JPH06165449A - Winding insulating method - Google Patents

Abstract

(57) [Abstract] [Purpose] Although the varnish is hardened by heating the winding with electricity, the amount of varnish filled in the core slots can be increased and a large amount of varnish adheres to the surface of the core. Prevent that. [Structure] While immersing the stator 1 in the varnish 8,
By heating the winding 3 of the stator 1 with electricity, the varnish 8
In the insulation treatment method for curing the varnish, the varnish 8 has two peaks in the curing temperature characteristic, and the reaction initiation temperature of the peak corresponding to the lower temperature of these two peaks is the slot when the winding 3 is energized and heated. Winding 3 in 2a
Is almost equal to the temperature of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for insulating a winding body, which is an improved method for insulating a winding body such as a stator of a rotary electric machine.

[0002]

2. Description of the Related Art In electrical equipment such as a rotary electric machine, a stator made by winding a wire around an iron core is impregnated with varnish, and the varnish is cured to insulate the stator and fix it. The insulation and heat resistance of the child are improved and the strength thereof is improved. In this case, if the enameled wire is wound, for example, as the element wire of the winding, pinholes permitted by the standard for the enameled wire or the stress applied to the enameled wire during the winding work etc. The damage must be completely covered with an insulating varnish coating.

In many industrial rotary electric machines, external air is sucked into the rotary electric machine, and the sucked air is applied to a winding to cool it. In such a case, external contaminants adhere to the surface of the winding. Here, if the above-mentioned insulation treatment is incomplete, that is, if there is a pinhole not covered with the insulating varnish coating or damage to the coating, the insulation resistance of the winding surface due to moisture absorption of contaminants and deliquescent of salt During the operation of the rotary electric machine, surface tracking may occur from the surface of the winding toward the iron core (earth), which may cause a short circuit between the ground or between the windings, resulting in a burnout accident.

As a countermeasure against this, conventionally, there is a structure in which a varnish treatment with a large amount of special adhesion is applied to the winding. According to this configuration, the environment resistance effect is also increased, and therefore it is often used. However, with this configuration, there are problems that the number of work steps increases and the time required for the work increases.

As a structure for solving such a problem,
There is a structure described in Japanese Patent Application No. 60-51710. In this structure, a stator composed of an iron core and a winding is dipped in the varnish, and the winding is electrically heated to cure the varnish by the heat generated from the winding.

[0006]

However, in the above-mentioned conventional structure, the heat generated from the winding housed in the slot of the iron core is transferred to the iron core and is radiated, so that the temperature of the winding in the slot of the iron core is radiated. Is lower than the temperature of the coil end of the winding. Therefore, while the varnish adheres thickly at the coil end, the varnish hardly gels in the slots of the iron core due to the low temperature, and the viscosity of the varnish is further increased during the heat curing performed in the subsequent step. There is a drawback that the varnish is lowered and flows out from the slot of the iron core, and the amount of the varnish filled in the slot is small. When the filling amount of varnish in the slot becomes small, air intervenes between the winding and the iron core slot, so that heat of the winding becomes difficult to be transferred to the iron core, and the cooling performance of the winding deteriorates. Occurs.

On the other hand, it is conceivable to use a varnish that starts to cure at a low temperature, but when such a varnish is used, a large amount of varnish adheres to the inner and outer surfaces of the iron core, and There is a problem that the work of removing the attached varnish must be performed. For this reason,
In practice, it was not possible to use varnishes that start to cure at low temperatures.

Therefore, the object of the present invention is to harden the varnish while electrically heating the winding, but it is possible to increase the amount of the varnish filled in the slots of the iron core, and further, to increase the amount on the surface of the iron core. Another object of the present invention is to provide a winding body insulation treatment method capable of preventing the varnish from adhering.

