What is the difference between grounding and grounding. Grounding and zeroing, what is the difference, and how to ensure the safe operation of electrical appliances

Protective grounding is the combination of parts of electrical installations that are not energized with a grounded wire of a power source or with a grounded neutral of a generator or three-phase transformer winding. That is, it is the connection of the metal part of the electrical appliance with the neutral of the transformer. Since in this case the neutral is grounded, grounding can be considered a type of grounding. The principle of operation differs from grounding in that in this case there is short circuit. The use of this method allows you to reduce the resistance on the phase-zero loop. If the voltage of one of the phases is supplied to the motor housing, then a short circuit occurs. And this, in turn, causes the fuse or other protection device to operate. If there is no protective zeroing, then the current strength, due to the fact that the resistance is large, may be small for the protection device to operate. Thus, a damaged household appliance can be under voltage for a long time, dangerous to humans. In this article we will consider the device, purpose and principle of operation of protective zeroing.

Operating principle

What is the principle of the system? When the phase hits the body of the device, which is made of metal and connected to the neutral conductor, occurs. At the same time, the current strength increases and the protection devices are triggered. Due to this, the electrical lines are turned off, which feed the electrical appliance.

According to the PUE, a damaged power line in automatic mode should be turned off within 0.4 seconds and no more (in a 380/220 V network). For this action, as a rule, special conductors are used, the purpose of which is to protect. For example, if the wiring is single-phase, then this may be the third core of the wire or cable.

In this case, the phase-zero loop should be with little resistance. This is necessary in order for the protective device to operate within a certain time. Therefore, protective grounding will be effective only if the installation of the network and connections are correct and made with high quality.

The diagram below shows the principle of operation and application of the system:

The purpose of such a device makes it possible to quickly disconnect the faulty line from electricity, and at the same time provide low voltage on the body of the electrical appliance. Due to this electric shock of the human body is impossible.

Based on this, it follows that the principle of zeroing operation is based on the operation of a circuit breaker due to a short circuit to the device case and, as a result, disconnection of the affected electrical appliance from the electrical network. A diagram of how the system works when an insulation breakdown occurs is shown below:

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Application area

Protective grounding is used in electrical appliances and installations with four-wire electrical networks and with voltage up to 1 kV:

• in power networks with alternating current and with one phase, in which the output is grounded;
• in power networks with direct current, in which the middle point of the source is grounded;
• in power networks with alternating current and with three phases, in which zero is grounded (TN - S), these networks are usually the following: 220/127, 660/380, 380/220 V.

The use of an electrical network with a voltage of 380/220 is possible in all structures that have protective zeroing electrical appliances mandatory. If these are residential premises with dry floors, then such protection is not necessary.

Electrical installations with a voltage of 220/127 V and their protective grounding have been used in special rooms where electric shock is possible. In outdoor electrical installations that are located in hazardous areas, metal parts that the operating personnel can touch during the work process are zeroed.

Purpose

Such a device is necessary in order to protect against electric shock. In a word, protective grounding plays an important role in the implementation of electrical safety at home.

But such a device can be dangerous at home. According to the PUE, it is not safe to use it in everyday life. For example, if you perform such protection in an outlet, this will lead to serious consequences. The purpose of the outlet is to quickly connect household appliances to electricity. But if the purpose for a person does not play a role and the circuit where there is a switching device, it is forbidden to use it as a protective conductor. And the danger lies in the fact that if the integrity of zero in electrical appliances is violated, then they will be under high voltage.

If, however, it happens in such an outlet, then when you turn on, for example, a boiler, a person will be electrocuted. If there is a zero break in a multi-storey building, then a low voltage will go to one part of the apartments, and an increased voltage will go to the second. Such a distribution is fraught with household appliances in apartments.

It should also be remembered that grounding is extremely dangerous in a two-wire system. For example, when repair work, an electrician can change the neutral wire to phase. After all, in electrical panels such veins often do not have any distinctive coloration. Therefore, if you swap the phase and zero, then electrical appliances will be energized.

