SU1257582A1 - Method of determining location of faulted insulation of electric line - Google Patents

Abstract

The invention relates to electrical engineering and, in particular, to a technique for determining the location of damage (MP) in cable lines. The purpose of the invention is the extension of functionality due to the measurement of the parameters of symmetrical and asymmetrical lines. The essence of the method is as follows. Two wires make up a loop. The wires at the beginning of the loop are connected to the first poles of the two resistors. The second poles are connected to the first pole of the power source. The voltage between the wires at the beginning of the loop and the current at the end of the loop are measured. Moreover, the ratio of the resistances of both resistors is equal to the ratio of the resistances of both wires of the loop from the beginning of the line to the point of damage, the circuit illustrating this method contains a power source 1, a key 2, a voltmeter 6, an ammeter 11, a current-limiting resistor 3, additional resistors 4,5, transition resistors 12,13, wire - Earth. In MP, wires 7, 8, 9, SL С

Description

The invention relates to an electrical measuring technique, in particular a technique for determining the location of a convoy in cable lines.

The purpose of the invention is to expand the functional capabilities by measuring the parameters of symmetric and asymmetric lines.

Figure 1 shows the scheme is measured. A research institute illustrating the proposed method; in FIG. 2, the equivalent (transformed) measurement scheme.

The power source 1 (FIG. 1) through a switch 2, a current limiting resistor 3 (RO), auxiliary resistors 4.5 (Cdd and Rqi,) is connected to a voltmeter 6 and an aperture 7.8. Wire resistance

7.8 (R

 "Q

R j,). Are

the resistances of wires a and b from the beginning of the line to the location of the breaker (Wl) At the opposite end of the line to the wires 9.10 of the line with resistances RUQ, Ryf, respectively, ammeter 11 is connected. 13 wire-ground in GM wire rnb)

(Rh.

DOV 7-10,

Fiddles 14-19 (Fig. 2) indicate the resistances of the R, Rj, R, R, j, R, j, and Rg rays of stars, obtained by converting the resistance triangles in order to derive the crush equation.

To transform the triangles of fig „1,, 5 R ,, and E„ „, R, + R

 P6

Rya Rua + Rys- R, - R

D

Dv v

+ R

tf xR ,, / 1); R r

-I- P. meter 6,

with tid yjMi, / 15 1 de IN, -

R ,, / C; R RAO-RAB / C; c R

R R i7oi Rijo / D; R5. KHBK

A

noi

R, / D; D R

na

Ha

ij ,,.; resistance voltpv- in stars, we come to the equivalent circuit in Fig.25 where R, R ,.

We denote R. R, -n „+ R ,;

R

R, 1 „-

K.8- R5i

1 - battery current, Ig

currents respectively in branch x

R ,.

then

-about

 Rg

and I I

-oR, + R,

(one)

voltage on a voltmeter between points k and b

Uv- U, h (laR.)

(RT RS RgR.).

(2)

potential difference between points tp and p

and,., t; (R, R ,,) - I, (R, + R ,,)

 gs; k: ch b) -k8s .. a)

f 8

(3)

ammeter current

about

Ryo

- ()

ten

 X8 - R, + ha)

(four)

Looking in relation to (2) to (4), we obtain the resistance of the transfer of the loop (loop)

Uv

one

R

PP

 --S.i-Rj :.

RT (), T

(five)

from where

py

-

1+

R, -R. - R „.R,

(6)

In asymmetric lines R.Fvo.

LS (l about

Accept then

Bid „/ -, -. R n -J-j /; X8 DE

R,,.

g-- KC- (8)

Taking into account the conditions (/) and (8), R, K R and R К R substitute in (6)

will get

Ha

l &

2

Py

R

Jf2 ..

1 + Kg

(9)

from where

40 Rn.

py

R.,

; l1

(ten)

40

On the other hand, considering that

  4a Cha and R as shown in FIG. 1 through the resistance of the loop

five

RU RXO + RXB + R and R,

 Wah

 5 ammeters

a

Rip 4a + r

xs y (R

+ Rfl) - (R

,,. - V- ,, -d - - From (10) and (11) we get

Ije RQ -Rm

 R, -

Rj

..5- (R,. + RJ - R,

( one),

B

nulRg w

where do we come to the equation of measurement method

55

t, doo. 17 i

l (R / L) (K „T 1) (R ,, / R2)

where RXO is the resistance of wire b from the measuring point to MP.

Thus, the proposed method can be used to determine M in asymmetrical lines: coaxial pairs, in a loop from the core and sheath of the cable, in a loop from the cores of different layers of multi-core cable, etc.

In a homogeneous asymmetric line

R

Rx,

one)

ya +

 B

1.8

Rup XK + 1)

Rje) + (13)

respectively, the length of the line and the distance to the MP, the linear resistance of the wire b.

their

13) and (14), we get races

(12) instead of R and

1) - 1 + 5d / Gu ;; Rdsch / G9. / t,

15)

(Kpsh / Kg) + K.-1

As can be seen from (12), the method can be applied on non-uniform lines, but under the condition that the ratio R ' / Rde must be equal to the ratio of the resistances of the RC, / RB wires at least to the point of damage. From (15) it follows that in the case of a uniform line, the resistance of the plume Ry is not included in the formula.

To reduce the measurement error due to the error of the resistance

ten

15

20

of the additional resistors and the presence of wire asymmetry in the measured cable, the resistance of the additional resistors should be as large as possible, however, in this case, with a high value of the transient resistance R-„, the voltmeter reads in MP

By

Ammeters are reduced, which involves the use of highly sensitive instruments.

Claims (1)

Invention Formula The method of determining the fault location of an electrical line, in which two wires make up a loop, connect the wires at the beginning of the loop to the first poles of two resistors, the second poles of which are connected to the first pole of the power source, the second pole is grounded, measure between the wires at the beginning of the loop and the current - at the end of the loop, characterized in that, in order to extend the functionality by measuring the parameters of asymmetric lines, the ratio of the resistances of both resistors is chosen to be Resistance of the resistance of both wires of the loop from the beginning of the loop to the place of damage or to the place after the damage. t Editor M.Kelemes Compiled by N. Daki Tehred L. Oleinik Order 4914/44. Circulation 728 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 Proofreader M. Demchik