SK5538Y1 - Device for automatic continuity measuring of protective conductor PEN a PE - Google Patents

Abstract

The technical solution relates to device for automatic measuring the connection of the protective conductor (PEN) and (PE). Described technical solution consists of two devices. The first device (PENCE) is designed for automatic detection of connection of the protective conductor (PEN), namely from the source, i. e. from transformer to the distribution point (PEN) of the conductor by the measuring current transformer (MTP). Second additional device (ENCE) automatically detects connection of the protective conductor (PE) from the point of sharing the conductor (PEN) in distributor to the end appliance in the electrical installation, in network (TNC-S). The current use of the device (PENCE) and (ENCE) covers the control of the connection of the protective conductor from the power source, i. e. from the transformer to the appliance.

Description

The described technical solution consists of two devices. The first PENCE device is designed to automatically detect the continuity of the PEN protective conductor in the power distribution lines, which are dedicated electrical equipment from source t. j. from the transformer to the dividing point of the PEN conductor into a separate N conductor and a separate PE conductor in the switchgear in the TNC resp. TNC-S. The second additional ENCE device automatically detects the continuity of the PE protective conductor from the point of distribution of the PEN conductor in the switchgear to the end consumer in the electrical installations, TNC-S network, or the network. TNS, especially in socket circuits and in circuits of objects of the first (first) class. The simultaneous use of the PENCE and ENCE devices therefore covers the continuity check of the protective conductor from the power source t. j. from transformer to appliance. Note: Class I articles are electrical articles for which a protective terminal is prescribed and for which a protective conductor is used to protect against electric shock.

BACKGROUND OF THE INVENTION

At present, we are not aware of a device that would automatically measure the continuity of a PEN aPE protective conductor.

In accordance with IEC 60364-6: 2006 and the harmonization document HD 60364-6, the harmonized STN 33 2000-6 Part 6: Revision referred to in Art. 61.3.2 (joint modification with international standard) - Continuity of conductors - in paragraph (a) Continuity test shall be carried out on protective conductors including protective conductor conductors and supplementary conductor conductors. The inspection technician can verify the continuity of the PEN and PE protective conductor, e.g. by measuring the protective conductor impedance (resistance) with special conductor resistance meters, resp. which is technically demanding, sometimes impossible for long distances.

Inspections of electrical equipment are carried out when the equipment is put into operation (initial revision or initial expert inspection and expert examination) and repeatedly in the prescribed terms depending on the type of object in which the wiring is located and depending on external influences within 1/2 year up to 5 years. In the period before the required baseline revision eg. after installation, repair, reconstruction, modernization and between repeated revisions, the PEN or PE protective conductor may be interrupted and a dangerous condition in the electrical installation may occur. j. to the possibility of electric shock.

(There have been instances where electrical equipment has been destroyed when the protective conductor has been interrupted or, in the worst case, fatal injury).

The essence of the technical solution

The risk of electric shock when the protective conductor is interrupted is increased because the electrical equipment may be capable of operating, but the most widespread protection against electric shock to inanimate parts - self-disconnection from the power supply is not effective.

These are mainly objects where electrical energy (wiring) is used by persons without electrotechnical qualifications, laymen, and thus there is an increased presumption of electric shock.

If the PEN or PE protective conductor is interrupted, there is no protection against electric shock by self-disconnection from the power supply, and the functions of supplementary protection against electric shock - residual current circuit breakers and overvoltage protections are also endangered.

The present technical solution of ENCE and PENCE devices see drawing no. 4 are devices containing electrical and electronic components contained in individual parts of the device. ENCE device see drawing no. 1 contains NZE power supply units, GIE pulse generator, MBE measuring blocks, RJE control unit and NPP S signaling unit, and in PENCE, see drawing no. 3, fuse block BI, rectifier U, power supply NZ, backup power supply A, measuring circuits MO, auxiliary circuits of POMTP current transformer, MTP current transformer, RJ control unit and SJ signaling unit The use of this technical solution is designed for automatic continuity detection protective conductor PEN (PENCE device) and PE (ENCE device) in TN-CS resp. TNS, in switchboards and electrical circuits located in the power distribution. Automatically detecting the continuity of the protective conductor in this case means that it is possible to set the time how often the continuity of the protective conductor should be checked (eg once per minute, hour, 24 hours, etc.) depending on the period of use of mainly Class I items.

