Electrical and Electronic Measurements
ELECTRICAL AND ELECTRONIC MEASUREMENTS
Measurement of Resistance: Wheatstone’s bridge, sensitivity, limitations. Kelvin’s double bridge. Earth resistance measurement by fall of potential method and by using Megger.
Measurement of Inductance and Capacitance: Sources and detectors, Maxwell’s inductance and capacitance bridge, Hay’s bridge, Anderson’s bridge, Desauty’s bridge, Schering bridge. Shielding of bridges. Problems.
Measurement of Power, Energy, Power Factor and Frequency: Torque expression, Errors and minimization, UPF and LPF wattmeters. Measurement of real and reactive power in 3 phase circuits. Errors, adjustments and calibration of single and three phase energy meters, Problems. Construction and operation of single-phase and three phase dynamometer type power factor meter. Weston frequency meter and phase sequence indicator.
Extension of Instrument Ranges: Desirable features of ammeters and voltmeters. Shunts and multipliers. Construction and theory of instrument transformers, Desirable characterises, Errors of CT and PT. Turns compensation, Illustrative examples, Silsbee’s method of testing CT. Magnetic measurements: Introduction, measurement of flux/ flux density, magnetising force and leakage factor.
Electronic and Digital Instruments: Introduction. Essentials of electronic instruments, Advantages of electronic instruments. True rms reading voltmeter. Electronic multimeters. Digital voltmeters (DVM) – Ramp type DVM, Integrating type DVM and Successive – approximation DVM. Q meter. Principle of working of electronic energy meter (with block diagram), extra features offered by present-day meters and their significance in billing
Display Devices: Introduction, character formats, segment displays, Dot-matrix displays, Bar graph displays. Cathode ray tubes, Light emitting diodes, Liquid crystal displays, Nixes, Incandescent, Fluorescent, Liquid vapour and Visual displays.
Recording Devices: Introduction, Strip chart recorders, Galvanometer recorders, Null balance recorders, Potentiometer type recorders, Bridge type recorders, LVDT type recorders, Circular chart and recorders. Digital tape recording, Ultraviolet recorders. Electro Cardio Graph (ECG)