EWRB (Electrical Engineering) EXAM PREP THEORY QUESTIONS AND ANSWERS COMPLETE AND RATED A.

EWRB (Electrical Engineering) EXAM PREP THEORY QUESTIONS AND ANSWERS COMPLETE AND RATED A. Explain how the operation of an AC variable speed controller is different to the operation of an electronic soft starter. Correct Answer -- The variable speed controller varies the FREQUENCY and voltage to vary the speed. - The electronic soft start varies voltage on starting to limit the starting CURRENT. Explain the term RAMP TIME as it relates to an AC variable speed controller. Correct Answer -The adjustment that controls the length of time taken for a change in speed to take place. Define extra-low voltage (ELV). Correct Answer -<50V AC or 120V DC. Define low voltage. Correct Answer -50V - 1200V AC or 120V - 1500V DC. Define high voltage. Correct Answer ->1000V AC or 1500V DC. Explain coarse excess-current protection. Correct Answer -When a protection device does NOT interrupt a fault current within 4 hours when a fault current is 1.5 times that of the rated current of the protection device.