines, the temperature of the product or impregnated resin is sampled at a given time interval, and the curing reaction index indicating the curing degree of the resin is calculated using a computer. Thus, the proper curing time is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for determining the curing time of an impregnated resin for high-pressure rotating machine insulation during the process of heating and curing the resin.

In recent years, insulation methods for high-voltage rotating machines have become mainstream, in which the coil and core are integrated and impregnated under vacuum and 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, it takes a long time for the heat capacity to reach a certain temperature. When completely curing the impregnated resin, it takes a short time for the product to reach a certain temperature for products with a small heat capacity, so it is the same as when the product reaches a certain temperature and then is impregnated and cured using a single coil under vacuum pressure. There is no big problem in how to hold and layer the time. However, products with large heat capacities require a long time to reach a certain temperature. In conventional methods, the curing reaction valve of the resin, which progresses until it reaches a certain temperature, is ignored, so the degree of curing to this point is not known, and in the trench where the curing reaches a certain temperature even though the curing is actually progressing. Assuming it has not cured at all, is it held for the same amount of time as when the coil itself is impregnated with vacuum pressure and cured after reaching a certain temperature? I've been doing it. For this reason, a holding time much longer than that required for actual complete curing was required.

The purpose of the present invention is to sample the temperature of a product in a drying oven at regular time intervals, use a computer to calculate a curing reaction index representing the degree of curing of the resin from this sampling data, and calculate the curing reaction that progresses below a set temperature. By correctly evaluating the curing reaction index and stopping the drying oven when the curing reaction index reaches a certain value (completely curing), an appropriate curing time can be obtained and the working time can be shortened.

Below is how to calculate the curing reaction index? explain.

If the curing reaction rate of resin at 20°C is iVs,
The amount of curing reaction within time t at 20° C. can be expressed by the following formula.

W-Vs
= 1) Define the curing reaction index per hour as W=lXl=1. On the other hand, the Arrhenius equation can be applied to the resin curing reaction to obtain a constant amount of curing reaction.

The following relationship holds between temperature and time.

t i Reaction time at Ts”C AE H activation energy R; gas constant Assuming that the product is heated to a temperature as shown in Figure 1 in the drying oven, tl (ti + mut) ( D
The curing reaction amount of the resin in between is calculated as follows:
Let the temperature after ti time be Ti'C. Add 1 to Ti'C and get 4 to obtain the same amount of reaction as the reaction index that proceeds in time 2
The reaction time at 0°C can be calculated from equation (2) as follows.

, El+ LatL-R(Ts-ball)"rnΔt (')Δt
i; m converted to 20° C. Therefore, the amount of curing reaction ΔWi that progresses between ti and (ii+t) is divided as follows using equation (1).

AW4'l夙Al,,t・(4) Therefore, the total hardness fhi reaction index Wt after (mutXn) time from the start of curing
otal is calculated as follows.

Wtatal = 1. y chimi 1
(I xby:i) (t)L+j
When i''I Wtotal reaches a certain value, the resin is considered to be completely cured, and heat curing is stopped.

The present invention will be explained in detail below. Graph tl of the temperature increase pattern with respect to the passage of time in the drying oven for two arbitrary products A and B is shown in FIG. Said A.

B! ! The graph of FIG. 3 is obtained by dividing the curing reaction index (σ) for each product using the above equation (5). From FIG. 3, it can be determined that product A was completely cured in 30.5 hours, and product B was completely cured in 52 hours. Corresponding these to Figure 2, for the product A, 1 is the time to finish curing and 2 is the time suitable for a constant temperature, and for product B, 3 is the time to finish curing and 4 is the time when the constant temperature is reached. It's time.

From this figure 2, it can be seen that in the conventional method, it was assumed that curing started when a certain temperature was reached, and the holding time was set aside for the curing time required when the coil alone was impregnated with vacuum pressure and cured. All things considered, using the present invention:
Conventionally, the product A has been shortened by the time between 1 and 2 (2 hours) compared to the conventional holding time, and the product B has been shortened by 3 to 4 leaps (10 hours) from the conventional holding time. , it is done.

According to this invention, it is possible to know the appropriate curing time for the resin regardless of the heat capacity by using the method described above, so that the conventional wasteful holding time can be eliminated, one working time can be shortened, and the working time can be reduced. It is possible to streamline the process, and it can also be useful for process and management quality control.
There are some advantages.

[Brief explanation of the drawing]

Figure 1 is a graph of the temperature increase pattern of any product in the drying oven, Figure 2 is a graph of the temperature increase pattern of arbitrary products A and H in the drying oven, and Figure 3 is product A in Figure 2.
, B is a graph showing the relationship between the heating time in the drying oven and the hardening reaction index calculated according to the present invention.0 Applicant Shinko Electric Co., Ltd. Agent Patent Attorney Haruya Saito

Claims (1)

[Claims] In the heat curing process of impregnated resin for heavy pressure rotating machine insulation,
It consists of a first step of sampling the temperature of the product or impregnated resin at regular time intervals, and a second step of using a computer to calculate a curing reaction index representing the degree of curing of the resin based on the results of the first step. Method for determining curing time of resin in drying oven.