QR: Generator OCC & SCC

• Open-circuit characteristic (OCC), also referred to as the open-circuit saturation curve, of a synchronous machine is a curve of the open-circuit armature terminal voltage (either in volts or in per unit) as a function of the field excitation (current) when the machine is running at synchronous speed.
• Short-circuit characteristic (SCC) of a synchronous machine is a curve of the three-phase short-circuit armature current as a function of the field excitation (current) when the machine is running at synchronous speed.
• The short-circuit ratio (SCR) is defined as the ratio of the field current required for rated voltage on open circuit to the field current required for rated armature current on short circuit.