All kinds of electrical appliances occupy an integral place in our life. Breakdown of any electrical equipment is a frequent and quite normal phenomenon, because any device cannot work forever and without failure. Ensuring safety against short circuit in order to protect the body from damage by high voltage is the main task of everyone.

Concept definitions

According to safety regulations, certain parts of the electrical installation must be protected by barriers, mesh barriers or special covers, as they must be energized due to specifications. BUT in case of accidental damage to the insulation, to prevent electric shock, use protective grounding or grounding. You need to know the difference between them, how these protection options differ from each other. Let's take a look at what they are.

Grounding is a grounding device with barriers, with a special electrical connection of metal parts of electrical installations.

A rather large part of the current, as a result of the installation of the grounding device, enters the case and leaves through the ground electrode, whose resistance is less than the rest of the sections electrical circuit. A grounding conductor is a conductor or a set of conductors that are interconnected and are in direct contact with the ground.

Zeroing is a metal part of electrical equipment that is electrically connected and are under low voltage., namely with deafly grounded:

• output of a single-phase current source;
• the neutral of a three-phase current generator or transformer;
• midpoint of the DC source.

This means that any excessive power surges. This is applicable for the case when insulation breakdown occurs and current enters a non-current-carrying part of the equipment. Then a short circuit occurs, which leads to burnout fuses, to the instantaneous operation of the circuit breaker or the reaction of other protection systems.

When grounding is applied, voltage and excess current are output directly to the ground. This method- this is a drainage system, the end point and ground loop of which is a triangle located in the ground about five meters. It is made of powerful metal rods and connected by welding to each other. To reduce the voltage of the electric current when touching the electronic installation, grounding is used, however, the effectiveness of this protection depends on the quality of the ground loop.

When grounding the body of the electrical installation, including all its elements that are not in normal condition under tension connected to the neutral wire. In case of accidental contact of the phase conductor with zeroed parts, the current increases sharply, a short circuit occurs, and the electrical installation is disconnected from the power source.

The resistance of high-quality grounding will always be higher than the resistance of the neutral wire, as a result of which a short circuit occurs, which cannot occur with this method. A less effective method of protection prevails at zeroing, because there is always a possibility that the neutral conductor will burn out, it needs constant monitoring. However, if it is possible to install protective earth missing, it is often used.

Grounding Benefits

Grounding is considered more efficient And safe method protection compared to zeroing:

1. With the help of a rapid decrease in the voltage of the electric current when grounding, electrical safety is ensured. And electrical safety during zeroing is created by turning off the circuit section, where insulation breakdown occurs;
2. To equip the zeroing, one cannot do without special skills and technical knowledge. This will be required for the correct determination of the grounding point of electrical equipment and the correct choice of the grounding method. No special knowledge is required to install a protective earth, you just need to act based on the instructions for the devices. The methods of grounding protection do not depend on the phase of electrical devices and there are no differences at all.

Conclusion

Based on this, we can summarize - it is quite simple and quite correct to equip with your own hands grounding in a private house, this system is more safe and durable. And if we take the zeroing, then for its installation it is necessary to call the master and a constant inspection of the integrity of the neutral wire is required, which is considered a big minus when comparing the differences. This method is considered suitable for use in old Khrushchev, where the contour of the "earth" simply does not exist.

The difference between grounding and grounding is significant. Let's try to understand this issue. Zeroing according to the PUE is a deliberate protection that is used exclusively for industrial purposes and should not be practiced at the household level.

But still, very often, zeroing is done in apartments. According to all forecasts, such a system is far from perfect and not at all safe. Why, then, resort to such an extreme measure? Partly due to a lack of knowledge in this area, or because of a hopeless situation.

During the repair of an apartment, many make a complete or partial electrical installation, not only for the convenience of the location of sockets and switches, but also to replace worn-out electrical wiring. Also, a modern person wants to make his home safer, therefore, the wishes of the customer come down to ensuring that the house has grounding.

What is used in new buildings: grounding or grounding?

New buildings, by all rules, are provided with a three-wire cable (phase, zero, earth) in a single-phase system and a five-wire cable (three phases, zero, earth) in a three-phase system, i.e. according to the TN-C-S or TN-S earthing system. In such systems, zeroing does not smell.

