IITKGP: Measurements and Electronic Instruments Measurements and Electronic Instruments
Spring 2021
Conducted by Avishek Chatterjee and Prof. Debashis Mandal


SUBJECT NO-EE21004
SUBJECT NAME- MEASUREMENTS AND ELECTRONIC INSTRUMENTS
LTP- 3-1-0,CRD- 4

SYLLABUS:
[Electrical Measurements:] Sensitivity of d.c bridge, measurement of low and high resistances, d.c. potentiometer, principles of a.c. bridges for measurement of L and C; Instrument specifications and error analysis; Extension of Instrument range: CT and PT.D Arsonval Galvanometer, moving coil meters, dynamometer type wattmeter and induction type energymeter, Hall effect sensor
[Electronic Instruments:] Electronic voltmeter, precision rectifiers, true r.m.s voltmeter; basics of digital measurements: A/D and D/A converters, programmable gain amplifier- auto-ranging; comparators and function generators; elements of digital multimeter; clamp-on meter; solid state energymeter, frequency, phase angle and time period measurement. Cathode Ray Oscilloscope, Digital Storage Oscilloscope.Sample and Hold circuits, Data Acquisition Systems.

Syllabus for GATE examination (Section 8)
[Electrical Measurements:] Bridges and Potentiometers, Measurement of voltage, current, power, energy and power factor; Instrument transformers, Error analysis
[Electronic Instruments:] Digital voltmeters and multimeters, Phase, Time and Frequency measurement; Oscilloscopes..

Syllabus for IES examination (Section 4)
[Electrical Measurements:] Units and Standards. Error analysis, measurement of current, Voltage, power, Power-factor and energy. Indicating instruments. Measurement of resistance, inductance, Capacitance and frequency. Bridge measurements.
[Electronic Instruments:] Data acquisition systems. A/D and D/A converters.
[Not covered here:] Transducers and their applications to the measurement of nonelectrical quantities like temperature, pressure, flow-rate displacement, acceleration, noise level etc.




Chapters Reference Videos
1 Electromechanical instruments
Chapter 3 of David Bell's Book
Sections to read:
3-2 (operating forces only),
3-3,
3-4,
3-5 (Only simple attraction and siple repulsion type),
3-6(Excluding Quadrant-type Electrostatic Voltmeter),
3-8		 Handout Problem Set
2 Electromechanical Ammmeters, Voltmeters and Ohmmeters
Chapter 4 of David Bell's Book
Sections to read:
4-1,
4-2,
4-3,
4-4,
4-5
 Handout Problem Set
3 Low, Medium and High Resistance Measurement
Chapter 8 of David Bell's Book
Sections to read:
8-1,
8-2,
8-3 (Only four-terminal Resistors and Kelvin Bridge),
8-5 (only Voltmeter and Ammeter Method and Guard wire and Guard Ring),
8-6 (if time permits only Hand-cranked Megohmmeter)
 Handout Problem Set
4 Electro-mechanical wattmeters and energy meters
Chapter 16 of David Bell's Book
Sections to read:
16-1,
16-2,
16-3 (if time permits),
16-4 (excluding single wattmeter method),
16-5, 16-7 (excluding energy meter error sources and correction) 		Handout Problem Set
5 Potentiometers: DC and AC
Chapter 14 of David Bell's Book
Sections to read:
14-3 (Basic DC Potentiometer),
14-4 (Kelvin-Varley Voltage Divider),
14-5,
Additional: Question: Why or when Potentiometers are used? Ans: No loading current 		Handout Problem Set

Quiz
6 Impedence Measurement: AC Bridges
Chapter 9-10 of David Bell's Book
Sections to read:
9-1,
Chapter 10 Completely,
DON'T Memorize the names of the bridges. We shall never ask you to draw Maxwell, Anderson, Carey-Foster, ... bridges
DO
  • Understand and remember the generic bridge balance equation both in product form as well as ratio form
  • Be able to quickly recognize whether a given bridge can be balanced or not
  • Most bridges are either a product bridge or a ratio bridge, be able to quickly find the balance equation of such a bridge
  • Be able to find bacance equation of any arbitrary bridge
  • Be able to design a product or a ratio bridge to measure an unknown inductance or capacitance and find the balance equation
  • Be able to design a product or a ratio bridge to measure an unknown inductance or capacitance under the constraints such as you do not have any standard inductor (or capacitor) or you do not have standard high (or low) value resistances etc.
  • Understand that in AC bridges the balance is obtained through iterative and alternate tuning where the convergence is an isuue
 Handout Problem Set
7 Instrument transformers: CT & PT
What you should know
  • Why or wnen instrument transformers are used?
  • Equivalent circuit of a transformer
  • Phasor diagram of a transformer
  • Why insturument transformers are used (range changing, safety and other causes)?
  • What is ratio error?
  • What is phase angle error and in what context this is important?
  • To justify from the phasor diagram or equivalent circuit why the leakage impedance should be minimized in a PT?
  • Why the no-load current should be small in a CT?
  • Why the secondary of a PT should never be shorted?
  • why the secondary of a CT should never be opened?
 Handout
9 Miscellaneous
Magnetic Measurement: Chapter 17 of David Bell's Book
Sections to read: 17-2 (Hall effect Sensor), 17-3 (Magnetic Fulx measuremet with a Ballistic Galvanometer)
 Handout
8 Measurement errors
Chapter 2 of David Bell's Book
Sections to read:
2-3,
 Problem Set

Chapter-wise Review Questions


Live Class (for internal students only) WED(12:00-12:55) , THURS(11:00-11:55) , FRI(09:00-10:55)
Youtube Playlist
Boardworks
January 29, 9:00 AM - 10:15 AM
February 24, 12:00 Noon - 1:15 PM
February 25, 11:00 AM - 12:00 Noon
Moodle for class tests