Adjustment of Protection Zones in an Impedance Relay for Two Adjacent Transmission Lines
This Demonstration shows how to calculate adjustments for the protection zones in an impedance relay between two adjacent transmission lines.
The "AB transmission line parameters" are the resistance and reactance of the first line. The adjacent BC line is treated analogously.
The "properties of the adjustment" controls are the parameters needed to adjust in the impedance relay. Zone 1 gives the percentage of the AB transmission line that needs protection. Zones 2 and 3 protect the AB and BC lines. Zone 3 is backup protection for zone 2, and zone 2 is backup protection for zone 1.
The "maximum torque angle" control is a parameter for electromechanical relays and represents the angle of adjustment. Every protection adjustment is referenced to this angle.