Is it possible to make grounding in the old fund?

The old foundation is very rarely reconstructed. In order to transfer from the TN-C system, i.e. two-wire system (phase and zero), for such efficient systems as TN-C-S and TN-S, in which a protective conductor PE (ground) is provided, it is practically impossible on your own. Modernization is mainly carried out by a specialized electrical company.

IN TN-C system no protective conductor (ground). No one will pull a separate ground wire from their apartment in order to make grounding, for example, in the basement. Although, some decide to provide themselves with grounding if the apartment is located on the first floor. But for the majority of the population, such a maneuver is not possible.

Before connecting the protective conductor PE (ground) from the apartment, you need to determine what possibilities are available. Determine the presence of grounding in the switchboard, to which a third conductor can be connected. The switchboard room must either have a PE ground bus, or all floor switchboard rooms must be interconnected by a metal bus, and as a result connected to the common ground loop of the house, i.e. It's about re-grounding. This makes it possible to connect a grounding conductor from the apartment to the shield. If these two options are absent, then there is no grounding in the house, and in this case, a prohibited grounding is done. As mentioned earlier, this method in the residential sector is not at all safe.

How is nulling done?

Zeroing does not play the role of grounding, such a circuit is designed for the effect of a short circuit. In production, the loads are more or less evenly distributed, and zero performs mainly protective functions. Here, the neutral conductor is hooked to the motor housing. If the voltage of one of the phases hits the motor housing, a short circuit will occur. In turn, the circuit breaker or differential protection circuit breaker will trip. One more indisputable fact should be taken into account - all electrical installations in production are interconnected by a metal ground bus and brought to a common ground loop of the entire building.

Is it possible to make zeroing in the apartment?

It is possible, but not necessary. What does it threaten? Suppose your equipment (washing machine, boiler, etc.) is zeroed. If the neutral wire burns for some reason or the electrician accidentally mixed up the wire connection (connected the phase instead of zero), then your equipment will simply burn out due to high voltage.

If you have planned electric installation work in your home, and then you find out that there is no grounding in the house in any form, it is still better to lay a three-core cable. We connect two cores (phase and zero) as planned, but leave the third conductor of the protective earth unused until waiting for the reconstruction of the risers, where grounding will be provided.

If you still decide to make a zeroing in the apartment, you need to remember that you are taking on a huge responsibility. In any case, in the presence of grounding or zeroing, the installation of protective equipment, such as an RCD (residual current device) and a voltage limiter, cannot be neglected.

When buying any electrical equipment, whether it is a washing machine or a refrigerator, it is not designed for a lifetime and, like any other equipment, can break down during operation. To protect electrical equipment from abnormal operating modes (overload or short circuit), various protective devices (automatic devices, plugs, etc.) are used.

But there are situations when protective devices do not respond to damage. One such case is damage to the internal insulation and the occurrence of high voltage equipment on the metal case.

In this case, protection is necessary for the person himself, who will become energized by touching the damaged equipment. To protect against such damage, grounding was invented, the main purpose of which is to reduce the magnitude of this voltage.

That is, the main purpose of grounding- reduce the contact voltage to a safe value.

Suppose you have at home ceiling lamp, the case of which is not connected to ground. As a result of damage to the insulation, the metal part of the lamp was energized. At the moment when you try to change the light bulb, you will be shocked, because by touching the case you become a conductor and electricity will flow through your body into the ground.

If the lamp is grounded, most of current will flow into the ground through the ground wire and at the moment of contact, the voltage on the case will be much less, and, accordingly, the amount of current passing through you will also be less.

grounding- the connection of metal non-current-carrying parts of an electrical installation to the ground (ground loop) is called, which are not normally energized, but may be due to damage to the insulation.

Also, grounding is necessary for the functionality of devices such as RCDs. If the housings of electrical installations are not connected to the ground, then the leakage current will not flow, which means that the RCD will not respond to a malfunction.

The difference between grounding and grounding

Along with grounding, you have probably heard such a term as zeroing.

Zeroing- is called the connection of metal non-current-carrying parts of an electrical installation with zero (neutral conductor of the network).