The ENCE device consists of an NZE power supply unit including a back-up power supply - a battery (with autonomy as needed), a GIE pulse generator, two MBE1 and MBE2 measuring blocks, controlling

551 RJE unit containing mainly comparators and microprocessor and SJE signaling unit containing signaling elements. The essence of automatic PE continuity measurement consists in sending pulses according to STN EN 61557 (IEC 61557) through the protective conductor and the middle conductor and their identification from which direction the pulses return by means of current transformers and evaluation of these pulses by microprocessor placed in the control RJE unit. After the pulses are detected and the protective conductor status is evaluated by the microprocessor, the status of the protective conductor and protective connection is signaled by the green LED. In the event of an interruption of the protective connection but an uninterrupted protective conductor, the red LED will be permanently lit and a continuous, audible beep will sound to indicate an imminent dangerous condition and, in the case of an interrupted protective conductor the operator (user) of electrical equipment that work with electrical equipment, especially Class I, must not be continued.

The power supply of the ENCE in the three-wire system is single-phase, see drawing no. 1, the five-conductor system may be single-phase or three-phase, see drawing no. 2. Three-phase power supply increases the reliability of the power supply while checking the interruption of one of the phases.

The test button “TT” is a part of the RJE control unit and is used to start the continuity test of the protective conductor and protective bonding at any time, especially when starting to use Class I electrical objects, eg washing machines, etc. After the continuity test, the ENCE shows the user of the electrical object that the device is connected to a protective conductor and can be used safely.

We recommend ensuring the ENCE is protected against overvoltage with class D (IV) overvoltage protection.

We propose to use the ENCE device directly in the socket circuits (i.e. directly in the sockets) and in particular in the circuits of appliances (i.e. directly in the appliances) of I. (first) class objects, such as for example. washing machines, dishwashers, refrigerators, freezers, electric heaters, water heaters and irons in households, refrigerators, freezers in restaurant facilities, office computers, computers and engines in production plants.

The PENCE device includes: NZ power supply, which provides power to the control and auxiliary circuits and to charge the backup battery A. Battery A is continuously recharged during operation and provides power to the control and signaling unit in the event of a power failure or interruption. The autonomy of the power supply of the device given the battery capacity must be determined individually according to the type of operation where the device will be used. However, we recommend at least 6h. The power supply is designed as a galvanic isolated, its primary neutral point can be disconnected by a control signal from the control unit in order to increase safety in case of detected PEN wire interruption by means of an electronic high impedance switching circuit.

The method of evaluating the continuity of the PEN conductor is as follows: Phase voltages are rectified in the rectifier U in one way. Positive and negative half-waves are evaluated separately. The measuring resistance divider in the MO at voltage connection (via an electronic switching element) flows the measuring current (according to STN EN 61557, IEC 61557), which generates a voltage drop on the divider, smoothed by the capacitor. This voltage is compared with the reference value in the comparator and the evaluated logical output of this operation is processed by the control unit RJ.

The MTP current transformer must be dimensioned according to the parameters of the switchgear in which it is connected. In the secondary circuit in the POMTP, the measurement transformer, due to the need to evaluate relatively small currents, it is necessary to provide sufficient resolution of the evaluation circuit within the range of values and the current of the PEN continuity itself (under unloaded PEN wire). At the same time, the circuit must also bear the full load (from the load), while distinguishing the absolute value of the current is only necessary to the extent necessary to evaluate the measuring current. The MTP current transformer is used in the circuit for the purpose of determining the path of the closing of the measuring current from the power supply:

1. PEN conductors to the power supply,

2. to the local ground of the PEN of the driver;

3. PEN conductors,

For proper operation of the device, the MTP should be connected (from the point of view of the power supply - eg transformer) before the point of division and local grounding and connection of this device to the PEN wire.

