JPS5983067A - Diagnosis of insulation of electric machinery - Google Patents

Abstract

PURPOSE:To enable the judgement of an insulating state from a formula K=COI/COX-1 and a ratio RW/RD, by calculating the ratio of the initial value of electrostatic capacity under discharge start voltage or less and the value after deterioration and the ratio of DC insulating resistance in a dry state after deterioration and DC insulating resistance in a hygroscopic state after deterioration. CONSTITUTION:When the initial value of electrostatic capacity in AC voltage under discharge start voltage or less is set to COI and the value after deterioration of electrostatic capacity in the AC voltage is set to COX while DC insulating resistance in a dry state after deterioration is set to RD and DC insulating resistance in a hygroscopic state after deterioration is set to RW, an insulating state is judged from K and RW/RD. Void forming coefficient K% obtained from the initial value COI of electrostatic capacity Co under discharge start voltage or less and the value COX after deterioration and the ratio RW/RD of DC insulating resistance in the hygroscopic state to that in the dry state correspond to the non-destructive insulation characteristic value due to a conventional high voltage application method and it is found that this method is effective as an insulaion diagnosis method. As a result, measurement can be performed under low voltage and the capacity of a power source can be reduced as well as measurement can be carried out by a small apparatus.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] What is the invention? This invention relates to an insulation diagnosis method for electrical equipment such as lt machines and electric motors.

[Technical background of the invention and important points]

Insulating layer W of electrical equipment [destruction LJ as a method! These include tests, withstand voltage tests, non-destructive insulation property tests, physical and chemical tests, visual inspections, and operation history investigations. Insulation diagnosis using non-destructive insulation property tests has been most commonly performed in the past. Among these methods, the method of applying a direct voltage applies a relatively high voltage to reduce the voids, since the void content of the insulating layer is closely related to the dielectric breakdown voltage (HDV). Insulation diagnosis is performed based on changes in electrical strength.

However, due to such high voltage application! ! ! In the edge diagnosis method, if the maximum test voltage is lowered, sufficient void discharge will not occur.
There is a risk of EJ, which will make the deterioration level inaccurate, and, on the other hand, if the maximum test magnetic pressure is increased, there is a risk of insulation damage.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned problem, and an object of the present invention is to provide a method for diagnosing the insulation of electrical equipment that does not cause damage to the insulation of the equipment.

[Summary of the invention]

In order to achieve the above object, in the insulating layer 1Ilr method of the electrical equipment of the present invention, the initial value of the capacitor at an AC voltage below the discharge start 'Qj pressure is set to C6X, and the capacitance at the above-mentioned positive flow pressure is set to Cox is the value after the deterioration of the position, and [an example of the ability of the invention] Various canter edge deterioration diagnosis IUi data! - As a result of considering the two characteristic values obtained by applying heavy pressure Ichikawa, 1-
In other words, it is obtained from the initial value C61 of the alcohol volume %i'Co below the starting pressure of the fallen mountain and the value C8X after deterioration (COI
/COX 1) (T expressed as void generation coefficient and n-3i), and the ratio of DC insulation resistance during drying to moisture absorption itw/[L or conventional high tonne pressure It has been found that this method corresponds to the non-destructive insulation characteristic value obtained by the application method and has a correlation with the breakdown voltage of 4411, making it effective as an insulation diagnostic method.

This will be explained below using actual measurement data.

Figures 1 and 2 show the temporal change characteristics of K and RIw/lRo when a motorlet with epoxy mica insulation for V AC motors was aged at 200°C, 220°C, and 250°C. -1-.

Also a generator or AC~',! I! γ (γ divided by specific dielectric weight is equal to the void content of the insulating layer and has a high correlation with dielectric strength) and K measured using a new AC test method that has been proven in insulation diagnosis of II machines. and nw7 R, rl(7
) relationships are shown in FIGS. 3 and 4. Here, r1□ is 1
, 5 E (IG: rated voltage).

Further, FIGS. 5 and 6 show the relationship between the percentage of the dielectric breakdown voltage VB that is less than or equal to the initial value vBo, and K and [%w/[Lrl]. Figures 5 and 6 also show the results of heat deterioration of a sample made of an aluminum plate with the same insulation as the motoret.

From the results of [Ko] et al., K and Itw/R, are not only closely related to the insulation properties and breakdown voltage required by conventional high pressure application, but also that there is a risk of insulation damage due to excessive pressure application. Therefore, it can be said to be suitable as an insulation diagnosis method.

An example of how to perform insulation diagnosis using K and ULW/disconnection is as follows. K is determined by measuring +17'% capacity C3Q) at AC I KV (possibly even 500 V, but always measured? the pressure must be the same). The measurement is performed in a dry atmosphere at room temperature and humidity of 80% or less.

``'w/fun'' is the insulation resistance at 500 V DC (47, depending on the case, even 1 V or 'oJ, but unless the measured voltage is always the same, it is 7 [not possible)] in a dry state at room temperature.
Ft, o), and after 100% RH2E+ leaving (Rw)
Obtain by measuring. 1ull of insulation resistance 7. As the C resistor, a super insulating resistor ff1- (for example, 4Affγ1 Refurbished Packard Co., Ltd. J4329A) is used.

When measuring K and 1%w/It, D (7), if the tester is significantly contaminated, the values of capacitance and insulation resistance will be affected, so it is preferable to measure after washing and drying.

An example of the determination is shown in FIG.

It is preferable to carry out measurements as frequently as possible, but at least the following is desirable.

Good area: 1 time/year Shipment requiring attention 2 times/year Area requiring repair: 3 times/year Important new area 3 times/year [Effect of invention] Above ('+)1. As explained above, the “electricity 1” according to the present invention
) The single insulating layer 11J + force termination does not require applying FIJ as in the conventional method, and there is no fear of insulation damage due to the low voltage. , also;1.
Since the h river (1-; l1lI can be determined, the capacity I of the power supply
riLr 2] has the characteristics of small amount, delicious taste, and small packaging (can be measured with a hood).

[Brief explanation of the drawings] Figure 1 shows 1st floor of 1gu no Beni, j-hen 1hi - (' 1ill
h: Figure 1, Figure 2 is a curve diagram showing the change over time of Hashi/['Ll, Figure 3 is a diagram showing the relationship between γ15B and 1g, and Figure 4 is the relationship between γ1,6 and %71o. Figure 5 shows the relationship between K and IQ iit wave';'U'Iji pressure, Figure 6
The figure is il,! E and I'Lw / H・b 0) 1s
lj l system +:':l, seventh factor is a T relationship diagram showing an example of the criterion V when implementing the present invention. In these figures, rl, 5E is the constant of (relative permittivity) x (void content) +?
5 voltage at 15 times, vBo is the initial breakdown voltage, VB is the breakdown voltage after deterioration, F is the 111 current insulation resistance when moisture is absorbed, and O is when dry.
) represents countercurrent insulation resistance. (7317) Agent Patent Attorney Noriyuki Chika (Idiot 1)
Figure 1 Figure 2 Figure 3 Figure 4'/, EE (%J Electric\ Figure 7 k(a/,) Figure 5 (l)

Claims (1)

[Claims] 1. The initial capacitance at a current voltage of −F below the discharge start torque (uK is C61, the value after deterioration of the capacitance at the above y current voltage is Cox, and the value in a dry state after deterioration is 1. A method for diagnosing insulation of an electrical device according to item 1 of the scope of claim 1, characterized in that the surface condition of the electrical device is determined by plotting on the insulation coordinates of the electrical device.