If the excitation of an alternator operating in parallel with another alternator is increased above the normal value of excitation, its ________.

Concept:

• In case of alternators a field rheostat may be used to change the excitation or its field current.
• If alternators are running in parallel, a change in the field current will not change the active power shared significantly but will change the operating power factor.
• With change in the excitation the armature current will change which will change the active power by a small amount.
• The under-excited alternator delivers leading current to the infinite bus bar. It is because the leading current produces an adding m.m.f to increase the under excitation.
• An overexcited alternator operates at lagging power factor and supplies lagging reactive power to an infinite bus bar.
• Therefore, with other alternator is increased above the normal value of excitation, its power factor becomes more lagging.