Example: A d.c. shunt generator gave the following open-circuit characteristic when driven at 750 r.p.m. Field current 0.5 1.5 2.5 (A) e.m.f. (V) 1- If the machine is run as a shunt generator at 750...

Extracted text: Example: A d.c. shunt generator gave the following open-circuit characteristic when driven at 750 r.p.m. Field current 0.5 1.5 2.5 (A) e.m.f. (V) 1- If the machine is run as a shunt generator at 750 r.p.m., to what voltage will it excite with shunt field resistance equal to 70Q? 50 84 105 120 131 2- What is the critical value of shunt field resistance? 3- What is the critical speed when the shunt field resistance is 702? 4- With shunt field resistance equal to 552. What reduction in speed be made to make the open-circuit voltage equal to 100V? 3