Voltage indicator. Rules for use Electrical circuit of the voltage indicator above 1000 V

When checking substation equipment, a high voltage indicator is used. It is necessary to understand the principle of operation of indicators, to study their technical characteristics. Models have an extensive scope, but safety measures should be taken into account.

The high voltage indicator is a mobile device that measures the circuit. The device is universal, there are several varieties:

compact indicators,
single pole options
bipolar devices.

High voltage indicator

Operating principle

The principle of operation is based on tracking the pulses of the circuit. Current is applied to the probe and enters the contact. The indicator part monitors the voltage level and sends a signal to the control board. The models use an insulating part to ensure safety during operation.

Pointer operation

The probe or tip can be connected to a flexible wire or tube. When the voltage exceeds the allowable limits, the indicator may not respond. There are models with and without a screen. Simple options are used with LED lamps.

Specifications

The main characteristics include the following:

minimum operating voltage,
size and weight,
insulating part
maximum working voltage,
ignition threshold.

Indicators to choose from

Application area

The equipment is in demand at enterprises where high voltage installations are used. Most often this is necessary at substations. Thus, there is a need to carry out phasing taking into account the voltage class. It is also possible to test cables, individual power lines.

Power lines

Interesting! It is allowed to check transformers of direct, alternating current.

High voltage indicator device

The main elements of the index are:

tip or probe
insulation,
limit ring,
handle,
thread,
indicator part.

In some cases, a display, contact stabilizers are used. The probe can be mounted on a wire or a holder. The indication can be visual or audible.

Display system

Application rules

Before using the device, it is recommended to check the complete set. On the example of UVNU - 10SZ IP, the tube, insulation, handle are inspected. The nodes must be securely connected, screw fasteners are used. A holder is fixed to the phasing tube. The ring stop must be attached to the body.

Important! An external inspection is necessary in order to identify cracks or delaminations.

Pointer defects

Any defects in the pointer indicate that it is not ready for use. If drops of water or dirt are found on the ring or tube, they must be removed. For this purpose, it is better to use a napkin. Store the device in a dry place, preferably protected from UV exposure.

Particular attention is paid to the probe in the form of a hook. It must be examined without gloves and touched. The indicator of the turned on device should glow intermittently. If a sound is heard, then the device is working. Thus, the resistance of the skin is evaluated, the test is completed.

If the pointer does not respond to human touch, you can try moistening your fingers a little. At sub-zero temperatures, the devices operate with a large error. It is especially problematic to carry out work at a temperature of -20 degrees or more. For the test, it is recommended to select a guaranteed voltage source. The presented pointer captures readings from 100 to 1000 volts.

Voltage source

Important! During the test, you must hold the handle.

When the probe is brought in, it is necessary that it comes into contact with the core. In the normal state, a person will hear an intermittent beep. The lamp will then flash. This confirms that the object is energized. The contact method is needed to determine the phase.

When using signs, an electrician often has to stand on poles. Well, when there is an insulating rod. When working with high-voltage equipment, it is better to use blanks with a length of at least 6 m. The head is necessary for grounding. Touching current-carrying parts is sometimes accompanied by a bright light and a powerful sound signal.

live parts

Before checking the grounding in the installation, the voltage is measured. Permissible energy flow level - 1.5 kV. If the indication does not respond, the pointer must be touched with a non-gloved hand. When the cable is under induced voltage, the indication works in a constant mode. Sometimes it is required to determine the phase, then a working tube is used. It connects to the pointer as well as the pin.

For connection, the shunt is inserted into the hole. There are marks on the pointer, you should not make significant physical efforts. A separate issue concerns operational activities related to testing. The rules are written in the instructions for electrical installations.

electrical installations

Test Goals:

determination of the minimum level of pointer actuation,
longitudinal insulation test,
maximum threshold test

For testing, the pointer is suspended indoors on a hill. The contact probe must be at the bottom. First of all, a slight voltage is applied to the hook, it is important to monitor the light bulb. The maximum limit of the presented modification is 1.5 kW. The longitudinal insulation test allows you to determine the permissible voltage level.

