A 7.5-hp 120-V series de motor has an armature resistance of 0.2 $2 and a series field resistance of 0.16 22. At full load, the current input is 58 A, and the rated speed is 1050 r/min. Its magnetization curve is shown in Figure. The core losses are 200 W, and the mechanical losses are 240 W at full load. Assume that the mechanical losses vary as the cube of the speed of the motor and that the core losses are constant. Internal generated voltage E₁, V 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 10 20 Speed 1200 r/min 30 40 Series field current, A 50 60 70 (a) What is the efficiency of the motor at full load? (b) What are the speed and efficiency of the motor if it is operating at an armature current of 35 A?

A 7.5-hp 120-V series de motor has an armature resistance of 0.2 $2 and a series field resistance of 0.16 22. At full load, the current input is 58 A, and the rated speed is 1050 r/min. Its magnetization curve is shown in Figure. The core losses are 200 W, and the mechanical losses are 240 W at full load. Assume that the mechanical losses vary as the cube of the speed of the motor and that the core losses are constant. Internal generated voltage E₁, V 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 10 20 Speed 1200 r/min 30 40 Series field current, A 50 60 70 (a) What is the efficiency of the motor at full load? (b) What are the speed and efficiency of the motor if it is operating at an armature current of 35 A?

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter32: Three-phase Motors

Section: Chapter Questions

Problem 6RQ: Name three factors that determine the torque produced by an induction motor.

See similar textbooks

Related questions

Q: Question 3: Answer the following question below: a. Consider a permanent-magnet de motor with the…

A: Note: We are authorized to answer one question at a time since you have not mentioned which question…

Q: A four-pole 60-Hz 240-V-rms induction motor operates at 1750 rpm and produces 2 hp of output power.…

A: Given: A induction motor has Poles, P=4 Frequency, f=60 Hz Rated voltage, Vs=240 V Motor speed,…

Q: A 250 V DC shunt generator has a constant loss of 1250 W. Find the load current for maximum…

A: Solution: Shunt generator; V=250 v, Constant loss =1250 W, Find the load current for maximum…

Q: Running at 1200 rpm from a 280-V source, a series-connected dc motor draws an armature current of 25…

A: Given data: The value of armature current is: 25 A The field resistance is: 0.2 Ω The expression for…

Q: A 230V DC series motor operates at its full load current and speed of 22A and 750 revolutions per…

A: Types of DC Motor Seperetely excited motor Series Motor Shunt Motor Compound Motor Differential…

Q: A 250V series motor runs at 500 rpm at rated load current of 75 A. The armature circuit has a…

A: It is given that: V=250 VN1=500 rpmIL1=Ia1=75 ARa+Rse=0.2 Ωϕ α Ia

Q: Q2- A 240V, series DC motor has armature and field resistances of 0.32 and 0.4 2 respectively. Its…

A: In this question, we need to determine the speed and current at the reduced torque i.e 60%.It's DC…

Q: Sketch the torque versus speed characteristic for a series-connected dc motor.

A: The circuit diagram of the DC series motor can be drawn as Thus for constant power motor : Ns α 1Γ…

Q: A 50-kW 440-V 50-Hz two-pole induction motor has a slip of 6 percent when operating at full-load…

A: It is given that:To find:

Concept explainers

Speed control of motor

Speed control by DC motor-speed controller is required to realize variable speed drive. Whenever a motor drives a particular load, it is called drive, and variable speed drive refers to a load requiring variable speed. All this is obtained by a DC motor speed controller.

Question

A 7.5-hp 120-V series de motor has an armature resistance of 0.2 2 and a series field resistance of 0.16
2. At full load, the current input is 58 A, and the rated speed is 1050 r/min. Its magnetization curve is
shown in Figure. The core losses are 200 W, and the mechanical losses are 240 W at full load.
Assume that the mechanical losses vary as the cube of the speed of the motor and that the core losses are
constant.
Internal generated voltage EA, V
160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
10
20
Speed 1200 r/min
30
40
Series field current, A
50
60
70
(a) What is the efficiency of the motor at full load?
(b) What are the speed and efficiency of the motor if it is operating at an armature current of 35 A?

Expert Solution

This question has been solved!

Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.

SEE SOLUTION Check out a sample Q&A here

INTRODUCTION

Solution Part (a)

Part (b)

Step 4

Step by step

Solved in 4 steps

SEE SOLUTION Check out a sample Q&A here

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

Q4/B/ What are the principal characteristics of a series DC motor? What are its uses? Core Mc
200 +21. If maximum torque of an induction motor is kg-m at a slip of 12%, the torque at 6% slip would be...... kg-m. 1 (a) 100 (b) 160 (c) 50 (d) 40 B, 1993)
A 240 V series motor develops a torque of 120 Nm at a speed of 900 rpm. The armature winding resistance is 0.20 and the series field winding resistance is 0.1 Q. For a constant load torque find the new speed of the motor when a diverter resistance of 0.1 Q is placed across the series field winding.
A 250 V series motor has an armature resistance of 0.2 ohm and a series-fieldresistance of 0.18 ohm. If the speed is 6oo RPM when the current is 32 amps.What will be the motor speed when the load is reduced so that the current is18 amps, under which condition the percent flux change is 50 % of the percentcurrent change.
pole. 50-Hz. 3-ϕ induction motor has a full-load speed of 950 rpm. At half load its speed would be ..... rpm a) 475 b) 500 c) 975 d)1000
1. The operation of Commutator in DC Motor is * O a) to convert dc to ac O b) to convert ac to dc O c) to convert fixed dc to variable dc O reverse the current direction in the rotating windings each half turn
A value of magnetizing current in a 3-phase induction motor * gives power factor smaller .. larger smaller. .poor large . better O large...poor O
2. A 2-pole, 50 Hz induction motor supplies 15 kW to a load at a speed of 2950 rpm. a. What is the motor's slip? b. What is the induced torque in the motor in N-m under these conditions? c. What will be the operating speed of the motor be if its torque is doubled? d. How much power will be supplied by the motor when the torque is doubled?
A 220 V DC series motor runs drawing a current of 30 A from the supply. Armature and field circuit resistances are 0.4 and 0.1 respectively. The load torque varies as the square of the speed. The flux in the motor may be taken as being proportional to the armature current. To reduce the speed of the motor by 50% the resistance in ohms that should be added in series with the armature is
A 240-volt series motor has an armature resistance of 0.42 ohm and a series-field resistance of 0.18 ohm. If the speed is 500 rpm when the current is 36 A, what will be the motor speed when the load reduces the line current to 21 A? (Assume a 3-volt brush drop and that of the flux is proportional to the current.). Ans.: 1435 rpm show diagram and step by step process
Please question 5 solution
Please question 4