SYNCHRONOUS MACHINES Power and Torque Characteristics SEE 3433 MESIN ELEKTRIK SYNCHRONOUS MACHINES Power and Torque Characteristics

Power and Torque Characteristics + Ef  Ia jXs Ra Vt Let Vt = Vt 0o Ef = Ef o This gives : Complex power is given by: S = Vt Ia* = P + jQ Active power Reactive power

Power and Torque Characteristics P = Active power = Q = Reactive power = S = Vt Ia* = P + jQ If |Z| = Xs hence  = 90o

Power and Torque Characteristics P, T Pmax 90o Tmax 

Power and Torque Characteristics The machine will loose synchronism when the power angle,  greater than 90o P, T  90o Pmax Tmax e.g. generator operation. As prime mover power increased, generator need to produce torque to ‘pull’ machine to synchronism – limit when =90o The Tmax or Pmax can be increased by increasing the field excitation