Earth Is the Lords
5th Edition
ISBN: 9781121660069
Author: Caldwell, Taylor
Publisher: MCG/CREATE
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 3, Problem 3.11P
In later years, motors improved and could be run directly from a 60 Hz power supply. As a result, 25 Hz power systems shrank and disappeared. However, there were many perfectly good working 25 Hz motors in factories around the country that owners were not ready to discard. To keep them running, some users created their own 25 Hz power in the plant using motor-generator sets. A motor-generator set consists of two machines connected on a common shaft, one acting as a motor and the other acting as a generator. If the two machines have different numbers of poles but exactly the same shaft speed, then the electrical frequency of the two machines will be different due to Equation (3-34). What combination of poles on the two machines could convert 60 Hz power to 25 Hz power?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
An induction motor load of 1500 watts with a power factor of 0.75 is combined with a 500 volt amperes of synchronous motor with a power factor of 0.65 leading. What kvar of capacitors is required to correct the overall power factor of the two groups of motors to 0.95 lagging? What percent reduction in volt amperes results?
) A 430V, 3-phase Induction motor has output of 36HP and operates at power factor of 0.8 lagging with an efficiency of 84%. Calculate the reading on each of the two wattmeter connected to measure the input.
The value of P1 is =
The value of P2 is =
C2 (ii) Three inductive coils each of inductance 58 mH are connected in star to a 3 phase 215V, 50 Hz supply. Calculate the inductance of each coil, which when connected in delta to the same supply will take the same line current.
Reactance Xc is =
The Inductance L =
A three-phase, star-connected, 7460 kW, 6000V, 50 Hz synchronous motor has a power factor of 0.8, while its efficiency is 92% when feeding a load upstream. This motor has an armature resistance of 0.5 Ω and a synchronous reactance of 4.2 Ω. The stator windings are connected to an infinitely powerful network. A mechanical load equal to 75% of the rated load is connected to the shaft of the motor. According to this;
a)Enter the amplitude value of the current passing through the phase windings of the motor.
b) Calculate the pole wheel voltage induced in the motor
c) Calculate the load angle.
ç) Enter the value of the internal phase angle.
Chapter 3 Solutions
Earth Is the Lords
Ch. 3 - What is the principal difference between a...Ch. 3 - Prob. 3.2QCh. 3 - Prob. 3.3QCh. 3 - What is the equation for the induced torque in an...Ch. 3 - The simple loop rotating in a uniform magnetic...Ch. 3 - Prob. 3.2PCh. 3 - The first ac power system in the United States ran...Ch. 3 - A three-phase, Y-connected, four-pole winding is...Ch. 3 - A three-phase, -connected, six-pole winding is...Ch. 3 - A three-phase, Y-connected, 60 Hz, two-pole...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, electrical-engineering and related others by exploring similar questions and additional content below.Similar questions
- An industrial plant consisting primarily of induction motor loads absorbs 500 kW at 0.6 power factor lagging. (a) Compute the required kVA rating of a shunt capacitor to improve the power factor to 0.9 lagging. (b) Calculate the resulting power factor if a synchronous motor rated at 500 hp with 90 efficiency operating at rated load and at unity power factor is added to the plant instead of the capacitor. Assume constant voltage (1hp=0.746kW).arrow_forwardInduction motors and welding transformers require magnetizing current, which causes a. lagging power factor. b. leading power factor. c. unity power factor. d. zero power factor.arrow_forwardThe name plate of single phase induction motor has following data output 373W,230V, frequency 50Hz. Input current 2.9A and power factor is 0.71. Speed 1420 rpm What is efficiency of motor.arrow_forward
