Q6Electrical Machines II
Question
2 marks
What information can be obtained from a V curve?
Answer
The V-curve reveals the required field excitation for a synchronous motor to operate at unity, lagging, or leading power factor.
A V-curve plots the stator armature current against the DC field excitation current for a synchronous machine at a constant load.
It provides vital operational information, showing exactly how the machine's power factor changes with excitation. The lowest point on the "V" indicates operation at unity power factor. Excitation below this point causes lagging power factor, while excitation above this point causes leading power factor (useful for power factor correction).