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This set of Electromagnetic Interference Multiple Choice Questions & Answers (MCQs) focuses on Electromagnetic Interference Set 2
Q1 | Which of the following properties a damping oil must possess ?
- must be a good insulator
- should not have corrosive action upon the metal of the vane
- the viscosity of the oil should not change with the temperature
- all of the above
Q2 | Which of the following devices may be used for extending the range ofinstruments ?
- shunts
- multipliers
- current transformers
- all of the above
Q3 | For handling greater currents induction wattmeters are used inconjunction with
- potential transformers
- current transformers
- power transformers
- either of the above
Q4 | The pointer of an indicating instrument should be
- very light
- very heavy
- either (a) or (b)
- neither (a) nor (b)
Q5 | In majority of instruments damping is provided by
- fluid friction
- spring
- eddy currents
- all of the above
Q6 | An ammeter is a
- secondary instrument
- absolute instrument
- recording instrument
- integrating instrument
Q7 | In a portable instrument, the controlling torque is provided by
- spring
- gravity
- eddy currents
- all of the above
Q8 | The desirable static characteristics of a measuring system are
- accuracy and reproducibility
- accuracy, sensitivity and reproducibility
- drift and dead zone
- static error
Q9 | The ratio of maximum displacement deviation to full scale deviation of theinstrument is called
- static sensitivity
- dynamic deviation
- linearity
- precision or accuracy
Q10 | Systematic errors are
- instrumental errors
- environmental errors
- observational errors
- all of the above
Q11 | The gravity controlled instrument has crowded scale because current isproportional to
- balancing weight
- deflection angle
- sine of deflection angle
- none of the above
Q12 | Instrument transformers are
- potential transformers
- current transformers
- both (a) and (b)
- power transformers
Q13 | The damping force acts on the moving system of an indicating instrumentsonly when it is
- moving
- stationary
- near its full scale deflection
- just staring to move
Q14 | A moving iron ammeter coil has few turns of thickwire in order to have:
- high sensitivity
- effective damping
- low resistance and large current carrying capacity
- large scale
Q15 | Swamping of resistance is used to compensate errordue to:
- stray magnetic field
- temperature variations
- large supply variations
- none of the above
Q16 | The turns ratio for C.T. is defined as
- n2/n1
- n1/n2
- (n1+n2)/n1
- (n1+n2)/n2
Q17 | A 3810/63 P.T. is used with a voltmeter gives reading of 28.11 V , then theactual line voltage is ------ V
- 0.4648
- 975
- 1700
- 1100
Q18 | A 1000:5 C.T. is used with an ammeter. If ammeter reading is 1.8 A then theactual line current is --------------A
- 160
- 400
- 0.09
- 360
Q19 | While testing cables the galvanometer used should be initially short-circuitedin order to protect it from sudden initial inrush currents as the cable have:
- a low value of initial resistance
- a low value of initial capacitance
- a high value of initial capacitance
- both (a) and (b)
Q20 | A megger indicates infinity when test terminals are open-circuited. This isbecause:
- no current flows through the current coil
- no current flows through the pressure coil
- no current flows through the compensating winding
- current does not flow through current coil and pressure coil
Q21 | Potentiometer is an __ instrument:
- indicating
- comparison
- calibrating
- recording
Q22 | Which of the following bridge is frequency sensitive:
- wheatstone bridge
- maxwell bridge
- anderson bridge
- wien bridge
Q23 | The size of the earth or ground wire is based on the:
- maximum fault current carrying through the ground wire
- rated current carrying capacity of the service line
- depends on the soil resistance
- both (a) and (c)
Q24 | Earth wire or ground wire is made of:
- copper
- aluminium
- iron
- galvanized steel
Q25 | Average resistance of human body is:
- 500 ohms
- 1000 ohms
- 1500 ohms
- 2000 ohms