Beu previous year question solution . Electrical and Electronic Measurement 2022 question paper solution. Electrical engineering Bihar engineering university 4th semester question paper and solution.
(a) Power indicated while measuring power in a d.c. circuit using an ammeter and a voltmeter, when the voltmeter is connected to the load side, is
(i) true power consumed by the load (ii) power consumed by the load plus power lost in ammeter
(iii) power consumed by the load plus power lost in voltmeter
(iv) power consumed by load plus power lost in both ammeter and voltmeter
(b) Why should current secondary not be open? transformer
(c) A PMMC instrument has a 0-12 T magnetic flux density in its air gaps. The coil dimensions are D= 1.5 cm and 1= 2:25 cm. Determine the number of coil turns required to give a torque of 4.5 µN-m when the coil current is 100 μА.
(d) The value of series resistance to be used to extent 0 to 200 V range of 20000 /volt voltmeter to 0 to 2000 V is
(1) 36 Ω (ii) 3.6 kn (iii) 3.6 MO (iv) None of the above(Choose the correct answer)
(e) How to prevent creeping in energy meter?
(f) An energy meter is designed to make 100 revolutions of the disc for one unit of energy. Calculate the number of revolutions made by it when connected to a load carrying 40 A at 230 V and 0.4 power factor for an hour.
(g) In a digital oscilloscope, converters are usually the A/D
(i) ramp type
(ii) flash type
(iii) integrating type
(iv) repulsive type (Choose the correct answer)
(h) Why can eddy current damping not be used for moving iron instrument?
(i) Given that, in a Kelvin double bridge circuit, with the usual notations, P=Q=p=q= 1000 ohms, E = 100 V, Rc-5 ohms, R= 500 ohms and the bridge is balanced with S= 0.001 ohm. What is the approximate value of current through S at balance?
(j) The insulation of a metal-sheath electrical cable is tested using 10000 V supply and a microammeter. A current of 5 µA is measured when the compo- nents are connected without guard wire. When the circuit is connect with guard wire, the current is 1.5 μA. Calculate the volume resistance of the cable insulation and the surface leakage resistance.
BEU previous year PDF SOLUTION IS PROVIDED BELOW
2. (a) Show that deflecting torque of an induction-type energy meter is, Td ∞ Pim P2m @ sina cosẞ where notations have their usual meanings.
(b) The meter constant of a 220 V, 5A energy meter is 2000 revolutions per kWh. The meter is tested at half load at, rated voltage and unity power factor. The meter is found to make 34, revolutions in 116 s. Determine the meter error at half load.
(c) A DC voltmeter has a sensitivity of 1000 ohm/watt. When it measures a half full-scale in the 100 V range, calculate the current through the volt- meter.
3. (a) What are the absolute and secondary instruments? Briefly explain different types of secondary instruments
(b) Why is damping required measuring instrument?
(c) Why an ammeter should have a low resistance value?
(d) Why is scale of MI instrument calibrated non-linearly?
4. (a) State the difference between attraction and repulsion-type instrument.
(b) Discuss different types of detectors used in AC bridge.
(c) Draw the circuit diagram of Maxwell’s inductance bridge, and hence calculate the value of unknown inductance. Also, derive the Q-factor.
(d) The impedances of the basic a.c. bridge are given as follows:Z₁ = 100 280° (Inductive) Z₂ = 250 40°Z3=400 230° (Inductive)Z4 = Unknown Calculate the value of impedance.
5. (a) Calculate the power factor of a 3-0 balanced circuit by using two-wattmeter method.
(b) What is phantom loading?
(c) Derive the condition of dissipation factor of a capacitor.
6. (a) Derive expression for actual transfor- mation ratio, ratio error and phasor angle error of a potential transformer.
(b) A 1200/5, C400 CT is connected on the 1000/5 tap. What is the maximum secondary burden that can be used and we can maintain rated accuracy at 20 times rated symmetrical secondary current?
7. (a) What is Lissagous figure? Explain how phase and frequency can be measured through this figure.
(b) A 3-4, 440 V motor load has a p.f. of 0.6. Two wattmeters connected to measure the input. They show the input to be 65 kW. Find the reading of each instrument.
(c) What are the causes of creeping in an energy meter, and how can it be eliminated?
8. (a) State different methods for high resis- tance measurement.(b) Explain the operating principle of PMMC instrument. Derive its torque equation.(c) How to extent the range of PMMC-type ammeter?
9. (a) Draw the basic block diagram of cathode ray oscilloscope.
(b) An electrically deflected CRT has a final anode voltage of 2000 V and parallel deflecting plates 1-5 cm long and 5 mm apart. If the screen is 50 cm from the centre of deflecting plates, find (i) beam speed, (ii) the deflection sensitivity of the tube, and (ii) the deflection factor of the tube.
(c) Explain how the phase angle can be measured by using CRO with proper sketches.
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