Functionality and Distinctive Features:
- The LV side phasors can be modified with a computer mouse (circle markers) or a keyboard using entry fields on the left;
- The transformer vector group can be modified using the circle switch;
- There is no zero-sequence current on the HV side (the neutral of the HV winding has no connection to earth);
- The voltage ratio of the power transformer is 1;
- Radio buttons allow to set the most frequent short circuit types;
- The value in the “Scale” field is equal to phasor length in a three-phase symmetrical mode;
- The positive rotation is counterclockwise. The angle is 0° if the phase A phasor is pointing towards positive vertical axis;
- A dot serves as decimal separator;
- The interactive model works on a PC with Opera, Chrome, Firefox and Safari browsers
Description:
The phasor diagrams demonstrate the transformation of short-circuit currents from LV to HV side (e.g. 10 kV, 20 kV or 30 kV). The HV side neutral is isolated which is why there are no zero-sequence currents. The positive- and negative-sequence currents are transformed with phase shifts depending on the vector group. This leads to the fact that despite the voltage ratio of 1 the current values are different on both voltage sides. As transformer protection (overcurrent protection) pick-up values are based on HV currents, these current differences have to be taken into account.
Developed by Project RPA