Ø Bold Options are the answers
1. It is desirable to have
wavefront control resistance
(a) entirely within the impulse circuit
(b) entirely outside the impulse circuit
(c)
partly inside and partly outside the impulse circuit
(d) any where
2. The magnitude of pulse
currents depends upon
(a) voltage applied (b) no. of
voids (c) (a) and (b)
3. The frequency spectrum of PD
pulse current contains complete information
concerning
(a) the measurable charge in low
frequency range
( b) apparent
charge in the low frequency range
(c) apparent charge in the high
frequency range
(d) None of the above
4. In order to have proper
integration of the pulse current it is desired
that
(a)
time constant of pulse τ should be greater than
time constant of the measuring circuit (T)
(b)
τ < T (c) τ =
T
(d) time constant has nothing to do with integration of a pulse
current
5. In narrow band PD detection circuit
(a) Parallel combination of RLC
forms measuring impedance
( b)
Parallel combination of RL forms measuring impedance
(c) integration is carried out
on the pulse current
(d) (a) and (c)
6. Recurrent surge generator is
used to generate
(a) current of large magnitude
(b) repetitive current surges
(c)
impulse voltage of smaller magnitude
(d) (b) and (c)
7. For reducing tower footing
resistance it is better to use
(a) chemical and ground rods only (b) chemical and counterpoise only
(c) ground rod and counterpoise only (d) chemical, ground rods and counter poise
8. The impulse ratio of a rod gap is:
(a) unity (b)
between 1.2 and 1.5
(c) between 2.0 and 2.2 (d)
between 1.6 and 1.8
9. The insulation of the modern
EHV lines is designed based on:
(a) The lightning voltage (b)
The switching voltage
(c) Corona
(d) RI
10. High voltage d.c. testing
for HV machines is resorted because
( a)
Certain conclusions regarding the continuous
ageing of an insulation can be drawn
(b) The stress distribution is a
representation of the service condition
(c)
Standardisation on the magnitude of voltage to be applied is available
(d)
The stresses do not damage the coil and insulation
11. Standard impulse testing of
a power transformer requires :
( a) Two
applications of chopped wave followed by one application of a full wave
(b) One application of chopped wave followed
by one applications of a full wave
(c)
One application of chopped wave followed by two applications of a full wave
(d)
None of the above
12. Sphere gap is used for
measurement of
(a) a.c. voltage only (b)
d.c. voltage only
(c) Impulse voltage of any wave shape
(d) (a)
and (b)
13. Sphere gap when used for
measurement of high voltage, the spheres are
placed
( a) in
horizontal configuration if spheres are small
(b) in vertical configuration if
spheres are small
(c)
in horizontal configuration if spheres are large
(d)
(b) and (c)
14. Protective
resistance to be connected between the sphere gap and the test equipment is
required while measuring
( a)
power frequency and higher frequency a.c. voltage
(b) power frequency and impulse
voltage
(c)
Higher frequency a.c. voltages and impulse voltage
(d)
all kinds of voltages
15. If D is the diameter of the sphere, for
better measurements, the gaps ‘S’
should be such that, (a) 0.05 D ≤S
≤0.6 D (b) 0.04 D ≤S ≤0.5
D
(c) 0.05 D ≤S
≤0.5 D (d) 0.03 D ≤S ≤0.6
D
16. Tick out of the correct :
(a) The
breakdown voltage in sphere gaps increases with increase in partial pressure of
water vapour
(b) The increase in breakdown
voltage as in (a) increases with
increase in gap length
(c)
(a)
and (b)
(d) The
breakdown voltage in sphere gaps decreases with increase in partial pressure of
water vapour
17. Using uniform field spark gap, the breakdown voltage for 10 mm gap length is
(a) 34.25 kV
(b) 30.30 kV
(c) 36.25 kV
(d) 32.73 kV
18. The voltage measurements
using uniform spark gap are
(a) affected by nearby earthed objects (b) affected by polarity of supply
(c) affected by dust particles
Very usemopful
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