Single Phase Grounding Transformer
The grounding transformer is typically connected between the star center of a three-phase generator and the ground.
As can be distinguished from the diagram, it is the primary which, connected in series to the star center of the generator and the ground, forms an impedance that can be more or less high depending on the load that will be associated with the secondary circuit of the transformer.
In this way, it is possible to limit the fault current by inserting a resistor with a "small" ohmic value and at low voltage. A product with these characteristics is much cheaper and more manageable than the MV equivalent in terms of power.
Depending on the destination of the transformer, it is possible to connect a resistor or a reactance to the secondary, depending on the type of load, the behavior of the transformer during the fault will also vary.
The benefit therefore lies in being able to limit fault currents by giving the necessary time to the protections to intervene. Voltage transients are also attenuated by means of a system that can withstand a high number of faults without losing efficiency.
Grounding transformers are characterized by the following data:
- Continuous and fault nominal apparent power
- Time to failure
- Primary Voltage Rating
- Secondary Voltage Rating
- Insulation class
- Temperature class
- Operating ambient temperature