Distribution networks are classified in 3 main sections according to Grounding Regulation of Electrical Facilities according to grounding type.
- TT Systems,
- IT Systems,
- TN Systems
They examine these three classes in detail; Look at what abbreviations are used in the classification of TN, TT, IT;
► T; Terra = Earth
► N; Notr = Neutral
► I; Isolation = Isolation
► C; Combine = Combination
► S; Separate = Used for separate meanings.
TT and TN are common systems. The IT system is preferred as a local system.
If “TT” is a detailed look at the encoding of these abbreviations;
First letter: Connecting the power system to the soil;
T: Direct connection of a spot to the ground,
I: All tensions are separated from the earth or connected to the earth via an impedance from a point.
Second letter: The connection of the open conductor sections of the installation to the soil;
T: electrically connected directly to the ground, with the open conductive parts, regardless of the grounding of any point of the power system,
N: The direct conduction sections are electrically connected directly to the grounded point of the power system (in A.C. systems, the grounded point of the power system is a neutral (neutral) point, or a neutral (phase) conductor if there is no neutral point).
Some systems can be coded TN-S, TN-C.
This is the 3rd code;
S: A protection function is provided with a separate conductor from the neutral or grounded line conductor (or mains (grounded) in a.a. systems).
A: Combination of neutral and protective safety via a single conductor (PEN conductor).
TN systems have a directly grounded point and the exposed conductive parts of the installation are connected to this point by a protection conductor. The TN system is divided into three types according to the arrangement of neutral and protective conductors:
TN-S system: A separate protection conductor is used throughout the system.
TN-C-S system: Neutral and protection functions are integrated in a single part of the system.
TN-C system: The system is fully neutral and the protection functions are combined in one transmitter.
Figure 1. Conductors as icons
Figure 2. TN-S system
Figure 3. TN-C-S System; The neutral conductor and the protective conductor are combined in a single part of the system.
Figure 4. TN-C System; The system is completely neutral and the protection functions are combined into a single transmitter.
In the TT system there is a directly grounded point, the open conductive parts of the installation are connected to the earth ground which is electrically independent of the power system ground.
Figure 5. TT System
In the IT system, all the tensile parts are separated from the soil or connected to the earth via a point, an impedance. The exposed conductive parts of the electrical installation are separately or jointly grounded or connected to the system ground.
Figure 6. IT System
In the IT type system, an isolation control device is connected to detect the first insulation fault and to protect it from the hazards caused by the second fault. A light or audible signal is given when the first fault occurs. With the insulation control device, no warning is given. If desired, the energy of the network can be disconnected automatically.
Grounding System for Solar Panels
Grounding of photovoltaic systems Since the application areas of photovoltaic systems are always designed to cover the entire surface of the hand, they must be integrated with the existing TT grounding system. Since the application areas of photo-voltaic systems are always designed to cover the whole surface of the hand, they have to be integrated with the existing TT grounding system. For example, in the installation shown in Figure 1 below, there is no supply output protected by the leakage current protection relay on the consumer side. This seems to be a problem to be solved by the network operator at first glance. However, according to DIN VDE 0100-712, it is necessary to have an automatic device which opens circuit in a cable / conductor-fed installation.
In order to enable the electric circuit to be opened with the overcurrent protection devices at an insulation fault such as full body contact, the non-stressed conductive parts of the parts are connected separately to the zero conductor or to a protective conductor which is connected thereto. Purpose of resetting; Avoiding the continuation of high tactile voltages in the body of the drive means.
In order to ensure that the electrical circuit is opened by the overcurrent protection devices at an insulation fault such as full body contact, the non-stressed conductive plant sections are directly connected to the grounding or grounded sections. The purpose of protective grounding is to ensure that the high tactile stress that may occur in conductive plant sections that are not stressed to protect people and other living things from dangerous tactile and step tensions.
Protection grounding is done by connecting the mentioned plant parts to grounding or grounded parts.
Line Protection System
It is a system that provides conductive connection of all non-stressed conductor plant parts to each other and to conductor parts, pipe networks and similar plant parts and star points grounded networks in order to prevent high tensions in insulation lines.
The purpose of using this system is to prevent high contact voltages. This is achieved by connecting all conductive parts of the plant, which are not under tension, to metal parts which can touch each other and to a grounding conductor via a protection conductor.