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1) In what direction does the phasor get rotated if it is multiplied by the operator ‘a’? a. Anti clockwise b. Clockwise c. Gets rotated by 90° in the clockwise direction d. Gets rotated by 90° in the anticlockwise direction
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2) The positive sequence current is always equal to ______________. a. Always zero b. 1/3 of the negative sequence current c. Negative sequence current d. 3 times the negative sequence current
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3) What is the value of the zero sequence current? a. 3 times the current in the neutral wire b. 1 / 3 times the current in the neutral wire c. √3 times the current in the neutral wire d. Equal to the current in the neutral wire
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4) In the manufacture of transformers, ANSI prescribes certain standards. What is this standard? a. High voltage side should lead the low voltage side by 30° with Y - Δ or Y - Δ connections. b. High voltage side should lead the low voltage side by 60° with Y - Δ or Y - Δ connections. c. High voltage side should lag the low voltage side by 30° with Y - Δ or Y - Δ connections. d. High voltage side should lag the low voltage side by 60° with Y - Δ or Y - Δ connections.
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5) For Y - Δ and Δ - Y transformers, the phase shift between the transformer windings is equal to “ n * 30° “. What does ‘n’ represent in the equation? a. Number of windings b. Number of turns c. Turns ratio d. Hour number
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6) Phase shift of symmetrical components happens in which among the following? a. Delta - delta b. Star – delta c. Delta – star d. Both (b) and (c) e. All of these
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7) What is the value of negative sequence impedance? a. 1 b. Z c. Same as positive sequence d. ∞
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8) Zero sequence currents cannot flow in which of the following connections? a. Delta b. Star c. Star – star d. Both (b) and (c) e. All of these
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9) What happens to the zero sequence currents, if the neutral in the Y connection is absent? a. Minimum b. Zero c. Maximum d. ∞
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10) What are the types of unsymmetrical faults? a. Single line to ground fault b. Double line to ground fault c. Line to line fault d. All of these e. None of these
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