In my own way purpose grounding and grounding perform the same task - protect a person from electric shock. However, they provide little protection. different ways. In networks with zeroing, electrical equipment is disconnected from the network, the case of which, due to insulation breakdown, was energized.

Consider an example in which the protection of an electrical installation is ensured by means of zeroing.

As can be seen from the figure, during a phase breakdown on a case connected to zero, closed loop between phase and zero, that is, a single-phase short circuit. Protective devices, such as circuit breakers or fuses, react to the resulting short circuit, as a result, the damaged electrical installation is disconnected from the power source.

The above examples make it possible to conclude that:

Surely you have a question in which cases grounding protection is performed, and in which zeroing. Application in different occasions grounding and grounding caused different systems grounding of electrical installations. In electrical installations with voltages up to 1000 V, five grounding systems are used: TN-C, TN-S, TN-C-S, TT, IT.

Zeroing is used as protection in systems in which there is a PEN, PE or N conductor. These are networks with a deafly grounded neutral, TN-C, TN-S and TN-C-S.

The directed movement of charged particles, which is called electric current, provides a comfortable existence modern man. Without it, production and construction capacities, medical devices in hospitals do not work, there is no comfort in the home, urban and intercity transport is idle. But electricity is the servant of man only in the case of complete control, but if the charged electrons can find another way, then the consequences will be dire. To prevent unpredictable situations, special measures are used, the main thing is to understand what the difference is. Grounding and zeroing protect a person from electric shock.

The directed movement of electrons is carried out along the path of least resistance. To avoid the passage of current through the human body, it is offered another direction with the least loss, which provides grounding or zeroing. What is the difference between them remains to be seen.

grounding

Grounding is a single conductor or a group made up of them, which is in contact with the ground. With its help, the voltage supplied to the metal case of the units is reset along the path of zero resistance, i.e. to the ground.

Such electrical grounding and zeroing of electrical equipment in the industry is also relevant for household appliances with steel outer parts. A person touching the refrigerator body or washing machine energized will not cause electric shock. For this purpose, special sockets with a grounding contact are used.

The principle of operation of the RCD

For safe work industrial and household equipment is used, they use devices of automatic differential switches. Their work is based on a comparison of the electric current entering through the phase wire and leaving the apartment through the neutral conductor.

The normal operation of the electrical circuit shows same values current in the named sections, the flows are directed to opposite directions. In order for them to continue to balance their actions, ensure the balanced operation of devices, they perform the installation and installation of grounding and grounding.

A breakdown in any section of the insulation leads to the flow of current directed to the ground through the damaged area, bypassing the working neutral conductor. The RCD shows an imbalance in the current strength, the device automatically turns off the contacts and the voltage disappears in the entire working circuit.

For each individual operating condition, there are various settings to trip the RCD, typically the setting range is 10 to 300 milliamps. The device works quickly, the shutdown time is seconds.

Operation of the grounding device

To attach to the housing of a household or industrial equipment a PE conductor is used, which is output from the shield along a separate line with a special output. The design provides connection of the body to the ground, which is the purpose of grounding. The difference between grounding and zeroing is that at the initial moment when the plug is connected to the outlet, the working zero and phase are not switched in the equipment. The interaction disappears at the last minute when the contact opens. Thus, the chassis grounding has a reliable and permanent effect.

Two way grounding device

Protection and voltage tap systems are divided into:

• artificial:
• natural.

Artificial grounds are designed directly to protect equipment and people. Their device requires horizontal and vertical steel metal longitudinal elements (often pipes with a diameter of up to 5 cm or corners No. 40 or No. 60 with a length of 2.5 to 5 m are used). Thus, grounding and grounding are different. The difference is that a specialist is required to perform high-quality grounding.

Natural grounding conductors are used in the case of their closest location next to the object or residential building. Pipelines made of metal in the ground serve as protection. It is impossible to use for the protective purpose lines with combustible gases, liquids and those pipelines, the outer walls of which are treated with an anti-corrosion coating.

Natural objects serve not only to protect electrical appliances, but also fulfill their main purpose. The disadvantages of such a connection include access to pipelines by a sufficiently wide range of people from neighboring services and departments, which creates a danger of violating the integrity of the connection.