[0009]

According to a method of insulating a winding body of the present invention, a winding body composed of an iron core and a winding housed in a slot of the iron core is impregnated with varnish, and In the insulation treatment method of the winding body, which is obtained by curing the varnish by heating by applying electricity, the varnish is
Where the curing temperature characteristic has a plurality of peaks, and the reaction initiation temperature of the peak corresponding to the lowest temperature of the plurality of peaks is substantially equal to the temperature of the winding in the slot during energization heating of the winding. It is characterized by

In this case, it is conceivable that the varnish is constituted so that the curing temperature characteristic has two peaks by adding a low temperature curing catalyst and a high temperature curing catalyst.

It is also preferable that the varnish is added in a state where the curing catalyst is contained in a capsule that melts at a plurality of temperatures, so that the curing temperature characteristic has a plurality of peaks.

[0012]

According to the above means, the curing temperature characteristic of the varnish has a plurality of peaks, and the reaction initiation temperature of the peak corresponding to the lowest temperature of the plurality of peaks is Since the temperature of the winding in the slot is set to be approximately equal to that of the winding, the varnish cures quickly when the winding is heated by electricity, even if the temperature of the winding placed in the slot of the iron core is low. Its viscosity increases. Therefore, in the case of heat curing performed in a later step,
The varnish will no longer flow out of the slots of the iron core, and the amount of varnish filled in the slots will be sufficiently large. Therefore, the cooling performance of the winding is also improved.

Since the temperature of the inner and outer surfaces of the iron core is lower than the temperature of the winding in the slot of the iron core,
The amount of varnish that hardens on the surface of the iron core decreases,
The optimum amount of varnish will adhere to the surface of the iron core.
In addition, the temperature of the coil end part of the winding becomes sufficiently high, and the peak of the curing temperature characteristic corresponding to the high temperature causes
Since the hardening progresses rapidly, the varnish adheres to the coil end portion of the winding in a sufficiently thick manner.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, with reference to FIG. 4, a schematic configuration of a stator 1 of a rotary electric machine, for example, as a winding body of an electric device will be described. The stator 1 is formed by winding a plurality of windings 3 around a stator core 2 and has a substantially annular shape as a whole. Among these, the stator core 2 is formed by laminating a plurality of thin steel plates having, for example, a ring shape and a plurality of open slots 2a formed on the inner diameter side. A slot insulator 4 is provided on the inner surface of the slot 2a.

On the other hand, the winding 3 is formed by winding a wire such as an enamel wire, and a plurality of the windings are housed in a predetermined slot 2a of the stator core 2 and fixed by a wedge (not shown). Is wound around the stator core 2.

The stator 1 thus constructed is subjected to a varnish impregnation hardening treatment as will be described later, and as a result, the entire surface, between the wires of the winding 3, and between the winding 3 and the slot 2a. Between (slot insulator 4),
An insulating layer of varnish is formed. As a result, the heat resistance strength and vibration resistance strength of the winding wire 3 are improved, the fixing force to the stator core 2 is strengthened, insulation deterioration is prevented, and the cooling performance is improved.

Now, the procedure of the varnish impregnation curing treatment for the stator 1 will be described with reference to FIGS. 1 to 3 and FIG.

First, as shown in FIG. 2, the lead terminal 5 of the winding 3 of the stator 1 and the power output terminal 6a of the electric heating device 6 are provided.
And the temperature sensor 7 connected to the temperature detection signal input terminal 6b of the electric heating device 6 are attached to the coil end portion 3a of the winding 3. When the energization start switch 6c is turned on, the energization heating device 6 energizes the winding 3 with a three-phase alternating current and raises the temperature of the winding 3 by Joule heat. Then, the electric heating device 6 receives the temperature detection signal from the temperature sensor 7, and controls the turning on and off of the winding 3 so that the temperature of the coil end portion 3a of the winding 3 is maintained at the set temperature.
Alternatively, the magnitude of the current (or voltage) flowing through the winding 3 is variably controlled.

The set temperature of the electric heating device 6 can be set to a desired temperature by rotating the temperature setting dial 6d of the electric heating device 6. In this case, the set temperature is set to 130 ° C., for example.

