### MCQs of Symmetrical Components

Showing 1 to 10 out of 33 Questions
1.
For measuring positive, negative and zero sequence voltages in a system, the reference is taken as
 (a) Neutral of the system only (b) Ground only (c) For zero sequence neutral and for positive and negative the ground (d) None of the above
2.
A system is said to be effectively grounded if its
 (a) Neutral is grounded directly (b) Ratio of X0 ∕ X1 > 3.0 (c) Ratio of R0 ∕ X1 > 2.0 (d) Ratio of X0 ∕ X1 < 3.0
3.
For complete protection of a 3-phase line
 (a) Three-phase and three-earth fault relays are required (b) Three-phase and two-earth fault relays are required (c) Two-phase and two-earth fault relays are required (d) Two-phase and one-earth fault relays are required
4.
The per unit impedance of a circuit element is 0.15. If the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be
 (a) 0.075 (b) 0.15 (c) 0.3 (d) 0.6
5.
For a star-delta transformer with star-side grounded, the zero sequence current
 (a) Has no path to ground (b) Exists in the lines on the delta side (c) Exists in the lines on the Y side (d) Exists in the lines on both Y and delta sides
6.
Zero sequence currents can flow from a line into a transformer bank if the windings are in
 (a) Grounded star/delta (b) Delta/star (c) Star/grounded star (d) Delta/delta
7.
In an unbalanced 3-phase system, the currents are measured as Ia = zero, Ib = 6∠60° and Ic = 6∠–120°. The zero sequence, positive sequence and negative sequence components will be
 (a) Zero, (3 – j√3), (– 3 + j√3) (b) Zero, ( – 3+ j√3), ( 3 – j√3) (c) Zero, ( – 9+ j 3√3), (9 – j3√3) (d) Zero, ( 9 – j3√3), (– 9 + j3√3)
8.
The impedance per phase of 3-phase transmission line on a base of 100 MVA, 100 kV is 2 pu. The value of this impedance on a base of 400 MVA and 400 kV would be
 (a) 1.5 pu (b) 1.0 pu (c) 0.5 pu (d) 0.25 pu
9.
If the positive, negative and zero sequence reactances of an element of a power system are 0.3, 0.3 and 0.8 respectively, then the element would be a
 (a) Synchronous generator (b) Synchronous motor (c) Static load (d) Transmission line
10.
If a 500 MVA, 11 kV three-phase generator at 50 Hz feeds, through a transfer impedance of (0.0 +j0.605) Ω/phase, an infinite bus also at 11 kV, then the maximum steady state power transfer on the base of 500 MVA and 11 kV is
 (a) 1.0 pu (b) 0.8 pu (c) 0.5 pu (d) 0.4 pu
Showing 1 to 10 out of 33 Questions