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
Symmetrical breaking current is the moment when fault occurs maximum fault current is observed and decays with respect to time. Symmetrical breaking current = RMS value of ac component of short circuit current at the instant of separation of the contacts. Symmetrical breaking capacity is less than asymmetrical breaking capacity.
Buchholz relay is used for protecting transformer against incipient or internal faults. Buchholz relay is a gas-actuated relay installed in oil immersed transformers for protection against all kinds of faults.
EXAMIANS