Legal Metrology • Electrical Engineering Paper-II
For a stable system
A)
gain margin and phase margin both are negative
B)
gain margin is positive and phase margin is negative
C)
gain margin is negative and phase margin is positive
D)
gain margin and phase margin both are positive
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'gain margin and phase margin both are positive' (Option D).
Legal Metrology • Electrical Engineering Paper-II
The greater the diversity factor of a power station
A)
Indicates higher plant capacity
B)
higher is the cost of generation of power
C)
lesser is the cost of generation of power
D)
none of the above
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'none of the above' (Option D).
Legal Metrology • Electrical Engineering Paper-II
The transfer function of a P-I controller is
A)
K + K_i/s
B)
K + K_i*s
C)
K_i/s + K_d*s
D)
K_i*s - K
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'K + K_i/s' (Option A).
Legal Metrology • Electrical Engineering Paper-II
The frequency at which the magnitude of the Bode plot crosses 0dB axis is termed as
A)
natural frequency
B)
phase crossover frequency
C)
corner frequency
D)
gain crossover frequency
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'gain crossover frequency' (Option D).
Legal Metrology • Electrical Engineering Paper-II
If field resistance of a d.c shunt generator is increased beyond its critical value, the generator
A)
will not build up
B)
output voltage will exceed its name plate rating
C)
may burn out if loaded to its name plate rating
D)
power output may exceed its name plate rating
If field resistance exceeds critical resistance, the shunt generator cannot build up voltage.
Legal Metrology • Electrical Engineering Paper-II
The slight curvature at the lower end of the O.C.C of a self-excited d.c generator is due to
A)
magnetic inertia
B)
high field circuit resistance
C)
high armature speed
D)
residual pole flux
The lower-end curvature of a self-excited generator’s OCC originates from residual magnetism/flux.
Legal Metrology • Electrical Engineering Paper-II
In a transmission line, the generalised circuit constants of the transmission line AD-BC is equal to
A)
zero
B)
1
C)
-1
D)
0.5
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'zero' (Option A).
Legal Metrology • Electrical Engineering Paper-II
Ferranti effect on long overhead lines is expressed when it is
A)
lightly loaded
B)
fully loaded at unity p.f
C)
fully loaded at 0.8 p.f lag
D)
none of the above
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'fully loaded at 0.8 p.f lag' (Option C).
Legal Metrology • Electrical Engineering Paper-II
Given the transfer function G(s) = 1 / (s^2 + 13.2s + 121) of a system. Which of the following characteristics does it have?
A)
overdamped and settling time 1.1s
B)
critically damped and settling time 0.8s
C)
under-damped and settling time 0.6s
D)
under-damped and settling time 0.707s
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'overdamped and settling time 1.1s' (Option A).
Legal Metrology • Electrical Engineering Paper-II
Of the following statements concerning parallel operation of transformers, the one which is not correct is
A)
transformers must have equal KVA ratings
B)
transformers must have equal voltage ratings
C)
transformers must have same ratio of transformation
D)
transformers must be operated at the same frequency
Parallel transformers need compatible ratings, voltage ratios, impedance, polarity, and frequency; identical kVA rating is not mandatory, so A is not correct.
Legal Metrology • Electrical Engineering Paper-II
If the poles of a system lie on the imaginary axis, the system will be
A)
conditionally stable
B)
stable
C)
unstable
D)
marginally stable
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'unstable' (Option C).
Legal Metrology • Electrical Engineering Paper-II
In a force-voltage analogy, the mass M, spring constant K and friction constant B are equivalent to which of the following corresponding electrical quantities (in order) as
A)
R, C, L
B)
R, 1/L, C
C)
L, 1/C, R
D)
1/C, L, R
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is 'R, C, L' (Option A).
Legal Metrology • Electrical Engineering Paper-II
The value of A, B, C and D constants for a short transmission line are respectively
A)
0, 1, 1 and 1
B)
Z, 0, 1 and 1
C)
1, Z, 0 and 1
D)
1, 1, Z and 0
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is '1, 1, Z and 0' (Option D).
