Slip Test and Reluctance Power of Alternators - - MCQs with answers

Slip Test and Reluctance Power of Alternators - - MCQs with answers

Q1. Depending upon the reluctances offered along the direct axis and quadrature axis, the armature reaction flux will

a. Lead the armature current
b. Lags behind the armature current
c. In phase with the armature current
d. Either (b) or (c)

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Q2. The method used to determine X_d and X_q, the direct and quadrature axis reactance is called

a. Reactance test
b. Blondel’s two reaction theory
c. Slip test
d. All of the above

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Q3. In a salient pole synchronous generator if E_a is the internal induced emf with I_d and I_q be the direct axis and quadrature axis component of armature current, then

a. I_q is in phase with E_a
b. I_d is in phase with E_a
c. I_d is at 90 degree to E_a
d. Both (a) & (c)

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Q4. The direct axis reactance (X_d) and quadrature axis reactance (X_q) obtained from slip test are

a. X_d = minimum voltage/minimum current , X_q = maximum voltage/maximum current
b. X_d = minimum voltage/maximum current , X_q = maximum voltage/maximum current
c. X_d = maximum voltage/minimum current , X_q = minimum voltage/maximum current
d. X_d = maximum voltage/maximum current , X_q = minimum voltage/minimum current

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Q5. In a salient pole synchronous generator direct axis reactance is

a. Greater than quadrature axis reactance
b. Less than quadrature axis reactance
c. Equal to quadrature axis reactance
d. None of the above

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Q6. A synchronous generator has a direct axis and quadrature axis reactances of 0.6 per unit and 0.3 per unit respectively. What will be its total induced emf on open circuit if it is used to supply full load at rated voltage at 0.8 power factor ( Assume rated terminal voltage is equal to 1 pu, full load armature current be 1 pu and armature resistance to be 0).

a. 1.099 pu
b. 1.199 pu
c. 1.488 pu
d. 1.588 pu

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Q7. A 3 phase star connected synchronous generator having direct axis reactance of 8 ohm and quadrature axis reactance of 6 ohm supplies current of 9 A with phase angle of 20 degree lagging at 415 V. Then its direct axis component of armature current and quadrature axis component of armature current are

a. 8.04 A, 4.04 A
b. 4.04 A, 6.84 A
c. 6.84 A, 8.04 A
d. 4.04 A, 8.04 A

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Q8. The reluctance power of a salient pole alternator is given by

a. V²[X_d - X_q / 2X_dX_q] sin2 δ
b. V²[X_q - X_d / 2X_d X_q]sin2 δ
c. V²[X_d - X_q / X_dX_q]sin δ
d. V[X_d - X_q / 2X_d X_q]sin2 δ

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Q9. In case of salient pole alternators, maximum output power can be obtained when power angle (d) is

a. Less than 90 degree
b. Equal to 90 degree
c. Greater than 90 degree
d. None of the above

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