These days alternators are designed to have larger air gaps for __________.

Concept & ReasoningModern alternator air-gap design is a compromise involving stability, waveform, excitation requirement and mechanical construction. A relatively larger air gap increases magnetic reluctance, so more field ampere-turns are needed, but it reduces armature-reaction effect and synchronous reactance. Lower Xs raises the steady-state power-angle stability limit Pmax≈3VE/Xs and makes parallel operation more stable. Pole shaping and air-gap distribution are also used to improve the sinusoidal nature of the air-gap flux/mmf. Hence the final key was revised from a single item to 'all of the mentioned'.How to Solve It in the ExamLarge air gap costs excitation but improves stability.Important Exam…