The control unit RJ ensures connection of the measuring circuit at required intervals, evaluates the measuring current, its closing path and controls the signaling unit in case of PEN disconnection of the conductor and power failure. The control unit also includes a test button "TT", which is used to run the test of continuity of the protective conductor and protective bonding at any time.

The signaling unit S J signals the safe and fault states by sound and light signaling. In case of an uninterrupted PEN wire, the green LED lights up. If the PEN wire break is evaluated, the red LED flashes and a strong, intermittent intermittent beep sounds. In the event of a power failure, the red LED will light and a continuous beep will sound.

SK 5538

In this case, the automatic detection of PEN continuity means that it is possible to set how often the continuity of the protective conductor should be checked (eg once per minute, hour, 24 hours, etc.) depending on the duration of use of Class 1 items.

The PENCE device is intended for use in the TNC's low-voltage networks. TNC-S, where it is to perform the task of automatic operational continuous check of continuity of the PEN supply conductor.

There is an increased risk of electric shock in metal distribution and protection cabinets of the electricity distribution network, given the fact that they are placed in publicly accessible places and are accessible to non-electrically qualified persons, laymen. If the PEN protective conductor is interrupted, there is no protection against electric shock by disconnecting itself from the power supply after the PEN conductor interruption point, and phase voltages may be given to the inanimate parts of metal distribution and protection cabinets and class I appliances in the downstream wiring.

We recommend PENCE for use directly in switchgear in order to provide (visible and audible) signaling of the protective conductor status. The advantage of using the PENCE device in conjunction with the ENCE device is that it covers the continuity check of the protective conductor from the transformer source to the appliance. See drawing no. 4th

Another advantage of using two PENCE and ENCE devices is to divide the continuity measurement of the protective conductor into a part from the source to the split point and the part after the split point. Downstream of the distribution point, PE and N conductor are used for the measurement and thus the transformer is not loaded by the measuring pulses, which could cause problems with a large number of consumers.

Given the fact that the ENCE and PENCE devices contain electronic components, it has its own consumption (assuming up to 2W), which is a disadvantage. Another disadvantage is that it can be a source of higher harmonics, since in this design the device does not include a higher harmonics filter. If the ENCE and PENCE devices are used in larger quantities, we recommend to equip the device with a harmonic filter.

Overview of drawings

Drawing no. 1 - Block diagram of the ENCE device for automatic PE continuity measurement for a three-wire electrical installation.

Drawing no. 2 - Block diagram of the ENCE device for the automatic measurement of the PE conductor continuity for a five-wire electrical installation.

Drawing no. 3 - Block diagram of the PENCE device for automatic continuity measurement of the PEN protective conductor.

Drawing no. 4 - Example of connection of ENCE and PENCE devices for automatic continuity measuring of PEN and PE.

Example of technical solution.

Device for automatic continuity measurement of PE, ENCE see drawing no. 1, the device is composed of a power supply NZE including a backup power supply - an accumulator with autonomy as required e.g. 12 hours, pulse generator GIE, two measuring blocks MB1 and MB2 with current transformers, control unit RJE containing mainly comparators, control microprocessor and test button TT and from signaling unit SJE containing light signaling by green and red LED and sound signaling with penetrating sound signal.

The device is mounted directly into a class I (first) appliance. washing machines, dishwashers, computers, etc. where it will indicate the status of PE protective conductor after the dividing point, or directly to a socket supplying Class I appliances.

Protective wire continuity measurement consists of sending pulses from the GIE pulse generator through the protective conductor and the middle conductor, identifying them (from which direction the pulses return) using current transformers in the MBE1 and MBE2 measuring blocks and evaluating them via a microprocessor located in the RJE control unit. .

After evaluation of the pulses by the microprocessor, the status of the continuity of the protective conductor and the protective connection is signaled in the signaling unit SJE by the green LED. In the event of an interruption of the protective connection but an uninterrupted protective conductor, the red LED will be on permanently and a continuous, audible beep will sound to indicate an imminent dangerous condition and, in the case of an interrupted protective conductor. the operator (user) of electrical equipment, that electrical equipment must not be touched and that work with electrical equipment, in particular Class I, must not be continued.