Longitudinal insulation test

Important! The device in good condition can withstand a load of 12 kV.

In this case, the voltage supply time matters. The phasing tube is checked in a similar way. For this purpose, a conductive part with a voltage of 12 kV is brought. However, when the phase is reversed, the parameter is different. It all depends on the resistance of the conductor.

The indication with a tube attached to the pointer is triggered at a load of 1.5 kV. Using the UVNsTF 10I as an example, it can be seen that simple options with a phasing tube are easier to use. The model is suitable for testing cable and overhead lines. When testing electrical installations, it is important to clarify the serviceability of transformers.

Transformer test

Permissible operating voltage should be in the range of 6-10 kV. The pointer phasing tube can only be used in an alternating current circuit. Permissible frequency - from 50 megahertz. According to the manufacturer, the maximum load level is 15 kV. When using the model, contact tips and electrical circuit elements are connected.

Interesting! The pointer has two connecting wires, as well as insulation.

The rod is installed between the bushings, fastening occurs due to the threaded connection. The presented model has a three-digit indication, LED bulbs are used. When voltage is applied to the hook, they light up. It also triggers if a test is performed.

The indicator is able to function in the self-control mode. In this case, the scheme checks the health of the nodes and reports possible errors. When the device is put into operating mode, it becomes possible to automatically determine the type of voltage. Contact with a conductive core is provided by the tip. Determination of polarity does not take much time.

Interesting! The “-” LED is activated when a negative voltage is noted in the current-carrying part. The decrease in frequency is accompanied by a flickering light bulb.

Flickering on the indicator

Security measures

Fundamental rules:

use of electric gloves,
contact is brought to the working part,
rod insulation,
not allowed to use in the rain,
compliance with GOST 20493-2001 standards.

Above, voltage indicators above 1000 V are considered. The differences lie in the design and technical characteristics. For devices, the rules for use and precautions are prescribed in the instructions.

To start installation or repair work at power stations and wires, it is imperative to check the network performance, lack of current or its parameters. For this, a voltage indicator is used, which can determine the presence of voltage and its coincidence up to 1000V.

Description and principle of operation

The high voltage and low voltage indicator is a universal portable type device designed to determine the voltage on current-carrying wires or terminals of individual electrical devices (UVN 10, UNK, UVNK-10, BN-020022 Profipol Benning and others).

This device is necessary when working at various enterprises or when electricians go to the site. The main difference between this pointer and standard meters is that it will help determine only the presence of a load, but not its indicators, unlike models that are installed on a DIN rail.

Photo - indicator with digital display

Basically, only voltage devices up to 1000 Volts are now used, such an indicator can be two-pole and single-pole, they have a similar circuit, but different areas of application. During operation, a device with two poles must be connected to two current-carrying conductors or contacts, while a single-pole device must be connected to only one. You should know that two-pole pointers are more accurate, so they are called high-voltage and are used during complex work.

Photo - UN PIN-90

In addition, there is also a contactless pointer. Testing with it is carried out without connecting to current-carrying terminals. This greatly increases safety during voltage detection. The device is equipped with a digital display, and it notes not only the presence of voltage, but also the approximate size due to the magnetic field.

Photo - single-pole model

There are portable models on batteries and options that require connection to the network (for example, a voltage indicator or indicator of the Contact 55EM type, UVNU-10 kV SZIP, ELIN-1-SZ VL). In the first case, power is supplied using two or more batteries, less often from a battery (these are UVNK, UNNO, UNK, EI-9000/1, Duspol digital LC, Raton). This allows you to use the device on the ground, when leaving or for repair work away from the working power supply network.

Photo - imported UN DT-9902

The principle of operation of the device is quite simple. During connection to the network (by connecting to live parts), a comparison of potentials is made. This raises or lowers the resistance in the pointer resistors. Because of this, the indicator, which consumes the smallest fraction of the amperes flowing in the wires or terminals, lights up or beeps. If the indicator is silent during operation, then there is no load. In some cases, a systematic attenuation of the signal is observed - this means that there was residual energy in the wires.

