High Voltage Engineering Mid - II, November - 2014

1.Sphere gaps are used to measure ________ voltages.
  • DC
  • AC peak
  • DC,AC peak and impulse
  • DC and AC peaks
Answer: C
2.For measuring high impulse currents, the best type of shunt is
  • squirrel cage
  • bifilar strip
  • disc
  • coaxial tubular (Park type)
Answer: D
3.The electrical field developed within clouds before a lightning stroke occurs can be of the order of ___________ kv/cm
  • 0.1
  • 1
  • 100
  • 10
Answer: D
4.The material used in gap less surge arresters used in HV power system is
  • graphite
  • aluminium oxide
  • zinc oxide
  • silicon carbide
Answer: D
5.The BIL of a power system is usually chosen as _______ more than the protective level offered by the protective devices.
  • 25 – 30%
  • 0.5
  • 5-10%
  • )100%
Answer: A
6.For resistivity and dielectric constant measurements the electrode system used is ______ electrode.
  • two
  • three
  • four
  • six
Answer: B
7.In P.D detectors partial discharges are displayed on
  • any CRO
  • built in CRO with circular time base
  • built in CRO with elliptic time base
  • built in CRO with linear time base
Answer: C
8.Most important tests conducted on isolators and circuit breakers are
  • voltage withstand tests
  • short circuit tests
  • high current tests
  • temperature tests
Answer: B
9.C-tanδ test on electric bushings is done using
  • impulse generator
  • hv Schering bridge
  • resonant transformer
  • power frequency transformer
Answer: B
10.Fault location in an HV cable is done by
  • voltage withstand test
  • partial discharge scanning tests
  • life tests
  • impulse testing
Answer: C
11.In C-tanδ test, a steep increase in tanδ, when the applied voltage increases from 100% to 110% indicates presence of an _________________.
Answer: Internal discharge
12.The salt-fog test done on ______________ is power frequency pollution test.
Answer: Insulators
13.The discharge energy in a partial discharge in terms of discharge magnitude q and inception voltage v is ________________.
Answer: qvi/√2
14.Partial discharge detector is a device that measures a __________________.
Answer: Partial discharge
15.Loss of charge method is used to determine ___________________________.
Answer: Insulation resistance
16.The maximum voltage gradient at the ground level due to a charged cloud before lightning strikes, can be as high as _______________ V/cm
Answer: 300
17.___________________ of a power system is defined as the minimum insulation impulse withstand voltage of any power apparatus.
Answer: Basic impulse level
18.Electrostatic voltmeters can measure _________________________.
Answer: DC and AC voltages up to high frequency
19.Hall generators are normally used to measure _____________________.
Answer: Unidirectional currents
20.Shunts used for measuring impulse currents, in the range 10KA-50KA will have a resistance of order of __________________.
Answer: 10-25mΩ