JPS5838875A - Device to test insulation between turns - Google Patents

Abstract

PURPOSE:To detect good or no good of the insulation between turns easily and accurately by applying impulse voltage only to one group of windings and grounding the other groups of windings and judging good or no good based on the difference of applied voltage wave shapes and so on. CONSTITUTION:An impluse voltage is applied to the U-phase windings of a plurality of groups of windings 3 through an impulse voltage generator 1, wave shaping circuit 2 and a switch 6, and the other V- and W-phase windings are grounded. The wave shape of this applied voltage wave shape is stored in a memory 8 through a frequency divicer 7, etc. Next, when the impulse voltage is applied only to the V-phase windings by changing over a switch 6, the difference of the wave shape and the previous applied voltage wave shape is displayed on a display device 5, and with the defect in insulation which is judges by a difference over a specified value an output for alarming or warning display is generated from a wave shape comparator 9. This also applies when seeing the sum of wave shapes of impulse voltages that have different polarities and using current wave shapes in place of the actual voltage wave shapes, and the sensitivity does not drop in the case of unbalance due to induction among the windings. Good or no good of insulation among turns can be, therefore, easily and accurately detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a test device that applies an impulse voltage to a winding of an electrical device and determines the quality of the insulation of the winding, particularly the insulation between turns.

When applying an impulse voltage to both ends of a winding in which a large number of insulated wire rings are connected directly or in series and parallel to determine the quality of the winding between the turns, even if one of the turns is short-circuited, the voltage will not increase. Changes in the voltage waveform or current waveform at the application terminal are small, and it is often difficult to detect defects. Therefore, various methods have been studied in the past, but most of them are characterized by the use of symmetrical two-winding groups, and can be broadly classified into the following two. That is, one method is to apply two symmetrical circuits: Inno (luminium pressure) alternately, superimpose both waveforms on the cathode ray tube of an oscilloscope, and observe whether the two waveforms match.Both windings If there is no abnormality anywhere in the group, the two waveforms will match, and if there is an abnormality, one waveform will change slightly.However, in some cases, the change is so small that it is difficult to judge whether the two waveforms have shifted relative to each other. To compensate for this drawback, impulse voltages are simultaneously applied to two symmetrical winding groups, and the waveform of the difference between the two applied voltages or the waveform of the difference between the two applied currents is observed using an oscilloscope. If there is a defect in one of the winding groups, the waveform of that circuit will change, so by amplifying and observing the difference between the waveforms of both circuits, it is possible to determine with good sensitivity whether the winding is good or bad. .A conventional system for implementing this method is shown in 1g, 11) is an impulse voltage generator, 0 is a waveform adjustment circuit that divides the impulse voltage into two and adjusts the waveform, and 13) is a stator of a rotating electric machine. It is a winding wire connected in a star shape and has terminals ty, v, and w, and a terminal U.

Connect so as to apply an impulse voltage to ①, and connect ＠W to ground. (4) is a circuit for obtaining a differential waveform between both applied voltages, and (5) is a waveform display. When observing waveform differences using this conventional device, if the circuit is completely symmetrical, the difference between the U and V phase terminal voltages should be almost zero. Of course, there are many fixed child windings that do this, but there are also cases where the balance between the two phases is poor.

This may occur for the following reasons even if there is no abnormality in the insulated wire. As an example of electromagnetic induction between the wires in the stator winding in Figure 1, the wire closest to the track side (hereinafter referred to as the first wire) and the first wire have the strongest influence. There is a strong inductive effect between the wire rings, for example, the wire rings that are inserted in the same nist and are connected to the upper coil and the lower coil. This induction is shown by a broken line arrow in FIG. 1, but if this induction is taken into account, the U-phase and V-phase may no longer be symmetrical circuits. To judge the quality of the turn insulation of the stator winding of a rotating electrical machine where this phenomenon occurs strongly,
This becomes somewhat difficult with the conventional device shown in FIG.

An object of the present invention is to easily and reliably detect the presence or absence of insulation defects between turns of electrical equipment windings.ii! The aim is to provide a

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 112. (2) is a waveform adjustment circuit that adjusts the voltage waveform generated by the impulse voltage generator (2), and ts) is the stator winding of the rotating electric machine under test, which is connected in a star shape. It has U, V, and W terminals, and terminal W is grounded.

(6) is connected to apply impulse voltage to one of the terminals U and V of both U-phase and ■-phase winding groups, ground the other terminal, and connect the impulse voltage application terminal (7) is a voltage divider that divides the impulse voltage for observation. (8) is a waveform storage device that calculates the difference or sum of input waveforms due to the impulse voltage, In this case, it is connected to the voltage divider (7),
A waveform indicator (9) that displays the difference or sum of the waveforms on the output side and a waveform comparator (9) that displays the display or issues an alarm when the difference or sum of the waveforms exceeds a predetermined reference value are connected. do.

Next, the effect will be explained.

