MGVCL Exam Paper (30-07-2021 Shift 1)
The expression for voltage regulation of a short transmission line for lagging power factor is given by: ___, where, 'I' is the line current, 'V_r' is the receiving end voltage, 'R' is the line resistance and 'X' is the line reactance.
For lagging power factor = (IR*cosφ + Ixsinφ)/Vr For leading power factor = (IR*cosφ - Ixsinφ)/Vr Zero voltage regulation occurs on leading power factor only.
Bus Type - Known Parameter - Unknown Parameter Load Bus -P, Q - V, phase angle Generator Bus - P, V (magnitude) - Q, Voltage phase angle Slack Bus Voltage - magnitude and phase angle - P, Q
The magnitude of earth fault current for a given fault position within a winding demands upon the winding connections and method of neutral grounding. Earth fault protection for an electric motor is provide by instantaneous relay having a setting of approximately 30% of motor rated current in the residual circuits of two CTs and with ground wire.