In this embodiment, before the stator 1 is dipped in varnish, the winding 3 is energized by the energization heating device 6 to raise the temperature of the winding 3 in advance. And
When the temperature in the slot 2a of the stator core 2 of the winding 3 reaches approximately 90 ° C (that is, the temperature detected by the temperature sensor 7 at the coil end portion 3a of the winding 3 is 130 ° C), the temperature of As shown, the stator 1 is placed in a varnish container 9 containing a varnish 8. In this case, the stator 1 is installed in the varnish container 9 so that the axial direction of the stator 1 is along the up-down direction (such a varnish dipping method for the stator 1 is referred to as vertical dipping). .

Here, the varnish 8 has a plurality of, for example, two peaks in the curing temperature characteristic (that is, curing exothermic characteristic), and the reaction initiation temperature of the peak corresponding to the lower temperature of these two peaks is the winding. The temperature of the winding wire 3 in the slot 2a is set to be substantially equal to that of the winding wire 3 during heating by energization. The curing temperature characteristic of the varnish 8 used in this example is specifically shown by the solid line A in FIG. The graph of FIG. 1 is the result measured by DSC (differential scanning calorimetry), the vertical axis represents the heat generation rate during curing, and the horizontal axis represents temperature (time).
Is shown. In the above measurement experiment, the temperature was 5 ° C in 1 minute.
It was measured under rising conditions.

As is clear from the solid line A in FIG. 1, the curing temperature characteristic of the varnish 8 has a small peak at about 90 ° C. and a large peak at about 150 ° C. In the case of the present embodiment, the varnish 8 contains, for example, an epoxy resin as a main component, and a low temperature curing catalyst and a high temperature curing catalyst are added thereto to generate the above two peaks. Further, in the above embodiment, the reactivity of the varnish 8 as a whole is lowered by making the amount of the low temperature curing catalyst relatively small. The curing temperature characteristic of the varnish having the conventional structure is shown by a broken line B in FIG. As can be seen from the broken line B, the curing temperature characteristic of the varnish having the conventional structure has only one large peak in the vicinity of 120 to 130 ° C.

When the stator 1 is immersed in the varnish 8, the stator 1 is slowly lowered and immersed. At this time, the lowering speed of the stator 1 is three-phase induction motor (4P-
2.2 kW), specifically, 30 to 50
cm / min. By making the speed low in this way, the air existing in the slots 2a of the stator core 2 is pushed out by the infiltration of the varnish 8 and is replaced with the varnish 8, so that the air in the slots 2a Is fully filled with varnish 8. The specific value of the descending speed of the stator 1 is appropriately set according to the space factor of the winding 3 in the slot 2a and the like.

Then, after the stator 1 is completely immersed in the varnish 8 and, for example, 10 minutes have passed, the stator 1 is pulled out of the varnish 8. The necessary amount of varnish 8 adheres to the stator 1 by the immersion time of 10 minutes. More specifically, the temperature of each portion of the stator 1 after the winding 3 starts to be energized and heated changes as shown in FIG.
In the graph of FIG. 3, the solid line C indicates the temperature of the stator core 2, the solid line D indicates the temperature of the winding 3 in the slot 2a of the stator core 2, and the solid line E indicates the coil end portion 3a of the winding 3. Shows the temperature of.

As can be seen from the graph of FIG. 3, the temperature of the stator core 2 is raised to about 80 ° C. by heating the winding 3 by energizing it while the stator 1 is immersed in the varnish 8 for 10 minutes. The temperature of the winding 3 in the winding 2a is about 100 ° C, and the temperature of the coil end portion 3a of the winding 3 is about 130 ° C. In this case, the reason why there is a difference in temperature between the parts is that the heat capacity of the stator core 2 is large.

Since the temperature of each part of the stator 1 is as described above and the varnish 8 has the curing temperature characteristic as shown in FIG. A film of varnish 8 having a thickness of about 30 μm is adhered and formed, and a sufficient amount of varnish 8 is filled in the slot 2a and hardened into a gel state. Will be attached relatively thickly.

