Question 263Electricity/Electronics - Assistant Engineer70% to pass
Assuming that the 3-phase power source has a phase sequence of A-B-C and that the motor is connected as shown in figure "A", if the motor has a clockwise (CW) rotation, what statement is true concerning the motors connected as shown in the other figures? Illustration EL-0156
AI Explanation
The correct answer is D) Motors "B" and "D" would have a counter-clockwise (CCW) rotation and motor "C" would have a clockwise (CW) rotation.
The reasoning is that with the given 3-phase power source and A-B-C phase sequence, the motor connection in figure "A" results in a clockwise (CW) rotation. However, reversing the connection of any two phases of the 3-phase supply will reverse the rotation direction. In figures "B" and "D", the connections of two phases are reversed compared to figure "A", resulting in a counter-clockwise (CCW) rotation. In figure "C", only one phase connection is reversed, leading to a clockwise (CW) rotation.
The other options are incorrect because they do not accurately describe the rotation direction of the motors in the different figures based on the given phase sequence and motor connections.
Related Questions
#261 Which of the listed motors will operate at the highest RPM, assuming that each operates at the same frequency? #262 The torque-speed and current-speed curves for a three-phase induction motor with a squirrel cage rotor are shown in figures "A" and "B" of the illustration. Which of the following statements is true concerning the depicted curves? Illustration EL-0056 #264 According to 46 CFR, Subchapter J (Electrical Engineering), in response to a loss of normal power or a simulated test, when will the emergency loads automatically be transferred to the emergency diesel-generator? #265 Emergency generators are required to automatically start upon a loss of normal supply voltage, according to 46 CFR, Subchapter J (Electrical Engineering). In conducting a test of the emergency generator automatic transfer of load function, if the normal system supply voltage is 450 VAC, to what value would the emergency generator output voltage have to rise to trigger the automatic transfer of emergency loads to the emergency generator? #266 According to 46 CFR, Subchapter J (Electrical Engineering), which of the following starting aids is the ONLY method allowed to ease the starting of emergency diesel-generator engines?