TN-C Network • The generator star point is connected to Neutral and to Earth. • The phases and a combined Neutral-Earth are distributed. • The consumer splits up the incoming Neutral and Earth (MEN link). • The consumer uses the supplied phases and the newly created Neutral and Earth.
TN-C-S Network • The generator star point is connected to Neutral and to Earth. • The phases and a combined Neutral-Earth are distributed. • The consumer splits up the incoming Neutral and Earth (MEN link). • The consumer connects to Earth to earth stake. • The consumer uses the supplied phases and the newly created Neutral and Earth.
TT network • The generator star point is connected to Neutral and Earth. • The phases and Neutral are distributed. • The consumer uses the supplied phases and Neutral. • The consumer creates a local Earth connection.
IT network • The generator star point is not connected to Neutral and Earth. • The phases are distributed. • The consumer uses the supplied phases. • The consumer creates a local Earth connection.
5.3 System current VA and Watt
To be able to correctly calculate fuses, wiring size or inverter size you will need to know the currents that can run through an AC circuit. To be able to correctly calculate current there is one aspect of AC power that will need to be explained, namely Watt and VA. AC power is alternating power. Both the voltage and the current are a sine wave. Certain loads can cause the current sine wave to lag behind the voltage sinewave. Watt is the real power drawn by the equipment. The Watt rating determines the actual power purchased from the utility company, the diesel consumed by a generator or the heat loading generated by the equipment. VA is the “apparent power” and is the product of the voltage times the current drawn by the equipment. The VA rating is used for sizing wiring, circuit breakers, inverters or generators.
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