## 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)

View Answer / Hide Answer**ANSWER: b. Lags behind the armature current **

**Q2. The method used to determine X**_{d} and X_{q}, the direct and quadrature axis reactance is calleda. Reactance test

b. Blondelâ€™s two reaction theory

c. Slip test

d. All of the above

View Answer / Hide Answer**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, thena. 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)

View Answer / Hide Answer**ANSWER: d. Both (a) & (c) **

**Q4. The direct axis reactance (X**_{d}) and quadrature axis reactance (X_{q}) obtained from slip test area. 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

View Answer / Hide Answer**ANSWER: c. X**_{d} = maximum voltage/minimum current , X_{q} = 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

View Answer / Hide Answer**ANSWER: a. Greater than quadrature axis reactance **

**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

View Answer / Hide Answer**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

View Answer / Hide Answer**ANSWER: d. 4.04 A, 8.04 A **

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

^{2}[X

_{d} - X

_{q} / 2X

_{d}X

_{q}] sin2 δ

b. V

^{2}[X

_{q} - X

_{d} / 2X

_{d} X

_{q}]sin2 δ

c. V

^{2}[X

_{d} - X

_{q} / X

_{d}X

_{q}]sin δ

d. V[X

_{d} - X

_{q} / 2X

_{d} X

_{q}]sin2 δ

View Answer / Hide Answer**ANSWER: a. V**^{2}[X_{d} - X_{q} / 2X_{d}X_{q}] 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

View Answer / Hide Answer**ANSWER: a. Less than 90 degree **