10. A 3-phase motor rated 50 hp, 220-volts, 75% power factor and 95% efficiency. What is the current at 210-voltsс. 238 Ampsd. 79 Ampsа.144 Ampsb.137 Amps11. A 50-hp, 440-volt, 3-phase, 1750 rpm, SCRIM, how many pair of polesс. 3а.4b. 2d. 112. The required rated voltage applied to a six leads out motor arec. 440-volts and 254-voltsd. All of the aboveа.760-volts and 440-voltsb.220-volts and 127-volts13. The rotating parts of an AC machines isField winding and the coreArmature winding and the corec. Wound Rotor windinga.b.d. All of these

In this question, We need to choose the correct options What is current if voltage V= 210V as…

10. A 3-phase motor rated 50 hp, 220-volts, 75% power factor and 95% efficiency. What is the current at 210-volts 144 Amps 137 Amps c. 238 Amps d. 79 Amps а. b. 11. A 50-hp, 440-volt, 3-phase, 1750 rpm, SCRIM, how many pair of poles

10. A 3-phase motor rated 50 hp, 220-volts, 75% power factor and 95% efficiency. What is the current at 210-volts 144 Amps 137 Amps c. 238 Amps d. 79 Amps а. b. 11. A 50-hp, 440-volt, 3-phase, 1750 rpm, SCRIM, how many pair of poles

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Q2: Correct the wrong statement if any: 1-The series filed of a series de generator is excited by armature current. 2- The developed power in DC generator armature is function to load current. 3-The commercial efficiency of DC generators is relationship between output mechanical power and developed power in armature winding. 4- If the source frequency subjected to primary windings increased, the iron losses also decreased. 5-In transformers short circuit test primary voltage will be greater than secondary voltage.
4. A 2 MVA, 2.3kV, three-phase Wye connected alternator operates at rated kVA at a power factor of 80 %. The dc armature winding resistance between terminals is 0.08-ohm. The field takes 70-A at 125-V from the exciter equipment. Friction and windage loss is 20-kW, iron loss 36-kW and stray power loss are 2.0-kW. Calculate the efficiency of the alternator. Assume the effective armature winding resistance is 120% of the dc resistance.
Determine the efficiency of a 1500kVA, 2300 V, 3 phase, Y-connected alternator, which operatesat rated output with a power factor of 80%. The DC armature resistance at 70°C betweenterminals is 0.08 ohm. The field takes 70 A at 120 V from the exciter equipment. Friction andwindage losses are 15kW, iron loss is 35kW and stray load losses is 1.5kW. Assume the effectivearmature winding resistance is 1.5 times the DC value.
PROBLEMS 3.1. A three-phase, 318.75-kVA, 2300-V alternator has an armature resistance of 0.35 N/phase and a synchronous reactance of 1.2 n/phase. Determine the no-load line-to-line generated voltage and the voltage regulation at (a) Full-load kVA, 0.8 power factor lagging, and rated voltage. (b) Full-load kVA, 0.6 power factor leading, and rated voltage.
Show that an alternator running in parallel on constant-voltage and frequency bus-bars has a natural time period of oscillation. Deduce a formula for the time of one complete oscillation and calculate its value for a 5000-kVA, 3-phase, 10,000-V machine running at 1500 r.p.m. on constant 50-Hz bus-bars. The moment of inertia of the whole moving system is 14,112 kg-m2 and the steady short-circuit is five times the normal full-load value. ANSWER IS [1.33 second]
A three-phase alternator, 2500KVA, and 2400 volts operate at rated kilovolt-Ampere at a power factor of 80%. At 70°C the dc armature resistance between terminals is 0.0852. The current taken by the field winding is 70 Amperes at 130 volts from the exciter equipment. Friction and windage loss is 20KW, Iron loss is 40KW, and the stray power losses are 3KW. Assume that the effective armature winding resistance is 1.2 times the dc value. Calculate the efficiency of the alternator.
A 50-kVA, 550-volt single phase alternator draws a field current 10 A at rated load. With the same field current, the open circuit emf and short-circuit currents are 300V and 150A. The ohmic resistance of the armature between terminals is 0.18ohm. The ratio of effective to ohmic resistance maybe taken as 1.5. Determine the regulation at 0.8 power factor lagging. *Well Explained
A 6 kV , 1000 kVA , 3-ph alternator is delivering full-load at 0.8 lagging. Its reactance is 20% and resistance negligible. By changing the excitation, the e.m.f. is increased by 25% at this load. Calculate the new current and power factor. The machine is connected to infinite bus-bars.
A 50-kW generator has a full-load efficiency of 90.5 percent. Determine the total losses. Ans.: 5,250 watts explain step by step, circuit diagram, principles etc and also write it clearly.
A short shunt compound DC generator supplies a load of 10A at a voltage of 10 volts. If the resistances of Armature, shunt field and series field windings are 0.01 ohm, 1 ohm and 0.00 ohm respectively. c) write down the factors to improve the generated voltage. Generated Voltage is 10.2 V
A 100kW, 230V, shunt generator has an armature resistance and field resistance of 0.050 and 57.50. If the generator operates at rated voltage with SPL at 1.8kW, calculate the following: a) Machines' efficiency of conversion. b) At what load does the generator achieve maximum efficiency c) What is the value of this maximum efficiency?
6. A 2000KVA, 3300V, 3-phase star -connected alternator delivers rated load at a P.F. of 0.85(lagging). The effective resistance between armature winding terminals is 0.12. The field takes 72A at 125V. Friction and windage loss is 18kW and the core losses are 35 kW. Determine the efficiency of the alternator. [Ans. 94.5%]