Thereafter, after the stator 1 is pulled out of the varnish 8, the stator 1 is heated by a hot air drying oven or an induction heating oven (neither is shown) to completely remove the varnish 8 attached to the stator 1. To cure. In this case, slot 2a
The varnish 8 filled inside has already hardened into a gel state and has almost no fluidity, so that the varnish 8 will not flow out from the inside of the slot 2a during heat curing by the furnace. Therefore, the varnish 8 in the slot 2a
The filling rate of is improved to about 100%.

Further, the temperature of the coil end portion 3a is almost 1
While the temperature of the second peak of the curing temperature characteristic of the varnish 8 is about 150 ° C. while the temperature of the varnish 8 is about 30 ° C., the varnish 8 is comparatively hardened in a gel state at the coil end portion 3a while being relatively cured. It adheres only thickly and does not adhere more than necessary.

Furthermore, since the temperature of the stator core 2 is about 80 ° C., which is lower than the temperature of the first peak of the curing temperature characteristic of the varnish 8 (about 90 ° C.), the surface of the stator core 2 is low. Then, the curing reaction of the varnish 8 hardly proceeded, and 10
Only the film of the varnish 8 having a thickness of about 30 μm is attached. Therefore, the work of removing the varnish adhering to the inner and outer peripheral surfaces of the stator core 2 is completely unnecessary.

Here, the effect of improving the filling rate of the varnish 8 into the slot 2a to about 100% in this embodiment will be described in comparison with the conventional structure. That is, since the filling amount of the varnish 8 in the slot 2a is sufficient, air is not present between the winding 3 and the slot 2a, and the heat of the winding 3 is easily transferred to the stator core 2. The cooling performance of the winding 3 is improved. Specifically, when the saturated value of the temperature rise due to the long-time rated load operation is obtained by an experiment and the difference from the saturated value of the temperature rise of the conventional district administration is calculated, the difference becomes 10 to 20 ° C. I found out. From this experimental result, it can be seen that it is effective in downsizing and cost reduction of the electric motor.

Further, in the above embodiment, the coil end portion 3
By attaching the varnish 8 to a with a necessary and sufficient thickness, the environment resistance is improved as compared with the conventional configuration. As a test of the environmental resistance, for example, a powder obtained by mixing powder of, powder of carbon and salt with water and applied as a contaminant to the coil end portion 3a of the winding 3 and dried, and then 40 ° C. 85% It was exposed to the humidity of RH and the change in the ground meg (ground insulation resistance) was measured. The measurement result is shown in the graph of FIG. In FIG. 5, the solid line F shows the winding 3 of this embodiment, and the solid line G shows the winding of the conventional configuration.

As is clear from the graph of FIG. 5, the winding 3 of the present embodiment can cover 100% of the machining scratches generated in the coil end portion 3a and insulate the coil 3 from the ground. It can be seen that it is 100 to 1000 times higher than the configuration.

Further, in the above embodiment, before the stator 1 is dipped in the varnish 8, the energization heating device 6 starts energizing the winding 3 to raise the temperature of the winding 3 in advance. Therefore, the following respective effects occur. That is, since the winding 3 is heated in the atmosphere and the insulating film of the wire of the winding 3 is annealed by the heating temperature, the varnish 8 causes crazing or cracks in the insulating film (this is generally called a solvent shock). Can be prevented.

Further, since the winding 3 is heated in the atmosphere, the amount of heat taken by the varnish 8 can be reduced, and the heating time required to raise the temperature to the set temperature can be shortened. Furthermore, since the heating time of the winding wire 3 in the varnish container 9 can be shortened, the temperature rise of the varnish 8 in the varnish container 9 can be suppressed to a minimum and the so-called pot life can be lengthened. Furthermore, since the temperature rise of the varnish 8 can be suppressed, the time for cooling the varnish 8 by the cooling device can be shortened and the varnish processing cycle can be improved.