Zeroing

In addition to grounding, in some cases zeroing is used, you need to distinguish what the difference is. Grounding and zeroing divert voltage, they just do it in different ways. The second method is the electrical connection of the case, in the normal state not energized, and the output of a single-phase source of electricity, the neutral wire of the generator or transformer, a source of direct current at its midpoint. When zeroing, the voltage from the case is reset to a special switchboard or transformer box.

Zeroing is used in cases of unforeseen power surges or breakdown of the insulation of the case of industrial or household appliances. A short circuit occurs, leading to blown fuses and instantaneous automatic shutdown, this is the difference between grounding and neutralizing.

Zeroing principle

Variable three-phase circuits use a neutral conductor for various purposes. To ensure electrical safety, it is used to obtain the effect of a short circuit and the voltage that has arisen on the case with phase potential in critical situations. In this case, a current appears that exceeds the nominal value. circuit breaker and contact is terminated.

Zeroing device

The difference between grounding and grounding can be seen from the connection example. The case is connected with a separate wire to zero on To do this, the third core is connected in the socket electric cable with the terminal provided for this in the socket. This method has the disadvantage that the automatic shutdown requires a current that is larger than the specified setting. If in normal mode the disconnecting device ensures the operation of the device with a current of 16 amperes, then small breakdowns of the current continue to leak without tripping.

After that, it becomes clear what is the difference between grounding and grounding. The human body, when exposed to a current of 50 milliamps, may not withstand and cardiac arrest will occur. Zeroing from such current indicators may not protect, since its function is to create loads sufficient to turn off the contacts.

Grounding and zeroing, what's the difference?

There are differences between these two methods:

• when grounding, the excess current and the voltage that has arisen on the case are discharged directly to the ground, and when zeroed, they are reset to zero in the shield;
• grounding is more effective ways in the issue of protecting a person from electric shock;
• when using grounding, safety is obtained due to a sharp decrease in voltage, and the use of zeroing ensures that the section of the line in which a breakdown has occurred to the case is turned off;
• when performing zeroing, in order to correctly determine the zero points and choose the protection method, you will need the help of a specialist electrician, and any home craftsman can make grounding, assemble the circuit and deepen it into the ground.

Grounding is a system for diverting voltage through a triangle located in the ground from metal profile welded at the joints. A properly arranged circuit gives reliable protection but all the rules must be followed. Depending on the desired effect, grounding and zeroing of electrical installations are selected. The difference between zeroing is that all elements of the device that are not under current in normal mode are connected to the neutral wire. Accidental contact of the phase with zeroed parts of the device leads to a sharp jump in current and shutdown of the equipment.

The resistance of the neutral neutral wire is in any case less than the same indicator of the circuit in the ground, therefore, when zeroing, a short circuit occurs, which is basically impossible when using an earth triangle. After comparing the operation of the two systems, it becomes clear what the difference is. Grounding and zeroing differ in the method of protection, since there is a high probability of the neutral wire burning out over time, which must be constantly monitored. Zeroing is used very often in high-rise buildings, since it is not always possible to arrange a reliable and complete grounding.

Grounding does not depend on the phase of the devices, while the grounding device requires certain connection conditions. In most cases, the first method prevails in enterprises where, according to safety requirements, increased security. But also in everyday life Lately often a circuit is arranged to discharge the resulting excess voltage directly to the ground, this is a safer method.

Grounding protection directly concerns the electrical circuit, after a breakdown of the insulation, due to the flow of current into the ground, the voltage is significantly reduced, but the network continues to operate. When zeroing, a section of the line is completely turned off.

Grounding is in most cases used in lines with an isolated neutral in IT and TT systems in three-phase networks with voltages up to 1 thousand volts or more for systems with a neutral in any mode. The use of grounding is recommended for lines with a grounded dead neutral wire in TN-C-S, TN-C, TN-S networks with available N, PE, PEN conductors, this shows the difference. Grounding and zeroing, despite the differences, are human and instrument protection systems.

Useful terms of electrical engineering

To understand some of the principles by which protective earthing, grounding and disconnection are performed, you should know the definitions:

A solidly grounded neutral is a neutral wire from a generator or transformer that is directly connected to a ground loop.

