Electrical field pattern of high and low voltage substation.

Field pattern of high and low voltage

The PPC provides in high consumption high voltage (common 20.000 volts). This interest PPC in terms of maintenance of substation transformers that do not belong to it, and the consumer due to a lower current value .

The provider brings only three conductors, one for each phase.

The transformers are connected in triangle at the input of 20,000 volts and star on output of 400 volts. The hub of the star is the neutral.

In the secondary of the transformer and before the main switch low voltage capacitors are permanently connected , always in triangle, which correct the cosφ due to the transformer . The value of the capacitors shown in units of reactive power and not farad .

In example drawing we have two transformers and are connected in parallel.
In parallel connection necessary transformers should have exactly the same features, otherwise there is a problem due to asymmetry .

Usually these customers have generator that produces electricity for critical loads need and connects them by relays . The neutral of the generator and the three phases is connected with  relay  .

If the high voltage supply switch " down " from human handling, automatically and mechanically by the same switch , the consumption connected to ground for protection. There are special gloves for this operation that resist the voltage and have an expiry date