Question

3. An electric motor draws 2238 W and 12 A when operating on a 240 V source. Determine the (a) Power factor of the motor. (b) Apparent power input to motor. (c) True power input to motor. (d) Horsepower output of the motor if it is 75% efficient. 4 The follwing s found on the nameplate of a motor. 3 hp 60 Hz 1 phase 120/240 V 34/17 A 1,740 RPM irthe power factor of the motor is 0.30, what is the power Input to the mor a 247 load? (b) What is the efficiency of the motor at full load? (c) How much does it cost to operate the motor at full load for 100 hours at 50.06 per kWh? s (a) How many foot-pounds of work must be done in filling a 30,000 gallon tank with water from a well in which the water level is 159 ft below the tank? (1 ga 8/, lb). (b) What horsepower is needed to fill the tank ciency? in two hours assuming 100% effi- (c) If the motor and pump combination is 45% efficient, what size of motor is needed? 6. What size of copper wire cable (THW insulation) is needed for the following mo- tor if located 30 m from the service entrance 3 hp 240 V single-phase 7. What size of wire is needed for a S hp single-phase motor located 12 m from the source? Assume aluminum, UF insulation, and cable underground. 8. What size copper wire would be needed for a branch circuit to a 0.75 hp 240 V 9 What size of copper wire would be needed for a branch circuit to a 75 hp 240 V 10. What size overcurrent protection would be needed for the branch circuit in prob- motor located 75 feet from the service entrance? motor on a vacuum pump located 25 ft from the service entrance? lem 9 if (a) Time-delay fuses are used? (b) Non-time-delay fuses are used? (c) Circuit breakers are used? 11. Given the following table of results from a motor dynamometer test of a single phase motor, calculate horsepower, power factor, and efficiency for each foad level. Then plot, as a function of horsepower output, the following (a) Efficiency (b) Power Factor (c) Current (d) Motor speed Assume electrical instrumentation as shown in Fig 825 and that the Prons brake used has a lever arm of 025 n

Answer 1

given tha clectsic motor drauos 2238 d anca RuDV Ca) power bactoy poues C6) apparantr powex input. to motor opparant poer snea.ctue powey - Vr sino GAR ue power measured in wats d Horse power of m Horse Powel = 1678-6