SU1636794A1 - Method for measuring capacitor insulation impedance - Google Patents

Abstract

This invention relates to a measurement technique and can be used to measure the insulation resistance of capacitors. The purpose of the invention is to simplify and shorten the measurement time. The method for measuring the insulation resistance of capacitors involves charging the capacitor to the value of the measuring voltage and subsequent self-discharge for a predetermined period of time. Introduction of the capacitor billing process after the self-discharge time from the controlled source of compensating voltage Uk (t) nUo - (1 + n) (Do - Uc (t)), where n is a constant positive coefficient; Uo is the measuring voltage; Uc (t) is the instantaneous value of the voltage on the capacitor during the charging process to the value of the measuring voltage, through an exemplary resistor and further determination of the resistance r, R0 tl insulation from the Reese ratio, where P t2 ti is the self-discharge time of the capacitor; t2 is the dispensing time of the capacitor; The RO is the magnitude of the reference resistor, which made it possible to shorten the resistance measurement time, eliminate the capacitor capacitance measurement operation, and implement a group measurement method. 1 il. (L

Description

The invention relates to the field of measurement technology and can be used in instruments for measuring the insulation resistance of capacitors.

The aim of the invention is to simplify and shorten the measurement time.

The drawing shows an equivalent circuit of the principle of the method for measuring the capacitance isopia resistance.

The circuit consists of measuring voltage source 1 (Do), measuring capacitor 2 (Cx /) with insulation resistance 3 (Rn3), two switches 4 and 5, reference resistor 6 (Ro), and source 7 of condensing voltage Uic (t ), consisting of voltage sources 8 (Uko) AU (t), where k is a coefficient.

The method is implemented as follows.

Initially, the capacitor 2 is charged to the voltage Uo by closing the key 4 and unlocking the key 5. Then the key 4 is opened (the key 5 remains open) for a period of time q, during which the self-discharge of the capacitor 2 occurs through its insulation resistance. At the end of the self-discharge time, the voltage on the capacitor 2 becomes equal to

 tj

Uc (ti) U0e T, (1)

where rx Rizx is the time constant of the measured capacitor.

O w

about

4J

Yu

After the time ti the key 5 closure-- 11,. t

The process of dispensing con-UK ° y0 (i e k) + is carried out and carried out. eh 2

capacitor 2 through the exemplary resistor fi.m m At the same time, a current begins to flow through the circuit, it. - -t2 - - c.

equal to 5 1st 2 ° Uo (1-e g) +;

f and m "-II

.-c .--. 0- (1st) Uo (1-e).

- a - is (about + and. - to d u (Q Uh, - (1 - d d ism m m

jЈ- pr -i /, we denote

10-ta--

Equal to the right side of expressions (2). n; - A (1-e) 1st Tx.

and (3), we obtain the differential equation-Uo m

the first generation of dcap - ti -

 with - - 1 we have e e Gh

dAUffl Uo (1-k) AU (t) 15 m m

x 3t Ro RO from here t2 Y. Consequently, tz

from here 1

.dAU (t) (1-k) AU (t)

dt Q Ro Cx Ro since r0 0; rx 0; ti 0, then m 0,

Denote by r0 CxRo, 1 - k m.2 {i then

Get i

dAU (t) mAUft) Uko M)

at r0 r0 or

The solution of the differential equation of RO is neither the following: r2 ris - ti.

lod ..-..-.

- - e- tg: ha

-JUt- T2 °

+ C 30, (7)

, g -i p Y0V Uko. Go p 0g, rc Uk (t) nU0 - (1 + nXU0 - Uc (t)). (eight)

 -1 e t me From the expression f6) it can be seen that

- - t е

to m From expression (6) it can be seen that the measured value of impedance (f Uko e r0 4-С) measured by an Јn ni | (5) 35 years the isolation of the capacitor is independent of

Its capacitance and, therefore, the capacitance measurement operation is not required.

For the moment of time (the moment of the beginning, the device ensures the direct process of the charge of the capacitor) t 0, a barely measured insulation resistance in

Reasonably 40 gauge device and has the following

- the main technical characteristics: fromAU (ti) Uo - Uc (ti) Uo (1-e), measuring voltages 10 and 100 V, range .., h Uko + szon measured values RM3 Yu9 - TX) ohm,

 1 m charging time (at Cx 100 µF) not more than

Equate both expressions and find- 453 s, self-discharge time (ti) 0.1; one; ten; 100 and

dem S1000ch.

This method provides an opportunity U0 (1 - e rk) + -On implementation of the group method of measurement, allowing time spent on

Consequently, the expression (5) accepts the measurement of one capacitor to reduce

This is proportional to the number of capacitors, odC. - -constantly being in self-modeAu (t) o + Uo () + p yes.

l

Claims (1)

. Uko G. Formula 55 m je The method of measuring the resistance from iV of the time t2 / Uc (t2) Uo, then the capacitors, including charging AU (t2), 0 therefore, the capacitor to the value of the measuring tensions and subsequent self dh his / for a given period of time characterized in that, in order to simplify and shorten the measurement time, after the self-discharge time has elapsed, the capacitor is discharged from a controlled source of compensating voltage Uk (t) nUo- (1 + n) (Uo-Uc (t)), where n is a constant positive coefficient; Uo is the measuring voltage; 0 Uc (t) is the magnitude of the instantaneous value of the voltage on the capacitor in the process of deaeration, up to the value of the measuring voltage through an exemplary resistor, the charging time is measured, after which the insulation resistance of the RIZ of the capacitor is determined from RO. ti of P t2 where Ro is the value of the reference resistor; ti is the time of self-discharge of the capacitor; t2 - capacitor dispensing time.