RU2521163C1 - Protection circuit for induction electricity meters - Google Patents

Abstract

FIELD: electricity.SUBSTANCE: device contains a rotary aluminium disc with rotation axis with W-shaped electromagnet installed at its one side with a voltage coil connected in parallel to the mains input, and the opposed U-shaped electromagnet installed at the other side with a current coil coupled to the mains phase circuit in series to the load, as well as a register of the electricity meter coupled to the rotation axis. At that at the U-shaped electromagnet there is an additional current winding, both current windings are coupled to input phase conductor at the mains input through two high-voltage high-power diodes related to the phase conductor by different polarities while the other ends of current windings are interconnected thus forming an output phase conductor coupled to the load. Two circuits of parallel electrolytic capacitors and low-voltage diodes suppressing extra currents excited by the transformer in current windings are coupled to both current windings separately. Polarities of these low-voltage diodes, electrolytic capacitors and high-voltage high-power diodes match each other for each of the two phase circuits; and current windings are coupled so that they generate in the U-shaped magnet core a magnetic field with frequency of the mains.EFFECT: provision of protection for induction electricity meters from incorrect registration when high-frequency interruptions of operating current occur in active loads capable of such interruptions.1 dwg

Description

The invention relates to the field of electrical engineering and instrumentation and can be used to protect induction electric meters from the action of high-frequency interruptions of the operating load current.

It is known that when the operating current of an active load, for example, heating appliances, is interrupted at an increased frequency compared to the mains frequency in the range of 1 ... 5 kHz, induction-type electricity meters, which are widely used in the country, significantly underestimate the readings of consumed electricity (up to 75% ), which causes significant damage to energy supplying organizations, leads to an increase in electricity tariffs.

The aim of the invention is to provide effective protection of induction electric meters from incorrect metering of electricity under the action of high-frequency interruptions of the operating current in active loads that allow such interruptions.

This goal is achieved in the protection circuit of induction electric meters containing a rotating aluminum disk with a rotation axis, on one side of which a W-shaped electromagnet with a voltage coil connected parallel to the input of the network is installed, and on the other, an opposed U-shaped electromagnet with a current coil included in phase network circuit in series with the load, and also containing a counting mechanism associated with the axis of rotation of the metering of consumed electricity, characterized in that on a U-shaped electromagnet an additional current winding is placed, both current windings are connected to the input phase conductor of the network input through two high-voltage power diodes connected to the phase conductor of the network input with different polarities, and the other ends of the current windings are connected to each other and form an output phase conductor connected with the load, and Both current windings are connected separately two circuits of parallel-connected electrolytic capacitors and low-voltage diodes, damping extracurrents, transformer-excited in their current rpm patches, while the polarities of these low-voltage diodes, electrolytic capacitors and high-voltage power diodes are the same for each of the two phase circuits; and the current windings are turned on so that they form an alternating magnetic field with a network frequency in the U-shaped magnetic circuit.

Achieving this goal is explained by shunting the current windings with electrolytic capacitors in accordance with the polarity of the pulsating current flowing in these current windings, the interruption of which in the load is neutralized by the currents of these capacitors with a sufficient value of their capacitance during pauses (interruptions) of the current in the load, so that in a U-shaped the magnetic circuit arises an almost sinusoidal magnetic field that does not violate the correct accounting of the consumed electricity. The errors are also reduced by low-voltage diodes absorbing extracurrents, transformer-excited in non-working after half a period current windings from those working in this time interval.

The diagram is clear from the presented drawing, which contains the following nodes:

1 - aluminum disk in which eddy currents are excited,

2 - axis of rotation of the disk 1,

3 - counting mechanism with a digital display for reading energy consumption (kW · h),

4 - W-shaped magnetic circuit,

5 - voltage coil connected in parallel to the input of the network,

6 - U-shaped magnetic circuit,

7 - the first current winding,

8 - the second current winding,

9 - magnet braking aluminum disk 1 (soothing),

10 - protection module (a separate board built into the meter),

11 - the first high-voltage power diode (for example, for a current of 50 A with a reverse voltage of at least 400 V),

12 - the first electrolytic capacitor,

13 - the first low-voltage diode,

14 - the second high-voltage power diode (50 A, ≥400 V),

15 is a second electrolytic capacitor,

16 - second low voltage diode.

The arrows indicate the output from the meter to the loads. The input meter is connected to the 0.4 kV overhead line by a single-phase circuit.

Consider the action of the protection circuit of induction electric meters with high-frequency interruption of the load current at frequencies of 1 ... 5 kHz, which is used by attackers for theft of electricity.

In case of interruption of the load current by meander pulses with a duty cycle equal to two, which is typical for most schemes for rewinding the readings of induction electric meters, the pause time of the load current is 0.1 ... 0.5 ms (for the range of interruption frequencies 1 ... 5 kHz). In these pauses, the charge accumulated in the corresponding electrolytic capacitors 12 and 15 during the action of current pulses flows through the corresponding current windings, almost completely eliminating the current interruptions in these current windings, if the time constant of the LC circuit, where L is the inductance of the current winding, C - the capacity of the electrolytic capacitor is significantly longer (2 ... 3 times) the duration of the pause between current pulses. In other words, when (LC) ² ≈ 1 ms is selected, the shape of the half-wave current in the corresponding current windings will become almost the same as in the absence of current interruptions, which will ensure a practically sinusoidal change in the magnetic field in the U-shaped magnetic circuit 6. This ensures correct metering of electricity .

Replacing a U-shaped magnetic circuit with two current windings and incorporating a protection module 10 into the case of electric meters will significantly reduce the cost of re-equipment of typical induction electric meters, which are widely used due to their simplicity and reliability of operation.

The simplest modification of the claimed device is a parallel connection to a single current winding of the capacitor of the required capacity without any redoing the design of the meter. To do this, it is enough to use two low-voltage series-connected polar capacitors with the opposite inclusion of their polarities with doubled capacitance of each of them. The effect will be similar to the above.

Claims (1)

The protection scheme of induction electric meters containing a rotating aluminum disk with an axis of rotation, on one side of which there is a W-shaped electromagnet with a voltage coil connected parallel to the input of the network, and on the other, an opposed U-shaped electromagnet with a current coil connected in series in the phase network circuit with a load, as well as a counting mechanism for consuming electrical energy associated with the axis of rotation, characterized in that the additional currents are placed on the U-shaped electromagnet winding, both current windings are connected to the input phase conductor of the network input through two high voltage power diodes connected to the phase conductor of the network input with different polarities, and the other ends of the current windings are connected to each other and form the output phase conductor connected to the load, and to both current separately connected to the windings are two circuits of parallel-connected electrolytic capacitors and low-voltage diodes that quench the extracurrents transformer-excited in their current windings, with x low voltage diodes, electrolytic capacitors and high voltage power diodes are identical for each of the two phase circuits; and the current windings are turned on so that they form an alternating magnetic field with a network frequency in the U-shaped magnetic circuit.