Rating must be same

Phase sequence must be same

Rotor impedance must be same

Stator impedance must be same

1000 rpm

1500 rpm

3000 rpm

4500 rpm

Terminal voltages are equal

Voltages and frequencies are equal

Voltages and phase sequence are equal

Both the alternators receive same frequency

Field resistance

Armature reaction

Inductive reactance

Armature resistance

Prevents heating

Reduces copper loss

Reduces windage loss

Prevents the hunting effect