Requirements for voltage indicators GOST 20493-2001:

For devices up to 1000 volts, the load of the indicators must be no higher than 90 V;
A single-pole device is located in one case, while a two-pole device is located in two, interconnected by a cord;
Any indicator of the presence of a load (onboard, combi and others) must have three surfaces: working, insulated, determining and holder;
In some models, the working part is connected to the indicator;
Verification of indicators is carried out each time before use using a voltage of 2 kV, while it lasts no more than a minute.

It must be remembered that the safety instructions require full preparation before using the device. In particular, it is necessary to put on an energy kit, including dielectric gloves and boots. These requirements are specified for an electrical device, and they differ from the indicator models in UAZ, VAZ and other cars, ships, etc.

Video: UT 15V voltage indicator

Specifications

Voltage indicators for phasing must have certified quality parameters. They depend on the specific model of the device, consider the data on the example of UNNU-40-1000:

The two-pole operating voltage indicator type UNN Combi has parameters similar to UNNDP 12 660 (except for the maximum voltage of 660 V and operating temperatures up to +35):

Photo - UNN Kombi

The two-pole voltage indicator UNN 1, PIN 90, UNK 04, Lotsman-2 and UVNI 150 A has similar technical characteristics. Their quality certificate differs only in terms of load and service life.

Photo - UN Lotsman-2

Parameters of single-pole UVN 80:

Technical data of single-pole UVNBU 6–35:

A very interesting UNVL-0.4 model is used mainly on overhead power lines. It has the following options:

In addition, all models are guaranteed for a year, but only if they are regularly checked before starting work. When buying, always pay attention to the availability of GOST data, a certificate and quality compliance and the possibility of checking before purchasing. Every six months it is necessary to calibrate the sensor on special equipment.

Its feature is that the working contact is made in the form of a hook that clings to the wire, regardless of height. Now there is a newer model for determining voltage on sale - this is the UVNU-10FB Search 1 indicator, where the rod is responsible for fastening contacts on the current-carrying parts of wires or machines. Using this type of device is very simple - the height is adjusted using manual manipulations, in addition, you can fix the length of the retractable part.

Photo - UVNU-10FB Search 1

You can buy a voltage gauge in any city in specialized electrical stores, but the price will depend on who the manufacturer is and the type of device. Two-pole devices are more expensive than single-pole devices. The cost also varies depending on the city of purchase. For example, in Moscow, a certain UN may cost more than in Yekaterinburg or Novosibirsk.

Purpose

2.4.1. Voltage indicators are designed to determine the presence or absence of voltage on the current-carrying parts of electrical installations.

2.4.2. General technical requirements for voltage meters are set out in the state standard.

Voltage indicators above 1000 V

Principle of operation and design

2.4.3. Voltage indicators above 1000 V react to the capacitive current flowing through the indicator when its working part is introduced into the electric field formed by the current-carrying parts of electrical installations that are energized, and the "ground" and grounded structures of electrical installations.

2.4.4. Pointers should contain the main parts: working, indicator, insulating, as well as a handle.

2.4.5. The working part contains elements that respond to the presence of voltage on the controlled current-carrying parts.

Cases of working parts of voltage indicators up to 20 kV inclusive must be made of electrically insulating materials with stable dielectric characteristics. Cases of working parts of voltage indicators of 35 kV and above can be made of metal.

The working part may contain a tip electrode for direct contact with controlled current-carrying parts and not contain a tip electrode (non-contact type pointers).

The indicator part, which can be combined with the working part, contains elements of light or combined (light and sound) indication. Gas-discharge lamps, light-emitting diodes or other indicators can be used as elements of light indication. Light and sound signals must be reliably recognizable. The audio signal should have a frequency of 1 - 4 kHz and an interruption frequency of 2 - 4 Hz when indicating phase voltage. The sound signal level must be at least 70 dB at a distance of 1 m along the axis of the sound emitter.

