I. Problem solving. Solve the following problems. 1. A 36-pole alternator is operated at 20 rps. What frequency is generated? 2. At what speed should a six-pole alternator be driven to develop 40 cycles? 3. An alternator operates at a speed of 176.5 rpm. How many poles does it have if the voltage is generated at 50 cycles? 4. What is the rotor speed (rpm) of a 4-pair generator supplied at 40 hz? 5. What is the rotor speed (in terms of rev per sec) of a ten-pole generator supplied at 60 hz? II. In a generator, how many poles are required in order to acquire maximum speed? Justify or explain your answer.

I. Problem solving. Solve the following problems. 1. A 36-pole alternator is operated at 20 rps. What frequency is generated? 2. At what speed should a six-pole alternator be driven to develop 40 cycles? 3. An alternator operates at a speed of 176.5 rpm. How many poles does it have if the voltage is generated at 50 cycles? 4. What is the rotor speed (rpm) of a 4-pair generator supplied at 40 hz? 5. What is the rotor speed (in terms of rev per sec) of a ten-pole generator supplied at 60 hz? II. In a generator, how many poles are required in order to acquire maximum speed? Justify or explain your answer.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter12: Power System Controls

Section: Chapter Questions

Problem 12.6P

See similar textbooks

Similar questions

An induction motor draws 50 A from a 450 V, three-phase line at a lagging power factor of0.75. Its stator and rotor copper losses are 950 W and 500 W, respectively. Its core lossesare 400 W, the friction and windage losses are 150 W. Determine the following(a) The air-gap power and the developed mechanical power.(b) The shaft output power and the motor efficiency
A four-pair of pole, 50-Hz squirrel-cage induction motor runs on load at a shaft speed of 720 rpm. Calculate the frequency (hertz) of induced current in the rotor.
A 440-V-rms (line-to-line) 60-Hz three-phase wye-connected induction motor draws 16.8 A at a power factor of 80 percent lagging. The stator copper losses are 350 W, the rotor copper loss is 120 W, and the rotational losses are 400 W. Find the power crossing the air gap Pag, the developed power Pdev, the output power Pout and the efficiency.
A three-phase induction motor having a synchronous speed of 1000 revolution per minutedraws 50 kW from a three-phase feeder. The copper losses and iron losses in the stator amount to 5 kW. If the motor runs at 880 r/min.a. The rotor I2R losses b. The mechanical power developed c.The mechanical power delivered to the load, knowing that the windage and friction losses are equal to 2 kW
Consider a machine operating at synchronous speed under steady-state conditions, and let d.c. stator currents flow from the generator having the following magnitudes: ia = 1 ; ib = ic = - 1/2 Find the corresponding id , iq , io . Please use the computer to answer!!
Show your complete solution. Answers must be in 4 decimal places. A 5,000-kVA, 10,000 V, 1500-rpm, 50-Hz alternator runs in parallel with other machines. Its synchronous reactance is 20%. Find for (a) no-load (b) full-load power factor 0.8 lagging, synchronizing power per unit mechanical angle of phase displacement and calculate the synchronizing torque if the mechanical displacement is 0.5 degrees.
A 480V 50Hz Y‐connected six‐pole synchronous generator is rated at 100kVA at 0.8 PF lagging. It has a synchronous reactance of 2.56 Ω/phase and negligible armature resistance. Assume that this generator is connected to a steam turbine capable of supplying up to 113kW. The friction and windage losses are 2kW, and the core losses are 1kW. (a) What is the maximum output power available? (b) Construct the capability curve for this generator considering a max. load angle of 80. (c) Can this generator supply a line current of 200A at 0.6 PF lagging? Why or why not? (d) What is the maximum amount of reactive power this generator can produce? (e) If the generator supplies 40kW of real power, what is the maximum amount of reactive power that can be simultaneously supplied and what is the corresponding field excitation and load angle?
A 2-pole, single-phase alternator driven at 3000rpm require a mechanical input to its rotor of 30kW when it is delivering its full-load output of 30kW. Under this condition the fixed and variable losses are1100W and 2.8kW respectively, and the rotor field winding is supplied from a 110V dc source. Given that the full-load efficiency is 87%, determine. the frequency generated, the input driving torque on full-load and the rotor field current
Calculate for full-load and unity p.f., the natural period of oscillation of a 50-Hz, 10,000-kVA, 11-kV alternator driven at 1500 r.p.m. and connected to an infinite bus-bar. The steady short-circuit current is four times the full-load current and the moment of inertia of the rotating mass is 17,000 kg-m2. ANSWER IS [1.148 second]
If the no load speed of a motor is 1000 rpm and it decelerates by 30 rpm at full load, find the speed regulation.
3. A group of induction motors rated 2200-V, 3-phase, 60 Hz delivers a total of 600 HP and is operating at an average power factor of 0.8 lagging. If half of this total load is replaced by a group of synchronous motors operating at 0.8 leading, determine the difference in the line current? Assume all motors operate at an average efficiency of 90%.
A 3-phase induction motor having a synchronous speed of 1200 rpm draws 70kW from a 3-phase feeder.The copper losses and iron losses in the stator amount to 4kW.Friction and windage losses amount to 2kW.If the motor runs at 1170 rpm, determine the a. active power transmitted to the rotorb. rotor copper lossesc. mechanical power developedd. the mechanical power delivered to the loade. efficiency of the motor.