5. URS Electrician has a 25 kW series generator used in street lighting has an efficiency of 85 8 when operating at rated load. If the stray power loss is 20 % of the full load loss, calculate the efficiency of the generator when delivering a load of 15 kW, assuming that the stray power loss is substantially constant and the other losses vary as the square of the load.

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...
icon
Related questions
Question

Answer number 5

Make solution neatly and accurate

1. A 500 V, 250 kW, long shunt compound generator induces an e.m.f. of 480 V when
running at 1000 r.p.m. no load. On full load the spped of the machine drops to 975
r.p.m. the flux increases by 15% and the terminal voltage rises to 500 V. If the
series and shunt field resistances are 0.02 ohm and 100 ohms respectively,
calculate the armature resistance. Assume a voltage drop of 1V per brush.
2. A 250 V shunt generator has a full load armature current of 40 A, under these
conditions the losses are: FW = 200 watts, shunt field = 100 watts, core = 260
watts, brush contact = 120 watts, armature copper = 400 watts. For operation at
maximum efficiency, when the constant losses are equal to those losses that vary
as the square of the load, calculate the maximum efficiency.
3. A series generator having a combined armature and field resistance of 0.4 ohm us
running at 1000 rpm and delivering 5.5 kW at a terminal voltage of 110 V. If the
speed is raised to 1500 rpm and load adjusted to 10 kW, find the new terminal
voltage. Assume the machine is working on straight line portion of magnetization
characteristics.
4. The dc shunt generator is connected to a load that draws 28,800 watts, given
the armature and shunt field resistance of 0.04 ohm and 48 ohms respectively.
If the power delivered in the armature is 106.3% of the power delivered to the
load. Calculate the generated e.m.f. of the generator.
5. URS Electrician has a 25 kW series generator used in street lighting has an
efficiency of 85 8 when operating at rated load. If the stray power loss is 20 %
of the full load loss, calculate the efficiency of the generator when delivering a
load of 15 kW, assuming that the stray power loss is substantially constant and
the other losses vary as the square of the load.
Transcribed Image Text:1. A 500 V, 250 kW, long shunt compound generator induces an e.m.f. of 480 V when running at 1000 r.p.m. no load. On full load the spped of the machine drops to 975 r.p.m. the flux increases by 15% and the terminal voltage rises to 500 V. If the series and shunt field resistances are 0.02 ohm and 100 ohms respectively, calculate the armature resistance. Assume a voltage drop of 1V per brush. 2. A 250 V shunt generator has a full load armature current of 40 A, under these conditions the losses are: FW = 200 watts, shunt field = 100 watts, core = 260 watts, brush contact = 120 watts, armature copper = 400 watts. For operation at maximum efficiency, when the constant losses are equal to those losses that vary as the square of the load, calculate the maximum efficiency. 3. A series generator having a combined armature and field resistance of 0.4 ohm us running at 1000 rpm and delivering 5.5 kW at a terminal voltage of 110 V. If the speed is raised to 1500 rpm and load adjusted to 10 kW, find the new terminal voltage. Assume the machine is working on straight line portion of magnetization characteristics. 4. The dc shunt generator is connected to a load that draws 28,800 watts, given the armature and shunt field resistance of 0.04 ohm and 48 ohms respectively. If the power delivered in the armature is 106.3% of the power delivered to the load. Calculate the generated e.m.f. of the generator. 5. URS Electrician has a 25 kW series generator used in street lighting has an efficiency of 85 8 when operating at rated load. If the stray power loss is 20 % of the full load loss, calculate the efficiency of the generator when delivering a load of 15 kW, assuming that the stray power loss is substantially constant and the other losses vary as the square of the load.
Expert Solution
steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Knowledge Booster
Maximum power transfer theorem
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.
Recommended textbooks for you
Introductory Circuit Analysis (13th Edition)
Introductory Circuit Analysis (13th Edition)
Electrical Engineering
ISBN:
9780133923605
Author:
Robert L. Boylestad
Publisher:
PEARSON
Delmar's Standard Textbook Of Electricity
Delmar's Standard Textbook Of Electricity
Electrical Engineering
ISBN:
9781337900348
Author:
Stephen L. Herman
Publisher:
Cengage Learning
Programmable Logic Controllers
Programmable Logic Controllers
Electrical Engineering
ISBN:
9780073373843
Author:
Frank D. Petruzella
Publisher:
McGraw-Hill Education
Fundamentals of Electric Circuits
Fundamentals of Electric Circuits
Electrical Engineering
ISBN:
9780078028229
Author:
Charles K Alexander, Matthew Sadiku
Publisher:
McGraw-Hill Education
Electric Circuits. (11th Edition)
Electric Circuits. (11th Edition)
Electrical Engineering
ISBN:
9780134746968
Author:
James W. Nilsson, Susan Riedel
Publisher:
PEARSON
Engineering Electromagnetics
Engineering Electromagnetics
Electrical Engineering
ISBN:
9780078028151
Author:
Hayt, William H. (william Hart), Jr, BUCK, John A.
Publisher:
Mcgraw-hill Education,