In the above embodiment, when setting the curing temperature characteristic of the varnish 8 as shown in FIG. 1, it was realized by adding a low temperature curing catalyst and a high temperature curing catalyst to the varnish 8, but this is not the only option. However, the curing temperature characteristic may have two peaks, for example, by adding the curing catalyst in a state of being contained in a capsule that melts at two temperatures.

Further, it may be constituted by mixing two or more kinds of varnish (resin). Specifically, it is conceivable that the unsaturated polyester, which starts the curing reaction at a low temperature, and the epoxy, which reacts at a high temperature, are mixed in an appropriate ratio. Furthermore, the curing catalyst required for epoxy is, for example, 20%.
Alternatively, the curing catalyst may be added as usual, and the remaining about 80% may be added to the curing catalyst in a capsule that melts at high temperature.

Furthermore, in the above embodiment, the curing temperature characteristic of the varnish 8 is applied to a structure having two peaks.
Instead, it may be applied to a configuration having three or more peaks. In this case, for example, if the curing catalyst is added while being contained in a capsule that melts at a plurality of temperatures, a configuration having a plurality of peaks can be easily realized. In addition, it may be applied to a structure having a wide peak in which two peaks are overlapped.

Further, in the above embodiment, when the winding 3 is electrically heated, it is heated by the three-phase AC power supply, but it may be heated by the DC power supply or the AC power supply having a frequency higher than the commercial AC power supply frequency. Furthermore, in the above embodiment, the temperature sensor 7 detects the temperature of the coil end portion 3a of the winding 3. However, the present invention is not limited to this, and the resistance or impedance of the winding is measured to detect the temperature. Alternatively, the temperature may be detected in a non-contact manner with a radiation thermometer or the like. Furthermore, in the above embodiment, the varnish 8 is made of epoxy resin, but it goes without saying that it may be made of other resin such as acrylic resin.

[0039]

As is apparent from the above description, the present invention shows that the varnish has a plurality of peaks in the curing temperature characteristic and that the reaction initiation temperature of the peak corresponding to the lowest temperature among the plurality of peaks. Is almost equal to the temperature of the winding in the slot of the stator core when the winding is energized and heated, so that the varnish is hardened while the winding is energized and heated, but it is filled in the slot of the iron core. It is possible to increase the amount of varnish to be used and to prevent a large amount of varnish from adhering to the surface of the iron core.

[Brief description of drawings]

FIG. 1 is a graph showing a curing temperature characteristic of a varnish showing an example of the present invention.

FIG. 2 shows that the stator is housed in a varnish container,
A vertical sectional front view schematically showing a state in which a winding is electrically heated.

FIG. 3 is a graph showing a change in temperature of each part of the stator after the heating of the winding by energization is started.

FIG. 4 is a schematic vertical sectional front view of a stator.

FIG. 5 is a graph showing changes in insulation resistance to ground.

[Explanation of symbols]

1 is a stator, 2 is a stator core, 2a is a slot, 3 is a winding wire, 6 is an electric heating device, 7 is a temperature sensor, 8 is a varnish,
9 indicates a varnish container.

Claims (3)

[Claims] 1. A varnish is impregnated into a winding body composed of an iron core and a winding housed in a slot of the iron core, and
In a method for insulating a winding body, which comprises curing the varnish by heating the winding by applying current, the varnish has a plurality of peaks in curing temperature characteristics and is the lowest of the plurality of peaks. A method for insulating a winding body, wherein a peak reaction start temperature corresponding to a temperature is substantially equal to a temperature of the winding wire in the slot when the winding wire is energized and heated. 2. The winding according to claim 1, wherein the varnish has a curing temperature characteristic having two peaks by adding a low temperature curing catalyst and a high temperature curing catalyst. Body insulation treatment method. 3. The varnish is configured to have a plurality of peaks in curing temperature characteristics by adding a curing catalyst in a state of being contained in a capsule that melts at a plurality of temperatures. Item 2. A method for insulating a winding body according to Item 1.