TECHNICAL NOTE ABOUT POWER SYSTEM NETWORKS
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TecnoVeritas deals with power supply systems nearly every day. So, we would like to share with you all some key concepts of these systems. On this article,we will focus on ???? Earthing system in general.
The earthing system sets the relative potential of the electrical conductors to the Earth's conductive surface (i.e. the ground). There are three kinds of earthing designs recognized in IEC 60364?standard, using the two-letter codes TN, TT and IT.
The first letter refers to the connection between the earth and power-supply equipment (usually a power station or a generator):
- In TN, there is a direct connection between the power supply and the earth and that consumers directly connect to earth through the supply system, usually in the neutral phase N;
- In TT there is a direct connection between the power supply and the earth and that consumers have a direct connection to earth;
- In IT, the power supply is not directly connected to earth and consumers have a direct connection to earth
For safety purposes, you may commonly find protective earths (PE). These exist to connect exposed conductive surface in the consumer to earth – therefore should insulation fail, the potential supply-to-ground leads to a very high current flow triggering a fuse (or circuit-breaker) that disconnects the power supply and prevents harmful electric shocks to human users.
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