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- ELectronic Measurement and Instrumentation - EMI
- 2016
- PYQ
**NIT ROURKELA - NITRKL**- Electronics and Communication Engineering
- B.Tech
**3 Views**- Uploaded 1 month ago

Roll No. :- Signature of Student:- Name:- Signature of Invigilator:- NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA-769008 MID-SEMESTER EXAMINATION, 2016 – 2017 (Spring) Subject Name: Electrical and Electronic Measurements Subject Code: EC232 Dept. Code: EC No. of Pages: 2 Full Marks: 30 marks Duration: 2 hrs. Instruction to the candidates: i. ii. iii. iv. Give your name and roll no. and please get the signature of the invigilator above. The question paper consists of 8 questions (30 marks). Answer Q1 to Q4 in the question paper itself and attach to answer sheet. Answer all parts of the question together. Q1. Express the following units in terms of the seven fundamental units of the SI system. (1+1+1= 3 marks) a. Newton : _______________________. b. Watt :_______________________. c. Ohm : ________________________. Q2. The result of any measurement is expressed in terms of ___________________ and ____________________. (1 marks) Q3. Classify the different types of standards based on their function and their application. (2 marks) __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ Q4. Two PMMC ammeters A1 and A2 are available with full scale: 1 mA/100 mV and 1 mA/150 mV respectively. (5 marks) a. Value of shunt required to convert A1 into 10 A full scale ammeter = _______. b. Value of shunt required to convert A2 into 10 A full scale ammeter = _______. c. If by mistake, the shunt of A1 is put on A2 and shunt of A2 is put on A1, the full scale currents of the new ammeters are ____________ and ____________. d. Of the ammeters A1 and A2 which one is better as ammeter and why? _______________________________________________________________ _______________________________________________________________. 1|Page

Q5. A potential divider made of a 100 kΩ resistor in series with a 400 kΩ resistor is powered by a 25 V dc source. (3+3 = 6 marks) a. A 5 V full scale dc voltmeter V1 with figure of merit 20 kΩ/V is used to measure the voltage across the 100 kΩ resistor. What value will the voltmeter read? b. Design an alternate dc voltmeter V2 having a 10 V full scale using the basic PMMC ammeter (used by V1) mentioned in part-a of this question that overcomes the limitations of the V1 used in part-a. Q6. A 100 V full wave rectifier type voltmeter (formed using ideal diodes) reads 60 V. If the waveform of the voltage being read is symmetrical triangular wave, determine the correct rms value of the voltage. What is the percentage error in this reading? (3+1 = 4 marks) Q7. The current through a load is 20 A when the voltage applied to the load is 30 V dc. A wattmeter having resistance of the coils as 0.01 Ω and 1000 Ω respectively was used to measure the power. Assuming both coils as non inductive, (2+3 = 5 marks) a. Show the two ways in which the voltage coil can be connected. b. Find the reading of the wattmeter and the error in the reading in each case. Q8. A sinusoidal ac current having a magnitude Im is sent into a coil of moving iron instrument having a spring constant KS. The coil inductance of the meter changes by dL for a change in the deflection dθ. (3+1 = 4 marks) a. Derive an expression for the deflection angle θ in terms of the above mentioned parameters. Give relevant steps where ever necessary. b. A 5 A full scale moving iron ammeter is built with springs having spring constant KS = 3 nNm/rad. Determine the (dL/dθ) in H/rad of the meter, if the full scale deflection is 600. 2|Page

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