The working part may also contain an organ of its own control of serviceability. Control can be carried out by pressing a button or be automatic, by periodically supplying special control signals. At the same time, it should be possible to fully check the serviceability of the electrical circuits of the working and indicator parts.

Working parts should not contain switching elements designed to turn on power or switch ranges.

2.4.6. The insulating part of the pointers must be made of the materials specified in clause 2.1.2.

The insulating part may be composed of several links. To connect the links to each other, parts made of metal or insulating material can be used. The use of a telescopic design is allowed, while spontaneous folding should be excluded.

2.4.7. The handle can be one piece with the insulating part or be a separate link.

2.4.8. The design and weight of the pointers should ensure that one person can work with them.

2.4.9. The electrical circuit and design of the pointer must ensure its operability without grounding the working part of the pointer, including when checking the absence of voltage, carried out from telescopic towers or from wooden and reinforced concrete supports of 6-10 kV overhead lines.

2.4.10. The minimum dimensions of the insulating parts and handles of voltage indicators above 1000 V are given in Table. 2.4.

Table 2.4

MINIMUM DIMENSIONS OF INSULATING PARTS AND HANDLES OF VOLTAGE INDICATORS ABOVE 1000 V

2.4.11. The indication voltage of the voltage indicator should not exceed 25% of the rated voltage of the electrical installation.

For pointers without a built-in power supply with a pulse signal, the indication voltage is the voltage at which the signal interruption frequency is at least 0.7 Hz.

For pointers with a built-in power supply with a pulse signal, the indication voltage is the voltage at which the signal interruption frequency is at least 1 Hz.

For other indicators, the indication voltage is the voltage at which there are distinct light (light and sound) signals.

2.4.12. The time of appearance of the first signal after touching the current-carrying part under voltage equal to 90% of the rated phase voltage should not exceed 1.5 s.

2.4.13. The working part of the indicator for a certain voltage should not respond to the influence of neighboring circuits of the same voltage, spaced from the working part at the distances indicated in Table. 2.5.

Table 2.5

DISTANCE TO THE NEAREST WIRE OF THE ADJACENT CIRCUIT

Performance tests

2.4.14. During operation, mechanical tests of voltage indicators are not carried out.

2.4.15. Electrical tests of voltage indicators consist of testing the insulating part with increased voltage and determining the indication voltage.

The test of the working part of voltage indicators up to 35 kV is carried out for indicators of such a design, during operations with which the working part can cause a phase-to-phase short circuit or a phase-to-ground short circuit. The need to test the insulation of the working part is determined by the operating manuals.

For voltage meters with a built-in power source, its condition is monitored and, if necessary, the batteries are recharged or the batteries are replaced.

2.4.16. When testing the insulation of the working part, voltage is applied between the tip electrode and the screw connector. If the pointer does not have a screw connector electrically connected to the indication elements, then the auxiliary electrode for connecting the wire of the test installation is installed at the border of the working part.

2.4.17. When testing the insulating part, voltage is applied between the element of its articulation with the working part (threaded element, connector, etc.) and a temporary electrode applied at the restrictive ring from the side of the insulating part.

2.4.18. The indication voltage of indicators with a gas-discharge indicator lamp is determined according to the same scheme by which the insulation of the working part is tested (clause 2.4.16).

When determining the indication voltage of other indicators with a tip electrode, it is connected to the high-voltage output of the test facility. When determining the indication voltage of pointers without a tip electrode, it is necessary to touch the end side of the working part (head) of the pointer to the high-voltage output of the test setup.

In both latter cases, the auxiliary electrode is not installed on the indicator and the ground terminal of the test set is not connected.

The voltage of the test setup smoothly rises from zero to the value at which the light signals begin to comply with the requirements of clause 2.4.11.

