RU2348094C2 - DEVICE FOR CONTROL OF ZERO CONDUCTORS INTEGRITY IN LINES OF 0,38 kV - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: invention is related to the field of metering equipment and may be used for provision of electric and fire safety in process of electric installations operation by means of reliable disconnection of loads in case of single-phase damages of insulation. Invention is based on technical problem of providing control of zero conductors integrity. Specified problem is solved by the fact that device for control of zero conductors integrity in lines of 0.38 kV that comprises three-phase power transformer connected by phase wires with single-phase and three-phase loads, dead-earthed neutral of transformer is connected to zero protective and zero working conductors additionally comprises, according to invention, single-phase double-winding transformer, primary winding of which is connected into inset of zero working conductor and is connected by means of resistor and button with phase wire, and secondary winding of transformer is connected serially to reacting element that influences the signal element, and is connected into inset of zero protective conductor, outlet of which is connected to grounding device.

EFFECT: provision of zero conductors integrity control.

1 dwg

Description

The invention relates to the field of measuring equipment and can be used to ensure electrical and fire safety during operation of electrical installations by reliably shutting off consumers in case of single-phase insulation damage.

A device for monitoring the continuity of the neutral circuit of domestic installations, which simultaneously measures the resistance of the protective conductor and controls the continuity of the neutral grounding circuit of the supply transformer.

The device contains the following elements: r ₀ - neutral grounding resistance; r _W - shunt resistance: r _P - re-grounding; IB - measuring unit; IOT - source of operational current, NZP - zero protective conductor; БК - neutral grounding circuit control unit [1].

The disadvantages of the known device are: an increase in the resistance of the grounding line due to the inclusion of a shunt r _Ш in the cut-off of the NZP; deterioration in the quality of electricity in this network due to the imposition of a constant operating current; deterioration of the normal operation of the neutral grounding of the supply transformer due to the presence of a VD diode.

There is also a device for monitoring the continuity of the zero conductor in 0.4 kV overhead lines, containing measuring current sensors, an actuator, a computing unit, a symmetry checking unit and a decision unit, while one of the measuring sensors is connected by its input to the input signal source, which is the current in the neutral wire at the beginning of the line, and its output is connected to one of the inputs of the symmetry check unit and the input of the computing unit, the output of which is connected to one of the inputs of the decision unit, another measuring sensor is connected by its input to the input signal source, which is the current in the neutral ground of the transformer, and its output is connected to the second input of the symmetry check block and one of the inputs of the decision block, the output of the symmetry check block is connected to the third input of the decision block, output which is connected to the input of the actuator [2].

The disadvantage of the zero-conductor continuity control device in 0.4 kV overhead lines is that the lack of load does not allow to control the continuity of the ground circuit and voltage appears on the cases of electrical equipment with an unbalanced load connected to the 0.38 kV network.

The closest adopted as a prototype is a consumer power device via a five-wire 0.38 kV network, containing a three-phase power transformer connected by phase wires to single-phase and three-phase consumers, to reduce the touch voltage and connect a single-phase load, the transformer neutral earthed neutral is connected to zero protective and zero working conductors. Such a solution reduces the contact voltage on the electrical equipment housings when, under an asymmetric phase load, a load current flows in the neutral conductor [3].

A disadvantage of the known device is the lack of control of the continuity of the zero protective conductor. In case of violation of the continuity of the zero protective conductor, the sensitivity of the devices to damage to the phase insulation of electrical equipment deteriorates.

The basis of the invention is the technical task of ensuring continuity control of zero conductors.

This problem is solved by the fact that in the device for monitoring the continuity of the zero conductors in the 0.38 kV lines, containing a three-phase power transformer connected by phase wires to single-phase and three-phase consumers, the dead-grounded neutral of the transformer is connected to zero protective and zero working conductors, according to the invention, a single-phase double-winding a transformer, the primary winding of which is included in the cut of the zero working conductor and connected via a resistor and a button to the phase wire, the secondary winding of the transformer is connected in series with the reactant body, acting on a signal element, and included in the crosscuts protective conductor whose output is connected to the ground connection.

To clarify the described device, the drawing shows the diagram and organization of measurements.

The device contains a consumer transformer 1 with a grounded zero point 2, phase wires 3 provide power to consumers 5, a neutral working conductor 4 provides power to single-phase consumers 15 connected between conductors 4 and 3. All cases of electrical equipment 5 are connected to zero point 2 with a zero protective conductor 6. The following are introduced into the device: single-phase two-winding transformer 8, one winding 9 of which is included in the cut-off of the zero working conductor 4, and the second winding 10 is included in the cut-out protective conductor 6; a chain of sequentially connected buttons with a make contact 11 and a resistor 12 connected between the phase wire 3 and the neutral working conductor 4; the reacting organ 13 connected in series with the winding 10 of the transformer 8 into the cut-off of the neutral protective conductor 6 and connected to the ground electrode 7 through the housing of the electrical equipment 5. A signal element 14 is connected to the output of the reacting organ 13.

The device operates as follows.

In the symmetrical mode of operation of the network in the neutral conductor 4 and in the primary winding 9 of the transformer 8, no current flows. To ensure the flow of current in the zero working conductor 4, the contact of the button 11 is closed, the resistor 12 limits the amount of current flowing through the zero working conductor 4. Under the influence of this current, an EMF is induced in the secondary winding of the transformer 8, which ensures the flow of current along the circuit: the secondary winding 10 of the transformer 8, neutral protective conductor 6, reacting organ 13, electrical equipment housing 5, re-earthing switch 7, earth and grounding of neutral 2 of power transformer 1. Under the action of zero flow CB protective conductor current is triggered responsive element 13, whose output signal is fed serviceability neutral conductor 4, protective conductor 6 and the grounding devices 5 and 7, electrical grounding of the supply transformer 2 1.

In the event of a malfunction of any of the elements of the controlled circuit, the signal by element 14 is not supplied.

The use of the invented device will avoid the negative consequences of a break in the working and protective conductors by timely signaling of a malfunction.

Information sources

1. Pyastolov A.A., Sidorov A.I., Kataeva N.K. Monitoring the continuity of the grounding circuit of municipal installations // Technique in agriculture. - 1988. - No. 5. - S.60-61.

2. Description of the invention to the patent of the Russian Federation RU 2230415 C1, H02H 5/10, G01R 31/02.

3. Electricity quality management / I.I.Kartashev, V.N. Tulsky, R.G. Shamonov and others. Ed. Yu.V. Sharova. - M.: Publishing House MPEI, 2006. - 320 p.: Ill.

Claims (1)

A device for monitoring the continuity of neutral conductors in 0.38 kV lines, containing a three-phase power transformer connected by phase conductors to single-phase and three-phase consumers, a dead-grounded neutral of the transformer connected to zero protective and zero working conductors, characterized in that a single-phase two-winding transformer is introduced, the primary winding of which included in the cut of the zero working conductor and connected by means of a resistor and a button with a phase wire, and the secondary winding of the transformer with it is connected in series with the reacting body acting on the signal element, and is included in the cut of the zero protective conductor, the output of which is connected to the grounding device.