# 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

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

ANSWER: b. Lags behind the armature current

Q2. The method used to determine Xd and Xq, 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

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

a. Iq is in phase with Ea
b. Id is in phase with Ea
c. Id is at 90 degree to Ea
d. Both (a) & (c)

ANSWER: d. Both (a) & (c)

Q4. The direct axis reactance (Xd) and quadrature axis reactance (Xq) obtained from slip test are

a. Xd = minimum voltage/minimum current , Xq = maximum voltage/maximum current
b. Xd = minimum voltage/maximum current , Xq = maximum voltage/maximum current
c. Xd = maximum voltage/minimum current , Xq = minimum voltage/maximum current
d. Xd = maximum voltage/maximum current , Xq = minimum voltage/minimum current

ANSWER: c. Xd = maximum voltage/minimum current , Xq = minimum voltage/maximum current

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

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

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

ANSWER: d. 4.04 A, 8.04 A

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

a. V2[Xd - Xq / 2XdXq] sin2 δ
b. V2[Xq - Xd / 2Xd Xq]sin2 δ
c. V2[Xd - Xq / XdXq]sin δ
d. V[Xd - Xq / 2Xd Xq]sin2 δ

ANSWER: a. V2[Xd - Xq / 2XdXq] sin2 δ

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