RU2498322C1 - Electric meter with protective cutout - Google Patents

Abstract

FIELD: electricity.SUBSTANCE: electric meter with protective cutout containing current sensor which outputs are connected to current-by-voltage multiplier which in its turn is connected to current-to-pulse frequency converter, current transformer with two primary windings and one secondary winding at which the signal is proportional to current difference of primary windings and rectifier; at that outputs of the transformer through rectifier converting alternating-current signal into a direct-current signal are connected to current-to-pulse frequency converter; at that when a signal at the rectifier output exceeds a signal from current-by-voltage multiplier and it is fed to current-to-pulse frequency converter then this current-to-pulse frequency converter will ensure maximum frequency of pulses; it includes an auxiliary voltage peak protective relay which outputs are connected to phase and neutral conductor of the measuring circuit, primary windings of the transformer are connected to phase and neutral conductor of the measuring circuit through a normally closed contacts of the voltage peak protective relay.EFFECT: ensuring protection of electric meter from voltage surges or low voltage in the mains.1 dwg

Description

The invention relates to electrical engineering and is used to measure electrical energy in AC circuits with a view to its consideration.

A known electric energy meter containing a current sensor, the outputs of which are connected to a current multiplier for voltage, which, in turn, is connected to a current transducer in a pulse frequency, a current transformer with two primary windings, one of which is connected to a phase conductor of the measuring network, the other with a neutral conductor and one secondary winding, on which the signal is proportional to the difference of the currents of the primary windings, and a rectifier, while the transformer outputs through a rectifier that converts an alternating signal If the signal from the output of the rectifier, exceeding the signal from the output of the current multiplier to the voltage, is supplied to the current converter to the pulse frequency, then the current converter to the pulse frequency gives the maximum pulse frequency ( RF patent for the invention No. 2254582, class G01R 21/06, G01R 11/24, published on June 20, 2005).

A disadvantage of the known electric energy meter is the reduced functionality due to the lack of the ability to protect the meter from over or under voltage in the network. This disadvantage is especially evident in electronic meters of electrical energy.

The aim of the invention is to expand the functionality of the electric energy meter.

An object of the invention is to provide protection of the electric energy meter from over or under voltage in the network.

The technical result of the invention is achieved in that the electric energy meter with protective shutdown, containing a current sensor, the outputs of which are connected to a current multiplier by voltage, which, in turn, is connected to a current to pulse frequency converter, a current transformer with two primary windings and one secondary a winding on which the signal is proportional to the difference of the currents of the primary windings, and a rectifier, while the transformer outputs through a rectifier that converts the alternating signal into a constant signal a, they are connected to the current transducer in the pulse frequency, if the signal from the output of the rectifier, exceeding the signal from the output of the current multiplier to the voltage, is supplied to the current transducer in the pulse frequency, then the current transducer in the pulse frequency gives the maximum pulse frequency, additionally contains a protection relay from power surges, the inputs of which are connected to the phase and zero conductors of the measuring network, the primary windings of the current transformer are connected to the phase and zero conductors of the measuring network through rmalno closed contact relay surge.

The technical result of the invention is achieved through the use of an overvoltage protection relay in the electric energy meter, the inputs of which are connected to the phase and zero conductors of the measuring network and by the fact that the primary windings of the current transformer are connected to the phase and zero conductors of the measuring network through normally closed contacts of the protection relay from power surges.

The drawing shows a functional diagram of an electric energy meter with protective shutdown, where: 1 - current sensor; 2 - load; 3 - current multiplier for voltage; 4 - current to pulse frequency converter; 5 - current transformer with two primary windings and one secondary; 6 - rectifier; 7 - surge protection relay; L is the phase conductor; N is the neutral conductor.

The electric energy meter with protective shutdown contains a current sensor 1, the outputs of which are connected to a current multiplier 3 for voltage, which, in turn, is connected to a current / voltage pulse converter 4, a current transformer 5 with two primary windings, and one secondary winding, on which the signal is proportional to the difference of the currents of the primary windings, and the rectifier 6, while the outputs of the transformer 5 through the rectifier 6, which converts the alternating signal into a DC signal, are connected to the current converter 4 to the frequency and pulses, while if the signal from the output of the rectifier, exceeding the signal from the output of the current multiplier 3 to the voltage, is supplied to the current converter 4 to the pulse frequency, then the current converter 4 to the pulse frequency gives the maximum pulse frequency, and also contains a relay 7 of protection against voltage surges whose inputs are connected to the phase and neutral conductors of the measuring network, the primary windings of the current transformer 5 are connected to the phase and neutral conductors of the measuring network through normally closed contacts of the relay 7 in tension.

The electric energy meter with protective shutdown operates as follows.

The counter contains a current sensor 1, a current multiplier for voltage 3, a current to pulse frequency converter 4, a current transformer 5 with two primary windings and one secondary winding, on which the signal is proportional to the difference of the primary currents and rectifier 6, which converts the alternating signal into a constant signal current. When you try to steal electricity by grounding one of the outputs of load 2, the difference between the currents of the phase conductor L and the neutral conductor N becomes non-zero and the signal from the output of the rectifier 6, exceeding the signal from the output of the multiplier 3, is fed to the current converter in the pulse frequency 4. In turn the current to pulse frequency converter 4 gives the maximum pulse frequency, the counter begins to count faster than it should. Thus, the counter, the diagram of which is shown in the drawing, provides the possibility of preventing theft of electricity, as well as the punishment for attempting such theft.

During operation, if the voltage is outside the permissible limits, the load is automatically switched off. When voltage is restored to normal, the relay 7 surge protection is automatically turned on with a delay of 6 minutes or 10 seconds.

When the voltage in the network exceeds 270 V, the surge protection relay 7 disconnects the network with a delay of 0.2 s. With a voltage increase of more than 300 V, an accelerated shutdown of <20 ms occurs. In the event of a decrease in the voltage of the network below 170 V, the load is switched off with a delay of 10 s, and when the voltage drops below 130 V, an accelerated disconnection <100 ms occurs. In normal operation mode (relay on), when the “TEST” button is pressed, the surge protection relay 7 disconnects the load, which indicates the normal functioning of the device.

The “TEST” button of the manual control allows you to turn on the power to the load, without waiting for the end of the turn-on delay time, or turn it off if you want to disconnect consumers.

When powerful voltage pulses appear in the network, the built-in varistor shunts them to a value safe for the equipment.

Claims (1)

An electric energy meter with protective shutdown, comprising a current sensor, the outputs of which are connected to a current multiplier by voltage, which, in turn, is connected to a current to pulse frequency converter, a current transformer with two primary windings and one secondary winding, on which the signal is proportional to the difference primary currents, and a rectifier, while the transformer outputs through a rectifier that converts an alternating signal into a direct current signal, are connected to a current transducer in a pulse frequency c, if the signal from the output of the rectifier, exceeding the signal from the output of the current multiplier to the voltage, is supplied to the current transducer in the pulse frequency, then the current transducer in the pulse frequency produces the maximum pulse frequency, characterized in that it contains a surge protection relay, inputs which are connected to the phase and neutral conductors of the measuring network, the primary windings of the current transformer are connected to the phase and neutral conductors of the measuring network through normally closed contacts of the surge protection relay in voltage.