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高等電機機械
學號:M9820202
學生:連崇傑
6.1 THE NAMEPLATE ON 460-V, 50-HP, 60-HZ,
FOUR-POLE INDUCTION MOTOR INDICATES
THAT ITS SPEED AT RATED LOAD IS 1755 R/MIN.
ASSUME THE MOTOR TO BE OPERATING AT
RATED LOAD.
a. What is the slip of the motor?
 b.
What is the frequency of the rotor currents?
 c.
What is the angular velocity of the statorproduced air gap flux wave with respect to the
stator? With respect to the rotor?
 d.
What is the angular velocity of the rotorproduced air gap flux wave with respect to the
stator? With respect to the rotor?

A.
WHAT IS THE SLIP OF THE MOTOR?
B.
WHAT IS THE FREQUENCY OF THE
ROTOR CURRENTS?
C.
WHAT IS THE ANGULAR VELOCITY OF THE
STATOR-PRODUCED AIR GAP FLUX WAVE WITH
RESPECT TO THE STATOR? WITH RESPECT TO
THE ROTOR?
D.
WHAT IS THE ANGULAR VELOCITY OF THE
ROTOR-PRODUCED AIR GAP FLUX WAVE WITH RESPECT
TO THE STATOR? WITH RESPECT TO THE ROTOR?
6.2
STRAY LEAKAGE FIELDS WILL INDUCE
ROTOR-FREQUENCY VOLTAGES IN A PICKUP
COIL MOUNTED ALONG THE SHAFT OF AN
INDUCTION MOTOR. MEASUREMENT OF THE
FREQUENCY OF THESE INDUCED VOLTAGES CAN
BE USED TO DETERMINE THE ROTOR SPEED.
a. What is the rotor speed in r/min of a 50-Hz,
six-pole induction motor if the frequency of the
induced voltage is 0.89 Hz?
 b.
Calculate the frequency of the induced
voltage corresponding to a four-pole, 60-Hz
induction motor operating at a speed of 1740
r/min. What is corresponding slip?

A.
WHAT IS THE ROTOR SPEED IN R/MIN OF
A 50-HZ, SIX-POLE INDUCTION MOTOR IF THE
FREQUENCY OF THE INDUCED VOLTAGE IS
HZ?
0.89
B.
CALCULATE THE FREQUENCY OF THE
INDUCED VOLTAGE CORRESPONDING TO A
FOUR-POLE, 60-HZ INDUCTION MOTOR
OPERATING AT A SPEED OF 1740 R/MIN. WHAT
IS CORRESPONDING SLIP?
6.3 A THREE-PHASE INDUCTION MOTOR RUNS
AT ALMOST 1198 R/MIN AT NO LOAD AND 1112
R/MIN AT FULL LOAD WHEN SUPPLIED FROM A
60-HZ, SOURCE.
a. How many poles does this motor have?
 b. What is the slip in percent at full load?
 c. What is the corresponding frequency of the
rotor currents?
 d. What is the corresponding speed of the rotor
field with respect to the rotor? With respect to
the stator?

A.
HOW MANY POLES DOES THIS MOTOR HAVE?
B.
WHAT IS THE SLIP IN PERCENT AT FULL LOAD?
C. WHAT IS THE CORRESPONDING
FREQUENCY OF THE ROTOR CURRENTS?
D. WHAT IS THE CORRESPONDING SPEED OF
THE ROTOR FIELD WITH RESPECT TO THE
ROTOR? WITH RESPECT TO THE STATOR?