The directional movement of charged particles, which is called an electric current, ensures a comfortable existence for a modern person. Without it, production and construction capacities, medical devices in hospitals do not work, there is no comfort in the home, city and intercity transport is idle. But electricity is a servant of man only in the case of complete control, but if charged electrons can find a different path, then the consequences will be disastrous. To prevent unpredictable situations, special measures are applied, the main thing is to understand what the difference is. Grounding and grounding protect a person from electric shock.
The directional movement of electrons is carried out along the path of least resistance. To avoid the passage of current through the human body, he is offered another direction with the least loss, which provides grounding or grounding. What is the difference between them, to figure out.
Grounding
Grounding is a single conductor or a group made up of them in contact with the ground. With its help, the voltage supplied to the metal case of the aggregates is reset along the path of zero resistance, i.e. to the ground.
Such electrical grounding and grounding of electrical equipment in industry is also relevant for household appliances with steel external parts. Touching a person to the chassis of a refrigerator or a washing machine that has been 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 the safe operation of industrial and domestic equipment , residual current circuit breakers (RCDs) are used, and devices of automatic differential switches are used. Their work is based on a comparison of the electric current entering the phase wire and leaving the apartment along the neutral conductor.
The normal mode of operation of the 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 balanced operation of the devices, 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 a damaged place with a bypass of the working neutral conductor. In the RCD, an imbalance in the current strength is shown, the device automatically turns off the contacts and the voltage disappears in the entire working circuit.
For each individual operating condition, various settings are provided for disconnecting RCDs, usually the adjustment range is from 10 to 300 milliamps. The device works quickly, the shutdown time is seconds.
Grounding device operation
To connect the grounding device to the housing of household or industrial equipment, a PE conductor is used, which is removed from the shield in a separate line with a special output. The design provides the connection of the housing to the ground, which is the purpose of grounding. The difference between grounding and grounding is that at the initial moment when connecting the plug 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 housing has a reliable and permanent effect.
Two way grounding device
Protection and voltage rejection systems are divided into:
Artificial earths are designed directly to protect equipment and humans. Their device requires horizontal and vertical steel metal longitudinal elements (often pipes with a diameter of up to 5 cm or angles 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 quality grounding.
Natural grounding conductors are used in the case of their closest location next to the object or apartment building. As protection are pipelines located in the ground made of metal. Do not use lines with flammable gases, liquids, and pipelines whose outer walls are treated with an anti-corrosion coating for protective purposes.
Natural objects not only protect electrical appliances, but also fulfill their main purpose. The disadvantages of such a connection include access to pipelines of a sufficiently wide range of people from neighboring services and departments, which creates a risk of violation of the integrity of the connection.
Zeroing
In addition to grounding, in some cases they use grounding, it is necessary to distinguish what the difference is. Grounding and grounding remove stress, only do it in different ways. The second method is the electrical connection of the housing, in a normal state, not energized, and the output of a single-phase source of electricity, the zero wire of a generator or transformer, a constant current source at its midpoint. When zeroing, the voltage from the housing is reset to a special distribution panel or transformer box.
Zeroing is used in cases of unforeseen power surges or breakdown of insulation of the case of industrial or household appliances. A short circuit occurs leading to fuses blowing and instantaneous automatic shutdown, this is the difference between grounding and grounding.
Grounding principle
Variable three-phase circuits use the neutral conductor for various purposes. To ensure electrical safety with its help, they get the effect of a short circuit and the voltage that appears on the case with phase potential in critical situations. In this case, a current appears that exceeds the rated value of the circuit breaker and the contact ceases.
Zeroing device
The difference between grounding and grounding is also seen in the connection example. The housing is connected by a separate wire to zero on the distribution panel. For this, the third core of the electric cable is connected to the socket with the terminal provided for this in the socket. This method has a drawback, which requires that a current that is larger than the specified settings is needed for automatic shutdown. If in normal mode the disconnecting device ensures the operation of the device with a current of 16 Amps, then small breakdowns of the current continue to leak without shutting down.
After that, it becomes clear what the difference is between grounding and grounding. The human body, when exposed to a current of 50 milliamps, can not stand it and cardiac arrest will occur. Zeroing against such current indicators may not protect, since its function is to create loads sufficient to disconnect the contacts.
Grounding and grounding, what is the difference?
There are differences between the two methods:
- when grounding, excess current and the voltage that appears on the housing are discharged directly to the ground, and when grounding is reset to zero in the shield;
- grounding is more effective in protecting a person from electric shock;
- when using grounding, safety is obtained due to a sharp decrease in voltage, and the use of grounding ensures that the section of the line in which the breakdown to the housing is turned off
- when performing grounding, in order to correctly determine the zero points and choose a protection method, the help of a specialist electrician will be required, and any home craftsman can make grounding, assemble the circuit and deepen it into the ground.
Grounding is a voltage drainage system through a triangle located in the ground from a metal profile welded at the joints. A properly designed circuit provides reliable protection, but all rules must be followed. Depending on the desired effect, grounding and grounding of electrical installations are selected. The difference between the grounding is that all the elements of the device that are not in a normal mode under current are connected to the neutral wire. Accidental contact of the phase with the zeroed parts of the device leads to a sharp jump in current and equipment shutdown.
