Concept explainers
Excluding slip, at what speed (r/min) will an eight-pole, 60-hertz, 240-volt motor run?
Calculate the speed in rpm for of an eight pole,
Answer to Problem 1SQ
The speed in rpm of a squirrel cage induction motor is
Explanation of Solution
Given data:
The number of poles
The frequency
The line voltage
Formula Used:
Write the expression to calculate the speed in rpm of a squirrel cage induction motor.
Calculation:
The total number of poles in the motor is
Substitute
Conclusion:
Thus, the speed in rpm of a squirrel cage induction motor is
Want to see more full solutions like this?
Chapter 31 Solutions
Electric Motor Control
- You are working as a plant electrician. You are told that a large DC motor was returned from the rewind shop and was installed on the previous shift. The motor seemed to operate properly until load was added. The motor then stopped, reversed direction, and began to run at high speed. What is the probable cause of the trouble, and what would you do to correct the problem? Explain your answer.arrow_forwardIf the field current of a shunt wound d.c. motor is halved, what effect will this have on the speed? please answer in typing formatarrow_forward20. What is the effect of applying a lower-than-rated voltage to a fractional-horsepower motor?A. The motor will operate with increased magnetizing current.B. The motor will operate satisfactorily at 95% of the rated voltage.C. The motor will heat up dangerously.arrow_forward
- Question: If a motor driven by PWM using half-bridge operation has a speed of 1422 rpm at a duty cycle of 100% (full forward), what will its speed be at a duty cycle of 63%? Enter your answer to the 2nd nearest decimal place. If rotation direction of the motor is reverse, use negative (-) sign.arrow_forwardWhat is the full-load current of a 230-volt, 3-phase, 125-horsepower synchronous motor when it is operated at an 80% power factor?arrow_forwardQuestions: 1-why does the speed fall slightly when the d.c. shunt motor is loaded?arrow_forward
- If we give a synchronous motor's stator only one volt of power to get it started, what will happen to the motor? Provide a succinct explanation in just one (1) phrase for your answer.arrow_forwardyou are working as a plant electrician. you are told that a large DC motor was returned from the rewind shop and was installed on the previous shift. the motor seemed to operate properly until load was added, the motor then stopped, reversed direction, and began to run at a high speed. what is the probable cause of the trouble, and what would you do to correct the problem?arrow_forwardA 55 hp, 440 V, 400 rpm DC shunt motor draws 107 A when operating at rated conditions. The motor has an armature-circuit resistance of 100 mW and a total field-circuit resistance of 55 W. (vii) What is the motor no-load speed if the no load induced voltage is 440.85V? 390 rpm 395 rpm 400 rpm 405 rpm 410 rpm (viii) What would be the starting line current if the motor was started at full-voltage? 4107 A 4255 A 4392 A 4400 A 4408 A (ix) What is the motor full-voltage starting line current if a 1.9Ω starting resistor is connected in series with the armature? 212 A 220 A 228 A 6 A 6 Aarrow_forward
- How can you determine the current that a direct current motor will draw at start-up?arrow_forwardBy looking at which part of the motor, it can be easily confirmed that a particular motor is a DC motor? (A) Frame (B) Shaft (C) Commutator (D) Stator (E) None of the above.arrow_forwardExplain how does the current will be reduced during the starting of the motor.arrow_forward
- Delmar's Standard Textbook Of ElectricityElectrical EngineeringISBN:9781337900348Author:Stephen L. HermanPublisher:Cengage Learning