As a first method of using this device, a case will be described in which a difference between waveforms is determined. When the impulse voltage generator (1) generates an impulse voltage, the wavefront length of the impulse voltage is adjusted by the waveform adjustment circuit (2) to a predetermined value, for example, 1 μS, and then passes through the switch 16) to one phase of the winding. is applied to In this case, since the other two phase terminals are grounded, which phase
Even if voltage is applied to the phase, the test rotating basket aiU
If you look at the IA stator windings, they are exactly the same, and if the windings are completely sound, the applied voltage waveforms should be the same.

For example, a voltage is first applied to the U phase, and the voltage waveform is stored in the waveform storage device 8). Next, switch the switch (6), apply voltage to the ■ phase, and store the waveform in the waveform storage device (8).
, the waveform is subtracted from the waveform of the U-phase applied, and the waveform is amplified and displayed on the waveform display (5) (: and the waveform comparator 19) compares it with a predetermined reference value. If there is no abnormality in the winding, this differential waveform is almost at zero level. If there is an abnormality in the winding, the differential waveform will deviate from the zero level, so if you look at the waveform displayed on the waveform display (5), you can judge with good sensitivity whether it is defective or not, and you can compare the waveforms. The container (9) also compares with a predetermined reference value and brightens this reference value,
When it is determined that the product is defective, a message to that effect is displayed or a warning is issued, so that even an unskilled person can make the determination.

A second method using the apparatus shown in FIG. 2, in which the sum of waveforms is determined, is as follows.

The method is the same as the first method by first applying a positive impulse voltage to the U phase, then applying a negative impulse voltage of the same shape to the V phase, and adding both waveforms in the waveform storage device (8). Sensitivity can detect defects in turn insulation.

In addition, although all of the above explanations have been made for windings with star-shaped connections in the drawings, tests can be conducted in the same way for triangular-connected windings, or even other types of windings that have winding groups with the same specifications. Can be done.

Next, another embodiment will be described with reference to FIG.

In Fig. 2, the voltage waveform was measured, but in this example, the applied current waveform that flows when an impulse voltage is applied is derived by the current transformer a, and this is separately calculated as in the example of Fig. 2. The difference or sum of the current waveforms applied to the two phases is determined by the waveform storage device (8), and the waveform display (instantly displayed)
The determination is made using a waveform comparator (9).

Even in this case, the test can be carried out in the same manner as in the embodiment shown in FIG.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings; for example, the device for determining whether the device is good or bad may include both the waveform display (stopped) and the waveform comparator (9) at the same time. It goes without saying that the broom may be equipped with only one side instead of the other, and that it can be modified in various ways without changing the gist of the broom.

As explained above, according to the present invention, when testing the inter-turn insulation of a winding that has a plurality of winding groups with the same specifications, an impulse voltage is applied only to the windings of one group, and the other windings are The wire is grounded, the applied voltage or applied current is stored in a waveform storage device, and then an impulse voltage is applied only to another group of windings, and the waveform of the applied voltage or applied current and the 11L loop that has been stored once are By taking the sum (in the case of − unipolar impulse voltage application) or the sum (in the case of reverse polarity impulse voltage application) and determining whether it is good or bad from the waveform, the conventional 2T#A1! Unlike the case of simultaneous application, there is a great advantage in that it is possible to reliably detect defects in insulation for one unit of insulation without reducing detection sensitivity due to imbalance due to induction between different groups.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional turn-type insulation testing device. Ia and FIG. 3 are circuit diagrams showing different embodiments of the inter-turn insulation testing device of the present invention. U, V, W...Terminal 1 of winding group - Impulse voltage generator 2...Waveform adjustment circuit 3...Winding 5...Waveform display 6...Switcher 8... waveform storage device
9...Waveform Comparator Agent Patent Attorney Inoue - Male Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) It has a plurality of winding groups of the same specification in which multiple turns of insulated wire rings are connected, each winding group has a terminal, and impulse A voltage generator, a wave-carving adjustment circuit that adjusts the voltage waveform generated by the impulse voltage generator, and a voltage generator connected to select and apply the impulse voltage to one of the terminals of each winding group; a switching device for grounding the terminal of the terminal and further switching between the impulse voltage application terminal and the grounding terminal, and a waveform storage device for determining the difference or sum of the waveforms of the applied voltage or the applied current due to the impulse voltage before and after switching by the switching device. , a waveform indicator that displays the difference or sum thereof, and a waveform comparator that displays or issues an alarm when the difference or sum exceeds a predetermined reference value. Test equipment 0 (2) The inter-turn insulation testing device according to claim 1, wherein the impulse voltages before and after switching have the same magnitude and polarity, and the waveform storage device calculates the difference in waveforms. (3) The inter-turn insulation testing device according to claim 1, wherein the impulse voltages before and after switching have the same magnitude and are reversible, and the waveform storage device calculates the sum of the waveforms.