In any case, the resistance of the neutral neutral wire is less than the same indicator of the circuit in the earth, therefore, when grounding, a short circuit occurs, which in principle is impossible when using an earthen triangle. After comparing the operation of the two systems, it becomes clear what the difference is. Grounding and grounding differ in the way of protection, since there is a high probability of burning off a neutral wire over time, which must be constantly monitored. Grounding is used very often in multi-storey 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 for the grounding device certain connection conditions are necessary. In most cases, the first method prevails in enterprises where, according to safety requirements, increased safety is provided. But recently, in everyday life, a circuit has often been arranged to discharge the resulting excessive voltage directly into the ground, this is a safer method.
Grounding protection applies directly to the electric circuit, after an insulation breakdown due to the flow of current into the ground, the voltage decreases significantly, but the network continues to operate. When grounding, a section of the line is completely turned off.
Grounding in most cases is used in lines with an isolated neutral in IT and CT systems in three-phase networks with a voltage of up to 1 thousand volts or more than this indicator for systems with a neutral in any mode. The use of grounding is recommended for lines with a grounded dull neutral wire in TN-CS, TN-C, TN-S networks with available N, PE, PEN conductors, this shows what the difference is. Grounding and grounding, despite the differences, are human and instrument protection systems.
Useful Electrical Terms
To understand some of the principles by which protective grounding, grounding and disconnection are performed, you should know the definitions:
Blind neutral is a neutral wire from a generator or transformer directly connected to the ground loop.
It can be output from an AC source in a single-phase network or the pole point of a DC source in two-phase mains, as well as the average output in three-phase DC networks.
An isolated neutral is a zero wire of a generator or transformer, not connected to the grounding circuit or in contact with it through a strong resistance field from signaling devices, protective devices, measuring relays and other devices.
Accepted designations of grounding devices in the network
All electrical installations with earth conductors and neutral wires present in them must be marked. Designations are applied to tires in the form of the letter designation PE with alternating alternating transverse or longitudinal identical stripes of green or yellow. Neutral neutral conductors are marked with a blue letter N, so grounding and grounding are indicated. The description for protective and working scratch consists in affixing the letter PEN and painting in blue over the entire length with green-yellow tips.
Letter designations
The first letters in the system description indicate the selected nature of the grounding device:
- T - connection of the power source directly to the ground;
- I - all live parts are isolated from the ground.
The second letter is used to describe the conductive parts regarding connection to earth:
- T speaks of the mandatory grounding of all exposed parts under voltage, regardless of the type of connection with the ground;
- N - means that the protection of exposed parts under current is carried out directly through a grounded neutral from the power source.
The letters standing across 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 by separate wires;
- C - for protective and working zero, one wire is used.
Types of protective systems
Classification of systems is the main characteristic by 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 performed according to the IT, TN-CS, TN-C, TN-S schemes.
The TN-C system was developed in Germany at the beginning of the 20th century. It provides for the combination of a working neutral wire and a PE conductor in one cable. The disadvantage is that when zero is burned out or other disturbed connection occurs, voltage appears on the equipment cases. Despite this, the system is used in some electrical installations to our time.
The TN-CS and TN-S systems are designed to replace the failed TN-C ground circuit. In the second protection scheme, two types of neutral wires were separated directly from the shield, and the circuit was a complex metal structure. This circuit turned out to be successful, since when disconnecting the neutral wire, the line voltage did not appear on the casing of the electrical installation.
The TN-CS system is characterized in that the separation of the neutral wires is not carried out immediately from the transformer, but approximately in the middle of the trunk. This was not a good solution, because if a zero break occurs before the separation point, then the electric current on the case will be a threat to life.
The TT system connection scheme provides direct connection of live parts to the ground, while all open parts of the installation with the presence of current are connected to the soil circuit through an earthing switch, which does not depend on 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 such a connection from the previous circuit? In this case, the transfer of excessive voltage from the housing and open parts occurs to the ground, and the source neutral, isolated from the ground, is grounded by means of devices with high resistance. This scheme is arranged in special electrical equipment, which should have increased safety and stability, for example, in medical institutions.
Types of Zeroing Systems
The PNG grounding system is simple in design, in it the neutral and protective conductors are combined along the entire length. It is for the combined wire that the indicated abbreviation is used. The disadvantages include increased requirements for the harmonious interaction of potentials and the conductor cross section. The system has been successfully used to neutralize three-phase networks of asynchronous units.
It is not allowed to carry out protection according to such a scheme in group single-phase and distribution networks. The combination and replacement of the functions of the neutral and protective cables in a single-phase DC circuit is prohibited. They use an additional neutral wire marked PUE-7.
There is a more advanced grounding system for electrical installations powered by a single-phase network. In it, the combined common conductor PEN is connected to a grounded neutral in the current source. The separation into N and PE conductors occurs at the branching point of the line into single-phase consumers, for example, in the access panel 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 explained simply, the concept does not require special knowledge. But in any case, measures to maintain the safety of household electrical appliances or industrial equipment should be carried out constantly and at the proper level.