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Electrical And Electronics Instruments. N Krishna Prakash. UNIT - 2. ELECTRICAL AND ELECTRONICS INSTRUMENTS Principle and types of analog voltmeters Principle and types of digital voltmeters Principle and types of Multimeter Single and three phase wattmeter
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Electrical And Electronics Instruments N Krishna Prakash Nkp/eee skcet
UNIT - 2 ELECTRICAL AND ELECTRONICS INSTRUMENTS Principle and types of analog voltmeters Principle and types of digital voltmeters Principle and types of Multimeter Single and three phase wattmeter Single and three phase energy meters. Magnetic measurements Determination of B-H curve Measurements of iron loss Instrument transformers Instruments for measurement of frequency and phase Nkp/eee skcet 2
Analog Instruments • An analog device is one in which the output or display is a continuous function of time and bears a constant relation to its input. Nkp/eee skcet
Classification • Classified based upon the quantity they measure (ammeter, voltmeter) • Classified according to the current that can be measured by them.(DC,AC) • Classified according to the effects used for working. • Classified as Indicating, Recording, Integrating. • Classified on the basis of method used for comparing the unknown quantity. (Direct / Comparison measurement ) Nkp/eee skcet
Principle of operation • Magnetic Effect. • Thermal Effect. • Electrostatic Effect • Induction Effect. • Hall Effect. Nkp/eee skcet
Magnetic Effect Nkp/eee skcet
Force Between Current carrying Magnet Nkp/eee skcet
Force Between Two Current Carrying Coils Nkp/eee skcet
Hall Effects Nkp/eee skcet
Operating Forces • Deflecting Force. • Controlling Force. • Damping Force. Nkp/eee skcet
Supporting the moving element • Suspension • Taut Suspension • Pivot and jewel bearings. Nkp/eee skcet
Control Systems • Gravity Control. • Spring Control. Nkp/eee skcet
Analog Ammeters • Ammeters are connected in series in the circuit whose current is to be measured. The power loss in an ammeter is I2Ra.Therefore ammeters should have a low electrical resistance so that they cause a small voltage drop and consequently absorb small power. Nkp/eee skcet
Analog Voltmeters • Voltmeters are connected in parallel in the circuit whose voltage is to be measured. The power loss in an ammeter is V2/RV.Therefore voltmeters should have a high electrical resistance so that they cause a small voltage drop and consequently absorb small power. Nkp/eee skcet
Types of Instruments • Permanent magnet moving coil (PMMC). • Moving Iron • Electro-dynamometer type. • Hot wire type. • Thermocouple type. • Induction type. • Electrostatic type. • Rectifier type. Nkp/eee skcet
PMMC Nkp/eee skcet
Moving Iron InstrumentsAttraction Type Nkp/eee skcet
Repulsion Type Moving Iron Instruments Nkp/eee skcet
Electrodynamometer Type Nkp/eee skcet
Wattmeter Nkp/eee skcet
Power Measurement in 3 phase 3 wire system Nkp/eee skcet
Two wattmeter method Nkp/eee skcet
Energy meters Nkp/eee skcet
Single Phase Energy Meter Nkp/eee skcet
Poly Phase Energy Meter Nkp/eee skcet
THANK YOU Nkp/eee skcet