Electrical Engineering is a free introductory textbook to the basics of electrical engineering. See the editorial for more information....


Author: E.E. Kimberly

  Problem Answer
1 A 40-hp, 230-volt shunt-wound motor has an armature-circuit resistance of 0.11 ohm. Calculate the series starting-box resistance necessary to limit the starting current to 1.5 times the rated running current. See Appendix for full-load current.
2 A motor name plate gives the following information: 7.6/9 hp, 115 volts, 56/68 amp, 900/1200 rpm, 100% load, 24 hours 50 C.
(a) What is the rated speed at 9 hp, full load?
(b) What is the significance of the double speed specification?
(c) What is the significance of the double current rating?
(d) What is the significance of the temperature rating?

Last Update: 2011-01-18