SU1465776A1 - Method and apparatus for monitoring faults in power consumption in double-wire a.c. networks - Google Patents

Abstract

The invention relates to the field of electrical measurements and can be used to detect the disturbance of power consumption in two-wire AC lines. The purpose of the invention is to expand the range of control, sensitivity and noise immunity. This is achieved by measuring the intensity of the magnetic or electric field of a line and by exceeding by a intensity a value equal to the total level of the intensity of the field of symmetrical currents of normal consumption, ground currents and in other conductive structures located on the line path, signal a violation. The device for implementing the method contains sensors 1 and 2 of magnetic and electric fields, switch 3, band-pass filter 4, amplifier 5 and threshold indicator 6. 2 cf 1 hp 1 il. (L

Description

The invention relates to electrical measurements and can be used to detect violations of electricity consumption in two-wire $ AC lines.

The purpose of the invention is the expansion of the control range, increasing sensitivity and noise immunity.

The drawing shows the structure-jq io-functional diagram of a device that implements a method for monitoring violations of electricity consumption in two-wire alternating current lines. In these cases, the resulting field is determined by the difference in the magnetic fields of the symmetrical currents of normal consumption 1 _{from the} subscriber and can be written as

Н = Is fl - JL> ^ps 2 ϊΓ η К + <Р '(3) о

In addition, the magnetic field sensor 1 is affected by the equivalent current in the earth and in the conductive structures i _o , which is recorded as large in magnesium.

The essence of the method lies in the fact that they measure the strength of the filament or electric field, and when the strength exceeds the rank equal to the total level of the field strength of symmetrical currents of normal consumption, currents in the ground and in other conductive structures located on the line, they signal a violation

The device contains sensors 1 and 2 of the magnetic and electric fields and series-connected switch 3, a band-pass filter 4, an amplifier 5 and a threshold indicator 6, a two-wire line 7 and an equivalent drive 8. current, and the outputs of the sensors 1 and 2 of the magnetic and electric fields are connected to the first and second inputs of the switch 3.

The method of controlling violations of electricity consumption in two-wire AC lines is as follows. 40

In the measurements, the magnetic field sensor 1 is located in the magnetic field of the monitored current at a distance h from the two-wire line 7, the wires of which are spaced ₄ d apart from each other. At a distance of _{0 0} from the two-wire line 7, a wire 8 is located with an equivalent current in the ground and in other conductive structures placed on the line route. In the normal mode (in the absence of violations of the control of electricity consumption), the currents of the two wires of the line are equal (symmetrical) with each other and the equality i is satisfied,

those.

+ 12 “0, (ι) = -i ₂ = t _c (2)

2TG ϊξ + h *

The threshold indicator 6 does not work from the effects of the magnetic field of the indicated currents (I _c , 1 ₀ ), since its response threshold is detuned from the total values of the magnetic field strengths N _ps and Η _σο .

If the metering of electricity consumption is violated, equality (1) is not satisfied. At the same time, the magnetic field of the current of unaccounted-for ele energy is recorded as

S 2fii?

If we assume that ΐ _у = 1о = 1 _s , then the total interference coefficient of the magnetic fields of symmetrical currents of normal consumption (1 _C ), currents in the ground and in other conductive structures located on the line route (1 ₀ ) is written

(6)

Apparatus reliably rebuilt from the effects of magnetic gyeley symmetrical currents normal consumption currents in the ground and other conductive structures arranged on a line track, if the threshold indicator 6 is activated at a field strength in the sensor of magnetic current greater than or equal and - l lyaot ^H V ⁷ ' TTh ”---- ° ' ⁰⁸⁹¹ Nmax (7) s 1465776 4 where K _n is the detuning reliability coefficient, taken equal to 1.6;

^{Pm = K} 'c = 0,07 - total Pomeranchuk coefficient ^s hee magnetic fields symmetrical currents normal consumption currents in the ground and in other grovodyaschih konst- ruktsiyah iq when the sensor arrangement of the magnetic field at the optimum distance _HSV h = 0.2 m from a two-wire line 7 of the subscriber; u ~ the maximum load current of an individual subscriber in a given area.

The output signal of the magnetic field sensor 1 is supplied through the switch 3 ^ θ bandpass filter 4, amplifier 5 to the input of threshold indicator 6. If there is no violation of the metering of electricity consumption, then the currents of two-wire line 7 are directed in opposite directions, therefore, the value of the total value their electric field through the amplifier 5 is fed to the threshold indicator 6. Turn off the circuit breakers installed after the counter, and the sensor 2 of the electric field is looking for a hidden line, laid in addition to the electric tchika.

Claims (3)

SUMMARY OF THE INVENTION 1. A method for monitoring a violation of electricity consumption in two-wire AC lines, which consists in comparing two electrical signals and, in case the value of the first one is higher than the second, a signal is generated to fix the violation, characterized in that, in order to expand the control range , measure the strength of the magnetic or electric field of the line, convert it into an electrical signal and use it as the first compared electrical signal, and as the second electric signal is proportional to the total magnetic field strength is small and the symmetry current field norn is not sufficient for the threshold indicator 6. The threshold indicator 6 does not work also from the equivalent magnetic field of the currents of the grounding systems and conductive structures, since at the location of the sensor the value of there is little magnetic field. If the metering of electricity consumption is violated, then the subscriber’s current flows through one wire of the two-wire line 7 and the magnetic field of the line current at the location of the magnetic field sensor 1 increases by more than 10 times ₄₀ compared to the normal mode. In this case, the threshold indicator 6 is triggered and indicates, ₄ g that the metering of consumption of electrical consumption, currents in the ground and in other conductive structures located on the line route has been violated. 2. The method of pop. ^ characterized in that, in order to increase the sensitivity and noise immunity, the magnetic field sensor is placed at a distance of 0.15-0.25 m from the monitored line, and as a second electrical signal, a signal proportional to the magnetic field strength is set to greater than or equal to 0.089 1 _{Nmv (kS} , where 1 _{Nm (HKS) is the} maximum value of the load current. 3. Device for monitoring violations of electricity consumption in two-wire: alternating current lines, containing sequentially co-energy. Often the violation of electricity consumption is carried out in the form of secret sockets, laid in addition to the meter with a hidden line. To find such outlets with switch 3, the output of the electric field sensor 2 is connected to the input of the filter 4 and the output signal of the sensor 2 is a remote bandpass filter, amplifier and threshold indicator, which requires that, in order to expand the control range, introduced magnetic and electric field sensors and a switch, the output of which is connected to the input of the bandpass filter, and the inputs to the sensors of magnetic and electric fields.