The directed movement of charged particles, which is called electric current, provides a comfortable existence for modern man. Without it, production and construction facilities, 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. In order to avoid the passage of current through the human body, it is offered another direction with the least losses, which provides grounding or nulling. 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 wayzero 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. If a person touches the body of a refrigerator or washing machine while it is energized, it will not cause electric shock. For this purpose, special sockets with a grounding contact are used.
The principle of operation of the RCD
For the safe operation of industrial and household equipment, residual current devices (RCDs) are used, devices of automatic differential switches are used. Their work is based on comparing the electric current entering through the phase wire and leaving the apartment through the neutral conductor.
Normal operation of an electric circuit shows the same current values in the named sections, the flows are directed in 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.
Breakdown in any part of the insulation leads to the flow of current, directed to the ground, through the damaged place, 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 different settings for tripping the RCD, usuallyadjustment range is from 10 to 300 milliamps. The device works quickly, the shutdown time is seconds.
Operation of the grounding device
To connect the grounding device to the housing of household or industrial equipment, a PE conductor is used, which is output from the shield through 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 grounding of the case has a reliable and permanent effect.
Two way grounding device
Protection and voltage dissipation systems are divided into:
- artificial:
- natural.
Artificial grounds are designed directly to protect equipment and people. For their device, horizontal and vertical steel metal longitudinal elements are required (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 often 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 case of their closest location next to an object or a residential building. Pipelines made of metal in the ground serve as protection. It is impossible to use for the protective purpose of the highway withcombustible 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, grounding is used in some cases, 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, normally not energized, and the output of a single-phase source of electricity, the neutral wire of a 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 housing of industrial or household appliances. A short circuit occurs, blowing fuses and instantaneous automatic shutdown, this is the difference between ground and neutral.
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 housing withphase potential in critical situations. In this case, a current appears that exceeds the rated value of the circuit breaker and the contact stops.
Grounding device
What is the difference between grounding and grounding can be seen from the connection example. The case is connected with a separate wire to zero on the switchboard. To do this, the third core of the electric cable is connected in the socket to 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 provides 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 disconnect 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 diverted directly to the ground, and when zeroed, they are reset to zero in the shield;
- grounding is more effective way to protect a person from electric shock;
- when using groundingsafety is obtained due to a sharp decrease in voltage, and the use of zeroing ensures the shutdown of the section of the line in which there was a breakdown to the body;
- 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 a circuit and deepen it into the ground.
Grounding is a system for dissipating voltage through a triangle in the ground made of a metal profile welded at the junctions. A properly arranged circuit provides reliable protection, but all the rules must be observed. 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 multi-storey buildings, since it is not alwaysit is possible to arrange a reliable and complete grounding.
Grounding does not depend on the phase of the devices, while the zeroing device requires certain connection conditions. In most cases, the first method prevails in enterprises where, according to safety requirements, increased safety is provided. But in everyday life, recently, a circuit has often been arranged to dump the resulting excess voltage directly into the ground, this is a safer method.
Grounding protection applies directly to the electrical circuit, after the 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, the line section is completely turned off.
Grounding is in most cases used in lines with an arranged isolated neutral in IT and TT systems in three-phase networks with a voltage of 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 electrical terms
To understand some of the principles by which protective earthing, grounding and disconnection are performed, you should know the definitions:
A dead-earthed neutral is a neutral wire from a generator or transformer directly connected toground loop.
It can be an output from an AC source in a single-phase network or a pole point of a DC source in two-phase lines, as well as an average output in three-phase DC networks.
Insulated neutral is a neutral wire of a generator or transformer that is not connected to the ground circuit or contacts it through a strong field of resistance from signaling devices, protective devices, measuring relays and other devices.
Accepted designations of grounding devices in the network
All electrical installations with grounding conductors and neutral wires present in them must be marked without fail. Designations are applied to tires in the form of the letter designation PE with alternately alternating transverse or longitudinal identical stripes of green or yellow. 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 symbols
The first letters in the explanation of the system indicate the selected nature of the grounding device:
- T - power supply connection directly to ground;
- I - all current-carrying parts are isolated from the ground.
The second letter is used to describe conductiveparts regarding ground connection:
- T speaks of the mandatory grounding of all open live parts, regardless of the type of connection with the ground;
- N - indicates 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 neutral and N-working conductors is made with separate wires;
- С - one wire is used for protective and working zero.
Types of protective systems
Classification of systems is the main characteristic according to which protective grounding and zeroing 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 IT, TN-C-S, TN-C, TN-S schemes.
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 has been used in some electrical installations to this day.
The TN-C-S and TN-S systems are designed to replace the failed TN-C earthing scheme. In the second protection scheme, two types of neutral wires were separated directly from the shield, and the circuit was complexmetal 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 performed immediately from the transformer, but approximately in the middle of the main. This was not a good decision, because 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 exposed parts of the electrical installation with the presence of current are connected to the earth circuit through an earth electrode that is independent of the neutral wire of the generator or transformer.
The IT system is used to protect the unit, arrange grounding and zeroing. 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 circuit is arranged in special electrical equipment that needs to have increased security and stability, for example, in medical institutions.
Types of grounding systems
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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 neutral wire marked PUE-7.
There is a more advanced zeroing system for electrical installations powered by a single-phase network. In it, the combined common conductor PEN is connected to a solidly grounded neutral in the current source. The separation into N and PE conductors occurs at the branching point of the main to 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.
