[amp_mcq option1=”back e.m.f.” option2=”armature current” option3=”power factor” option4=”torque angle” correct=”option1″]<\/p>\n
The correct answer is A. back e.m.f.<\/p>\n
When a synchronous motor is running with normal excitation, the back e.m.f. is equal to the applied voltage. As the load increases, the armature current increases. This causes a decrease in the synchronous reactance, which causes an increase in the current through the field winding. This increase in current through the field winding causes an increase in the magnetic field, which causes an increase in the back e.m.f. The increase in the back e.m.f. causes a decrease in the armature current, which causes a decrease in the current through the field winding, and so on. This process continues until the motor reaches a new steady-state condition with a higher load current and a higher back e.m.f.<\/p>\n
Option B is incorrect because the armature current increases as the load increases.<\/p>\n
Option C is incorrect because the power factor is the ratio of the real power to the apparent power. The real power is the power that is used to do work, and the apparent power is the product of the voltage and the current. The power factor is a measure of how efficiently the motor is converting electrical energy into mechanical energy. The power factor is not affected by the load current.<\/p>\n
Option D is incorrect because the torque angle is the angle between the rotor and the stator magnetic fields. The torque angle is not affected by the load current.<\/p>\n","protected":false},"excerpt":{"rendered":"
[amp_mcq option1=”back e.m.f.” option2=”armature current” option3=”power factor” option4=”torque angle” correct=”option1″]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[965],"tags":[],"class_list":["post-52468","post","type-post","status-publish","format-standard","hentry","category-synchronous-motors","no-featured-image-padding"],"yoast_head":"\n