- A 400V, 50Hz 30hp three-phase induction motor is drawing current at power factor 0.8 lagging. The stator and rotor copper losses are 1.5kW and 900W respectively. The friction and windage losses are 1050W and the core losses are 1200W . Find the air-gap power of the motor.arrow_forwardThe rotor of a 3-phase, 60 Hz, 4-pole induction motor takes 118 kW at 3Hz. The motor has stator copped loss of 2.95 kW, a mechanical loss of 2kW and a stator core loss of 1.7 kW. Solve for the motor efficiencyarrow_forwardA 3-phase, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill between the slip-rings on open-circuit. Calculate the current and power factor at standstill when the rotor winding is joined to a star-connected external circuit, each phase of which has a resistance of 10 Q and an inductance of 0.04 H. The resistance per phase of the rotor winding is 0.2 N and its inductance is 0.04 H. 4. Also, calculate the current and power factor when the slip-rings are short-circuited and the motor is running with a slip of 5 per cent. Assume the flux to remain constant. Identify it`s given and solve itarrow_forward
- An electromechanical AC/DC conversion system consists of a 460V, 175hp, four-pole, 60Hz,Y connected induction motor mechanically coupled to a separately excited, 430V, 130kW,four-pole DC generator. The parameters of the motor and the generator are given below: Induction Motor: R1=0.058Ω; R2=0.037Ω DC Generator:Ra=0.15Ω; Pf,wi=2kW X1=0.32Ω; Xm=9.24Ω; X2=0.386ΩPf,wi=1kW Test measurements show that the field winding current of the DC generator has to beadjusted to 20A when the machine operates at full load at 1800rpm and rated voltage.If the induction machine, supplied from the 460V (line to line) source, operates at 4% slipwhile driving the DC generator, calculate:a) The induction motor stator current, input power, and output torque (mechanical torqueon the motor shaft).b) The DC generator load current, and the output power delivered to the load, assumingthat the field winding current is 20A. Calculate the efficiency of the whole systemarrow_forwardA 500V, 60Hz, single phase synchronous motor develops 20hpand is operating at a pf of 0.8 lagging. Effective resistance ofarmature is I ohm. Iron an friction losses amount to 500W.Determine power drawn by the motor from the source.arrow_forwardA three-phase star connected six-pole induction motor has the following parameters. R 0.294 ; R =0.144 N; X₁ = 0.503 N; X₂ = 0.209 N; X = 13.25 2. The slip of the motor is 2 per cent. The stator input impedance of the motor is,arrow_forward
- Q25)ii) When the speed difference will be maximum in three phase induction motor. Justify your answerarrow_forward4 DECIMAL PLACES : 1. A single-phase motor has stator windings in space quadrature and is supplied with a single-phase voltage of 200 V at 50 Hz. The standstill impedance of the main winding is (5.2 + j10.1) and of the auxiliary winding is (19.7 + j14.2). Find the value of capacitance to be inserted inthe auxiliary winding for maximum starting torque.arrow_forwardA 2-pole wound rotor three-phase asynchronous motor is connected to a three-phase 380 V compound voltage network. The stator and rotor are star connected. The transformation ratio of voltages coincides with that of currents and is equal to 2.5. The parameters of the equivalent circuit of the motor per phase are: R1 = 0.5 [Ohm], X1 = 1.5 [Ohm], R2 = 0.625 [Ohm], X2 = 1.25 [Ohm], RFE = 360 [Ohm], XM = 40 [ Ohm]. The mechanical losses are 250 [W]. If the slip at full load is 5 [%], it is ordered using the approximate equivalent circuit of the motor: a) Stator current, rotor current, magnetizing current. b) Loss of iron, active and reactive power absorbed by the network motor. c) Internal power and mechanical power in the shaft.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Power System Analysis and Design (MindTap Course ...Electrical EngineeringISBN:9781305632134Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. SarmaPublisher:Cengage Learning
Electricity for Refrigeration, Heating, and Air C...Mechanical EngineeringISBN:9781337399128Author:Russell E. SmithPublisher:Cengage Learning
Power System Analysis and Design (MindTap Course ...
Electrical Engineering
ISBN:9781305632134
Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma
Publisher:Cengage Learning
Electricity for Refrigeration, Heating, and Air C...
Mechanical Engineering
ISBN:9781337399128
Author:Russell E. Smith
Publisher:Cengage Learning
How Electric Motors Work - 3 phase AC induction motors ac motor; Author: The Engineering Mindset;https://www.youtube.com/watch?v=59HBoIXzX_c;License: Standard Youtube License