2.4.19. The norms and frequency of electrical testing of pointers are given in Appendix 7.

Terms of use

2.4.20. Before you start working with the pointer, you need to check its serviceability.

The serviceability of pointers that do not have a built-in control body is checked using special devices, which are small-sized sources of increased voltage, or by briefly touching the pointer tip electrode to live parts that are obviously energized.

The serviceability of pointers with a built-in control unit is checked in accordance with the operating manuals.

2.4.21. When checking the absence of voltage, the time of direct contact of the working part of the indicator with the controlled current-carrying part must be at least 5 s (in the absence of a signal).

It should be remembered that, although some types of voltage indicators can signal the presence of voltage at a distance from current-carrying parts, direct contact with them by the working part of the indicator is mandatory.

2.4.22. In electrical installations with voltages above 1000 V, the voltage indicator should be used with dielectric gloves.

Voltage indicators up to 1000 V

Purpose, principle of operation and design

2.4.23. General technical requirements for voltage indicators up to 1000 V are set out in the state standard.

2.4.24. In electrical installations with voltages up to 1000 V, two types of indicators are used: bipolar and single-pole.

Two-pole indicators operating with the flow of active current are designed for electrical installations of alternating and direct current.

Single-pole indicators operating with the flow of capacitive current are intended for electrical installations only with alternating current.

The use of two-pole pointers is preferred.

The use of test lamps to check the absence of voltage is not allowed.

2.4.25. Two-pole pointers consist of two cases made of electrical insulating material, containing elements that respond to the presence of voltage on the controlled current-carrying parts, and elements of light and (or) sound indication. The housings are interconnected by a flexible wire with a length of at least 1 m. In the places of inputs into the housings, the connecting wire must have shock-absorbing bushings or thickened insulation.

The dimensions of the cases are not standardized, they are determined by ease of use.

Each case of a two-pole pointer must have a rigidly fixed tip electrode, the length of the uninsulated part of which should not exceed 7 mm, except for pointers for overhead lines, in which the length of the uninsulated part of the tip electrodes is determined by the technical specifications.

2.4.26. A single-pole pointer has one housing made of electrically insulating material, in which all the elements of the pointer are placed. In addition to the tip electrode that meets the requirements of clause 2.4.25, there must be an electrode on the end or side of the body for contact with the operator's hand.

The dimensions of the case are not standardized, they are determined by ease of use.

The indication of the presence of voltage can be stepped, supplied in the form of a digital signal, etc.

Light and sound signals may be continuous or intermittent and must be reliably recognizable.

For pointers with a pulse signal, the indication voltage is the voltage at which the interval between pulses does not exceed 1.0 s.

2.4.28. Voltage indicators up to 1000 V can also perform additional functions: checking the integrity of electrical circuits, determining the phase wire, determining the polarity in DC circuits, etc. At the same time, the indicators should not contain switching elements intended for switching operating modes.

Expanding the functionality of the pointer should not reduce the safety of operations to determine the presence or absence of voltage.

Performance tests

2.4.29. Electrical tests of voltage indicators up to 1000 V consist of testing the insulation, determining the indication voltage, checking the operation of the indicator at an increased test voltage, checking the current flowing through the indicator at the highest operating voltage of the indicator.

If necessary, the indication voltage in the DC circuits is also checked, as well as the correctness of the polarity indication.

The voltage gradually increases from zero, while the values of the indication voltage and the current flowing through the pointer at the highest operating voltage of the pointer are fixed, after which the pointer is switched off for 1 min. maintained at an increased test voltage exceeding the highest operating voltage of the indicator by 10%.

2.4.30. When testing indicators (except for insulation testing), the voltage from the test apparatus is applied between the tip electrodes (for bipolar indicators) or between the tip electrode and the electrode on the end or side of the housing (for single-pole indicators).

