Electricity, as everyone knows, is very beneficial for society, but although it is very advantageous it also poses a very high danger to humanity. And to combat this danger, the electrical grounding system was created. In this article we will talk about what is grounding, what is its function, we will talk about the types of grounding and teach how to do a simple grounding.
But before we understand what ground is, we need to know some concepts.
Electrical potential also is known as an electrical voltage, is an electrical quantity. By definition, the electrical potential is the force required to move electrons and produce an electric current.
Voltage can also be defined as the potential difference between two points, a difference that makes the electrons from the negatively charged point move to the positively charged point, thus creating an electric current.
Power leakage occurs when the passage of electrical current from a circuit, instead of returning to the circuit, escapes through a point that has a potential difference or a grounded point.
Leakage of energy is what often does not allow the measurement of electrical voltage to be accurate. This leak occurs for many reasons, equipment problems, poor insulation, sound insulation, moisture, damaged components, among others.
The most dangerous way to leak energy is when the current escapes through a human body. When someone touches an energized surface or equipment, because we are in constant contact with the earth, we become a grounded point and because there is no other point with less resistance, the current escapes through the body and causes an electric shock.
Electrical grounding: What is it?
Know what an Electrical Ground is!
Electrical grounding or just grounding is a protection and safety system, a system that places installations and equipment at the same potential, so that the potential difference between the equipment and the earth is as close to zero as possible.
As it is the safest way to interfere with electricity, grounding is mandatory according to the NBR 5410 standard, which says that every building must have a grounding infrastructure, but unfortunately, most buildings have no grounding.
The lack of grounding is most often caused by a lack of information because most electricians do not know how to make an efficient grounding, even if it is simple.
Grounding ensures the proper functioning of a circuit when it performs its functions.
Electrical grounding: Functions
Among the functions of grounding, we can mention the three main ones, which are protecting the user, making it easier for protection devices to fulfill their functions and protecting against atmospheric and electrostatic discharges.
As explained earlier, when someone touches energized equipment, that person suffers an electric shock for being the grounded point, but when the ground is placed on such a device it offers an electrical resistance much lower than that of the human body.
The person who touched the equipment still suffers an electrical discharge, but in much smaller proportions that are not life-threatening, because most of the electrical current went to where it had less resistance, that is, it went to ground.
Make it easier for protective devices to do their job
When there is no ground, the excess energy of equipment would only be dissipated when someone touched the frame of this equipment, however with a grounding system, this excess energy would go to the ground and cause an increase in current that would trip the circuit breaker or the protection device.
Protection against electrostatic and atmospheric discharges
Electrostatic charges are produced through friction. Equipment and circuits are subject to friction at all times, either through the air or for another reason, this friction generates static charges and these charges accumulate in the equipment’s housing, which can cause a shock.
Upon grounding, these electrostatic charges would seep through the conductor and go to earth, preventing accidents.
Another form of discharge is lightning. When a storm generates lightning, there is a possibility that it will hit some equipment, a house or an establishment and cause serious damage, in these cases the grounding protects the user and the equipment by offering an alternative path to the lightning current.
Types of Electrical Grounding
Basically there are three types of grounding, IT, TT and TN, which is
branched into TN-C, TN-S, TN-CS.
First: Letter referring to food in relation to land.
T- A point directly grounded.
I- Isolation of live parts in relation to earth or ground with resistance.
Second: Letter referring to the equipment and devices installed in relation to the earth.
T- Masses or loads directly grounded, separated from the power ground.
N- Masses or loads connected directly to the supply ground, whose grounded cable is neutral.
Letters related to neutral and protective conductor
S- The neutral conductor and the protective conductor are different.
C- Only one conductor to perform the neutral and protection function.
In this system, the supply may or may not be grounded, if it is, it is grounded through a high resistance that limits the current flow and prevents the protection devices from disarming at first. The grounding of the masses can be done on the same electrode as the supply ground.
It type grounding
See an IT grounding scheme!
In this system, the point coming from the feed is directly grounded and the masses have their own grounding, connected to an infrastructure different from the grounding infrastructure of the food.
Grounding type tt
See a TT type earthing scheme!
This system has the supply directly grounded, and the masses or loads are connected to the supply ground by a conductor. This system branches into three, changing the relationship between the neutral cable and the protection cable.
In this grounding, the neutral is grounded, but it does not only have the neutral function but also the earth function, since for both functions the neutral grounding conductor that is grounded is used.
Grounding type tn_c
See a grounding scheme of type TN_C!