Legal Metrology • Electrical Engineering Paper-II
Consider the following quantities: 1. Real power, 2. Reactive power, 3. Power factor, 4. Input current, 5. Bus voltage magnitude, 6. Bus voltage phase angle. For the purpose of the load flow studies of a power system, each bus or node is associated with which one of the combinations of the above four quantities?
A)
1, 3, 4 and 5
B)
1, 2, 3 and 4
C)
1, 2, 5 and 6
D)
2, 3, 5 and 6
Load-flow buses are characterized by combinations of P, Q, |V| and angle δ; the listed combination is 1,2,5,6.
Legal Metrology • Electrical Engineering Paper-II
Which of the following relay structure produce torque more efficiently?
A)
induction cup structure
B)
watt-hour meter structure
C)
shaded pole structure
D)
none of these
An induction-cup relay produces comparatively high torque for its size and is efficient in operation.
Legal Metrology • Electrical Engineering Paper-II
Transmission efficiency of a line
A)
decreases with the increase in load p.f
B)
increases with the decrease in load p.f
C)
decreases with the decrease in load p.f
D)
is not related to load p.f
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'increases with the decrease in load p.f' (Option B).
Legal Metrology • Electrical Engineering Paper-II
The direct axis reactance Xd of a synchronous generator is given as 0.4 p.u. based on the generator’s name plate rating of 10kV, 75MVA, the base for calculation is 11kV, 100MVA. What is the p.u. value of Xd on the new base?
A)
0.279
B)
0.44
C)
0.578
D)
0.412
Base conversion: X_new = X_old(S_new/S_old)(V_old/V_new)² = 0.4(100/75)(10/11)² ≈ 0.44 p.u.
Legal Metrology • Electrical Engineering Paper-II
The value of demand factor of a power station is
A)
less than 1
B)
always zero
C)
greater than 1
D)
1.5
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is 'less than 1' (Option A).
Legal Metrology • Electrical Engineering Paper-II
The statutory limit of voltage variation is
A)
+0.6% of declared voltage at customers’ terminals
B)
+10% of declared voltage at customers’ terminals
C)
+6% of declared voltage at customers’ terminals
D)
+1% of declared voltage at customers’ terminals
In the context of Electrical / Electronics Engineering, the most appropriate and technically accurate answer is '+1% of declared voltage at customers’ terminals' (Option D).
Legal Metrology • Electrical Engineering Paper-II
Smaller the damping ratio
A)
keeps the time within limits
B)
larger is the rise time
C)
smaller is the rise time
D)
none of the above
A smaller damping ratio results in a faster initial response, which corresponds to a smaller rise time.
Legal Metrology • Electrical Engineering Paper-II
Lap winding is suitable for
A)
high current, low voltage d.c generators
B)
high current, high voltage d.c generators
C)
low current, low voltage d.c generators
D)
low current, high voltage d.c generators
Lap windings provide many parallel paths, making them suitable for high-current, low-voltage DC machines.
Legal Metrology • Electrical Engineering Paper-II
As compare to Δ-Δ bank, the capacity of the V-V bank of transformers is
A)
57.7%
B)
66.7%
C)
50%
D)
86.6%
A V-V (open-delta) bank has 57.7% of the kVA capacity of an equivalent closed-delta bank.
Legal Metrology • Electrical Engineering Paper-II
The open-loop D.C gain of a unity negative feedback system with overall D.C gain 2/3 is
A)
2
B)
3/2
C)
1/2
D)
2/5
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is '2/5' (Option D).
Legal Metrology • Electrical Engineering Paper-II
The phase crossover frequency of the system G(s) = 10 / [s(s + 20)(s + 10)] is
A)
8.3 rad/sec
B)
14.14 rad/sec
C)
28.2 rad/sec
D)
20 rad/sec
Based on established principles in Electrical / Electronics Engineering, the correct and most clinically/technically appropriate choice is '28.2 rad/sec' (Option C).
Legal Metrology • Electrical Engineering Paper-II
In Merz-Price circulating current scheme of alternator protection, if the value of earth resistance is made to increase, then
A)
the unprotected region against earth fault will also increase
B)
the unprotected region against earth fault will reduce
C)
the unprotected region against earth fault will be only 20%
D)
none of these
Increasing earth-fault resistance makes low-level fault current harder to detect, increasing the unprotected zone.