Rice. 2.1. Schematic diagram of testing the dielectric strength of the insulation of the handles and wire of the voltage indicator:
1 - test pointer; 2 - test transformer; 3 - bath with water; 4 - electrode

2.4.31. When testing the insulation of two-pole indicators, both cases are wrapped in foil, and the connecting wire is lowered into a vessel with water at a temperature of (25 +/- 15) ° C so that the water covers the wire, not reaching the handles of the cases by 8 - 12 mm. One wire from the test setup is connected to the tip electrodes, the second, grounded, to the foil and lowered into the water (diagram variant - Fig. 2.1).

For single-pole pointers, the case is wrapped with foil along the entire length to the limit stop. A gap of at least 10 mm is left between the foil and the contact on the end (side) part of the housing. One wire from the test set is connected to the tip electrode, the other to the foil.

Purpose

1. Voltage indicators are designed to determine the presence or absence of voltage on the current-carrying parts of electrical installations.

2. General technical requirements for voltage meters are set out in the state standard.

Voltage indicators above 1000V

Principle of operation and design

3. Voltage indicators above 1000 V react to the capacitive current flowing through the indicator when its working part is introduced into the electric field formed by the current-carrying parts of electrical installations under voltage, and the "ground" and grounded structures of electrical installations.

4. Pointers must contain the main parts: working, indicator, insulating, as well as a handle.

5. Working part contains elements that react to the presence of voltage on the controlled current-carrying parts.

The working part may contain a tip electrode for direct contact with controlled current-carrying parts and not contain a tip electrode (non-contact type pointers).

indicator part, which can be combined with the working one, contains elements of light or combined (light and sound) indication. Light and sound signals must be reliably recognizable.

The working part may also contain an organ of its own control of serviceability. Control can be carried out by pressing a button or be automatic, by periodically supplying special control signals.

6. The insulating part can be a composite of several links. To connect the links to each other, parts made of metal or insulating material can be used. The use of a telescopic design is allowed, while spontaneous folding should be excluded.

7. The handle can be one piece with the insulating part or be a separate link.

8. The design and weight of the signs must ensure the possibility of working with them by one person.

9. The electrical circuit and design of the indicator must ensure its operability without grounding the working part of the indicator, including when checking the absence of voltage, carried out from telescopic towers or from wooden and reinforced concrete supports of 6-10 kV overhead lines.

10. The indication voltage of the voltage indicator should not exceed 25% of the rated voltage of the electrical installation.

11. The time of appearance of the first signal after touching the current-carrying part, which is energized, equal to 90% of the rated phase, should not exceed 1.5 s.

12. The working part of the pointer to a certain voltage should not react to the influence of neighboring circuits of the same voltage.

Performance tests

13. During operation, mechanical tests of voltage indicators are not carried out.

14. Electrical tests of voltage indicators consist of testing the insulating part with increased voltage and determining the indication voltage.

For voltage meters with a built-in power source, its condition is monitored and, if necessary, the batteries are recharged or the batteries are replaced.

15. When testing the insulation of the working part, the voltage is applied between the tip electrode and the screw connector or at the border of the working part.

16. When testing the insulating part, voltage is applied between the element of its articulation with the working part (threaded element, connector, etc.) and a temporary electrode applied at the restrictive ring from the side of the insulating part.

17. The indication voltage of the pointers is checked as follows - the voltage of the test set rises smoothly from zero to a value at which the light signals begin to correspond to 25%.

18. The rates and frequency of electrical testing of pointers are given in the table.

Terms of use

19. Before starting work with the pointer, it is necessary to check its serviceability.

20. When checking the absence of voltage, the time of direct contact of the working part of the indicator with the controlled current-carrying part must be at least 5 s (in the absence of a signal).

It should be remembered that although some types of voltage indicators can signal the presence of voltage at a distance from live parts, direct contact with them the working part of the pointer is mandatory.

21. In electrical installations with voltages above 1000V, the voltage indicator should be used with dielectric gloves.

Voltage indicators up to 1000V

Purpose, principle of operation and design

22. In electrical installations with voltage up to 1000V, two types of indicators are used: two-pole and single-pole.

Two-pole indicators operating with the flow of active current are designed for electrical installations of alternating and direct current.

