SU385228A1 - DIGITAL FIXING DEVICE FOR MEASURING ELECTRIC VALUES - Google Patents

Description

one

The invention relates to fixing devices for measuring electrical quantities during short circuits on power lines used to determine the distance to the fault.

Known fixing devices of similar purpose are known, containing a reference memory capacitor, an auxiliary capacitor converter and a switch, performing a discrete discharge of the storage capacitor, and a pulse counter counting the number of discharge cycles that are a function of the fixed value.

In this case, in order to obtain a linear dependence of the meter readings on the monitored value, the storage capacitor can be discharged through a nonlinear element, for example, a T1 transistor.

In order to increase accuracy and extend the measurement range, the instrument converter is proposed to provide a square pulse generator connected to the input circuits of the switch with an element to control the level of the measured value and two capacitors. One capacitor capacitor is connected in parallel to the input circuits of the converter, and the second is parallel to the auxiliary capacitor through the contact of the element of the control of the measured value level.

The drawing shows a schematic electrical diagram of the described device.

The digital fixing device contains a voltage transformer 1, the primary 5 winding of which is supplied with a controlled voltage, a rectifying bridge 2, a start and control relay 3, a start and control relay contacts 4-6, a pulse counter 7, a storage capacitor 8 with a capacitance C and an auxiliary capacitor 9 with capacitance C, relay element 10, contact of relay element //, potentiometer 12, additional capacitors 13, 14, capacitance Cz and C, respectively, transistors 15-17 (n-p-p type), generator of symmetric rectangular pulses 18 with out Dami a and b, the element of control of the level of the measured value 19 and the contact of the element of control 20.

The device works as follows. In the initial state, the capacitors 8, 13 are discharged, the transistor 17 is open, the transistors 15, 16 are closed. At the base of the transistor 15, the blocking potential is transmitted through the collector-emitter junction of the transistor 17.

five

When a short circuit on the line to the primary winding of the transformer / voltage is applied / 7f, and the starting relay 3 is triggered. The relay by its contact 4 connects the storage capacitor 8 to the charging circuit, and the contactor 6 starts the pulse generator.

In this case, the capacitor 8 is charged before the voltage Sf, where AI is the proportionality coefficient.

After 1 noncotary time, about 0.1 seconds after the start of a short circuit, relay 3 opens contact 4 and after a specified time closes contact 5 in the converter circuit. In this case, the voltage on the capacitor 8 decreases to the value:

L

U, UACi + Cs

The discrete cyclic discharge of capacitors 8, 13 is as follows.

When a pulse arrives from the output of the generator 18 to the base of the transistor / 7, the latter closes and removes the locking pulse from the transistor 15. The transistor 15 opens and the capacitor 9 is charged from the capacitors 8, 13 to the voltage But set by potentiometer Л2.

In this case, under the action of the charging current, transistor – relay 10 is activated, and with its contact (I) it turns on the pulse counter 7, which counts its first pulse.

After that, the output of generator 18 receives a pulse and the base of the transistor 16. The transistor opens and discharges the capacitor 9.

Upon receipt of the following pulses from generator 18, the P1 process repeats and the counter reads until the voltage on the capacitors 8.13 drops to U.C, at which the new charge current pulse of the capacitor 9 cannot trigger the relay 10.

The number of pulses K, counted by the counter, can be found from the equation:

U, V, -K. . , B and „+ and ,.

C, + Sz -fl

from where

and, - and, + and, with, + with, p + 1

TO

and.

with f / c f / ft

1 l 1l Cj + s, p - f 1

 TT-, where Ly.; -,

UQСз.Р

p is the current gain of transistor 15.

Since the number of pulses K is in

linear dependence of the noise on the value of U, then the pulse counter can be P1 rograded in volts.

In case the input signal sounds like

the magnitude of the response of the level control element 19, the latter is triggered and by its contact 20 connects parallel to the capacitor 9 a capacitor 14. Pr, and this increases the capacitance of the cyclic discharge capacitor to Cz + C, and the number of pulses is given by:

and n

Where:

 Ci + C P + 1

 k - f 1 / Q 62 +

As a pulse counter in the device, a pulse counter 1 can be used on asymmetric triggers with two-position relays, for example, of the RPS type, and indicator lamps of the IN-2 type. At the same time to reproduce information when the operational voltage disappears

The indicator lamps can be powered by pre-charged capacitors.

Pavedmet invented: and

A digital fixing device for measuring electrical magnitudes in case of a short circuit on a power line, containing a reference memory of a capacitor,

a converter in the form of an auxiliary capacitor, a nonlinear element and a switch, carrying out a discrete discharge of a storage capacitor, and a pulse counter, counting the number of cycles and scaled in units of measurable value, characterized in that, in order to extend the measurement range 1 and increase the accuracy, the converter is additionally equipped with a generator of rectangular pulses,

connected to the input circuits of the switch, a control element of the measured value level and two capacitors, one of which is connected in parallel to the input circuit of the converter, and the second parallel to the auxiliary capacitor through the contact of the control element of the measured value.

Dli

18 c,