It can serve as an output from the source alternating current in a single-phase network or the pole point of a DC source in two-phase lines, as well as the average output in three-phase DC networks.

An insulated neutral is a neutral wire of a generator or transformer that is not connected to the ground loop or is in contact with it through strong field resistance from signaling devices, protective devices, measuring relays and other devices.

Accepted designations in the network

All electrical installations with grounding conductors present in them and neutral wires in without fail are subject to labeling. Designations are applied to tires in the form letter designation PE with alternating transverse or longitudinal identical stripes of green or yellow color. Neutral neutral conductors are marked with the blue letter N, which is how grounding and grounding are indicated. The description for the protective and working zero is to affix the letter designation PEN and color it in a blue tone throughout with green-yellow tips.

Letter designations

The first letters in the explanation to the system indicate the selected nature of the grounding device:

• T - connection of the power source directly to the ground;
• I - all current-carrying parts are isolated from the ground.

The second letter is used to describe the conductive parts in relation to the connection to earth:

• T speaks of the mandatory grounding of all open live parts, regardless of the type of connection with the ground;
• N - means that the protection of open parts under current is carried out through a solidly grounded neutral from the power source directly.

The letters through the dash from N indicate the nature of this connection, determine the method of arranging the zero protective and working conductors:

• S - PE protection of the zero and N-working conductors is made with separate wires;
• C - one wire is used for protective and working zero.

Types of protective systems

The classification of systems is the main characteristic according to which protective grounding and grounding are arranged. General technical information is described in the third part of GOST R 50571.2-94. In accordance with it, grounding is carried out according to the schemes IT, TN-C-S, TN-C, TN-S.

The TN-C system was developed in Germany at the beginning of the 20th century. It provides for combining a working neutral wire and a PE conductor in one cable. The disadvantage is that when zero burns out or another connection failure occurs, voltage appears on the equipment cases. Despite this, the system is used in some electrical installations to this day.

The TN-C-S and TN-S systems are designed to replace the failed TN-C grounding scheme. In the second protection scheme, two types of neutral wires were separated directly from the shield, and the circuit was complex metal structure. This scheme turned out to be successful, since when the neutral wire was disconnected, line voltage did not appear on the casing of the electrical installation.

The TN-C-S system is different in that the separation of the neutral wires is not carried out immediately from the transformer, but approximately in the middle of the main. It was not good decision, since if a zero break occurs before the separation point, then the electric current on the case will be life threatening.

The TT connection scheme provides a direct connection of live parts to earth, while all open parts of the electrical installation with the presence of current are connected to the earth circuit through an earthing conductor, which is independent of the neutral wire of the generator or transformer.

According to the IT system, the unit is protected, grounding and grounding are arranged. What is the difference between this connection and the previous scheme? In this case, the transfer of excess voltage from the housing and open parts occurs to the ground, and the source neutral, isolated from the ground, is grounded by means of high resistance devices. This scheme is arranged in a special electrical equipment, which should have increased security and stability, for example, in medical institutions.

Types of grounding systems

The PNG nulling system is simple in design, it nulls and protective conductors combined throughout. It is for the combined wire that the indicated abbreviation is used. The disadvantages include increased requirements for the well-coordinated interaction of potentials and the conductor cross section. The system is successfully used for zeroing three-phase networks of asynchronous units.

It is not allowed to perform protection according to this scheme in group single-phase and distribution networks. It is forbidden to combine and replace the functions of the neutral and protective cables in a single-phase DC circuit. They use an additional one marked PUE-7.

There is a more advanced zeroing system for electrical installations powered by. In it, the combined common conductor PEN is connected to the current source. The division into N and PE conductors occurs at the point of branching of the main into single-phase consumers, for example, in the access shield of an apartment building.

In conclusion, it should be noted that protecting consumers from electric shock and damage to electrical household appliances during power surges is the main task of energy supply. The difference between grounding and grounding is simply explained, the concept does not require special knowledge. But in any case, measures to maintain the safety of household electrical appliances or industrial equipment must be carried out constantly and at the proper level.