Single-pole pointers operating with the flow of capacitive current, designed for electrical installations AC only.

The use of two-pole pointers is preferred.

The use of test lamps to check the absence of voltage is not allowed.

23. Two-pole pointers consist of two cases made of electrical insulating material containing elements that respond to the presence of voltage on the controlled current-carrying parts, and elements of light and (or) sound indication. The housings are interconnected by a flexible wire with a length of at least 1 m. In the places of inputs into the housings, the connecting wire must have shock-absorbing bushings or thickened insulation.

The dimensions of the cases are not standardized, they are determined by ease of use.

24. A single-pole pointer has one housing made of electrically insulating material, in which all the elements of the pointer are placed. In addition to the tip electrode that meets the requirements of clause 2.4.25, there must be an electrode on the end or side of the body for contact with the operator's hand.

The dimensions of the case are not standardized, they are determined by ease of use.

Light and sound signals may be continuous or intermittent and must be reliably recognizable.

26. Voltage indicators up to 1000V can also perform additional functions: checking the integrity of electrical circuits, determining the phase wire, determining the polarity in DC circuits, etc. At the same time, the indicators should not contain switching elements intended for switching operating modes.

Expanding the functionality of the pointer should not reduce the safety of operations to determine the presence or absence of voltage.

Performance tests

27. Electrical tests of voltage indicators up to 1000 V consist of testing the insulation, determining the indication voltage, checking the operation of the indicator at an increased test voltage, checking the current flowing through the indicator at the highest operating voltage of the indicator.

If necessary, the indication voltage in the DC circuits is also checked, as well as the correctness of the polarity indication.

28. When testing pointers (except for insulation testing), the voltage from the test facility is applied between the tip electrodes (for bipolar pointers) or between the tip electrode and the electrode on the end or side of the housing (for single-pole pointers).

29. When testing the insulation of two-pole indicators, both cases are wrapped in foil, and the connecting wire is lowered into a vessel with water at a temperature of (25 +/- 15) ° C so that the water covers the wire, not reaching the handles of the cases by 8 - 12 mm. One wire from the test setup is connected to the tip electrodes, the second, grounded, to the foil and lowered into the water.

30. The norms and frequency of operational tests of pointers are given in the table.

Terms of use

31. Before starting work with the pointer, it is necessary to check its serviceability by briefly touching live parts that are obviously energized.

32. When checking the absence of voltage, the time of direct contact of the indicator with the controlled current-carrying parts must be at least 5 s.

33. When using single-pole indicators, contact must be ensured between the electrode on the end (side) part of the body and the operator's hand. The use of dielectric gloves is not allowed.

2.4.20. Before you start working with the pointer, you need to check its serviceability.

The serviceability of pointers with a built-in control unit is checked in accordance with the operating manuals.

2.4.22. In electrical installations with voltages above 1000 V, the voltage indicator should be used with dielectric gloves.

Voltage indicators up to 1000 V Purpose, principle of operation and design

2.4.23. General technical requirements for voltage indicators up to 1000 V are set out in the state standard.

2.4.24. In electrical installations with voltages up to 1000 V, two types of indicators are used: bipolar and single-pole.

Two-pole indicators operating with the flow of active current are designed for electrical installations of alternating and direct current.

Single-pole indicators operating with the flow of capacitive current are intended for electrical installations only with alternating current.

The use of two-pole pointers is preferred.

The use of test lamps to check the absence of voltage is not allowed.

The dimensions of the cases are not standardized, they are determined by ease of use.

The dimensions of the case are not standardized, they are determined by ease of use.

The indication of the presence of voltage can be stepped, supplied in the form of a digital signal, etc.

Light and sound signals may be continuous or intermittent and must be reliably recognizable.

For pointers with a pulse signal, the indication voltage is the voltage at which the interval between pulses does not exceed 1.0 s.

Expanding the functionality of the pointer should not reduce the safety of operations to determine the presence or absence of voltage.