SK 5538 Υ1

At the same time, a device for automatic continuity measurement of the protective conductor PEN, PENCE, which contains NZ power supply, which provides power supply for control and auxiliary circuits and charging of backup battery A, is mounted on the switchboard supply. Battery A is continuously recharged during operation and power failure or interruption The PEN driver provides power to the RJ control unit and the SJ signaling unit. The autonomy of the power supply of the device given the battery capacity must be determined individually according to the type of operation where the device will be used. However, we recommend at least 6h. The power supply NZ is designed as a galvanic isolated, its primary neutral point can be disconnected by a control signal from the control unit RJ to increase safety in case of detected PEN wire break by means of an electronic high impedance switching circuit.

The method of evaluating the continuity of the PEN conductor is as follows: Phase voltages are rectified in the rectifier U in one way. Positive and negative half-waves are evaluated separately. Measuring circuit MO1, MO2 at voltage connection (via electronic switching element) flows the measuring current (according to STN EN 61557, IEC 61557), which creates a voltage drop on the divider, smoothed by the capacitor. This voltage is compared with the reference value in the comparator and the evaluated logical output of this operation is processed by the control unit RJ,

The MTP current transformer must be dimensioned according to the parameters of the switchgear in which it is connected. In the secondary circuit in the POMTP, the measurement transformer, due to the need to evaluate relatively small currents, it is necessary to ensure sufficient resolution of the evaluation circuit within the range of values and the current measurement of the continuity of the PEN conductor itself (under unloaded PEN conductor). At the same time, the circuit must also bear the full load (from the load), while distinguishing the absolute value of the current is only necessary to the extent necessary to evaluate the measuring current. The MTP current transformer is used in the circuit for the purpose of determining the path of the closing of the measuring current from the power supply:

1. PEN conductors to the power supply,

2. to the local ground of the PEN of the driver;

3. PEN conductors.

For proper operation of the device, the MTP should be connected (from the point of view of the power supply - eg transformer) before the point of division and local grounding and connection of this device to the PEN wire.

The control unit RJ ensures connection of the measuring circuit at required intervals, evaluates the measuring current, its closing path and controls the signaling unit in case of PEN disconnection of the conductor and power failure. The RJ control unit also includes a test button TT, which is used to run the continuity test of the protective conductor and protective bonding at any time.

The signaling unit S J signals the safe and fault states by sound and light signaling. In case of an uninterrupted PEN wire, the green LED lights up. If the PEN wire break is evaluated, the red LED flashes and a strong, intermittent intermittent beep sounds. In the event of a power failure, the red LED will light and a continuous beep will sound.

PROTECTION REQUIREMENTS

Claims (2)

A protective conductor continuity measuring device (PEN) and (PE), characterized in that the automatic protective conductor continuity measuring device (PE) after the distribution point (ENCE) comprises a power supply (NZE) with a backup battery, which is single-phase in the three-wire wiring which supplies the pulse generator (GIE), which is connected to the conductor (N) and the measured conductor (PE) and to the control unit (RJE), the power supply (NZE) and (MBE2) and a control unit (RJE) equipped with a test button (TT), the outputs from the measuring blocks (MBE1) and (MBE2) are output to the control unit (RJE) and the control unit is connected to the signaling unit (SJE). a device (ENCE), with a device (PENCE) for measuring the continuity of the protective conductor (PEN) before the split point, which consists of a fuse block (BI) connected to the device (ENCE) with rectifier (U), then the block (BI) is connected to the power supply (NZ), which is three-phase and supplies the backup battery (A) and the control unit (RJ), which is equipped with a test button (TT) connected to the measuring circuits (MO1) and (MO2) connected from the rectifier (U), the control unit (RJ) being also connected to the auxiliary circuits (POMTP) of the current transformer (MTP) and also connected to the signaling unit (SJ), which, like the control unit (RJ), is connected to the backup battery (A). Device according to claim 1, characterized in that in a five-wire electrical installation, the power supply (NZE) is single-phase or three-phase. 4 drawings