To provide the student with an opportunity to acquire knowledge, skills and attitude in the area of Electrical Measurement and Measuring Instruments with special emphasis on :
- extension of instrument range
- operation of instrument transformer.
- measurement of the resistance of various ranges.
- Concept of operation of synchroscope, CRO and High voltage measurement.
- the concept of operation of meters for measurement of frequency, power factor, temperature, pressure, speed and flow.
SHORT DESCRIPTION
Extension of instrument ranges: instrument range; Ammeter shunt, Voltmeter multiplier; Instrument transformer: construction and use of CT & PT; Measurement of resistance: Low resistance, Medium resistance and High resistance; Multimeter; Digital instrument; Frequency Meter: Principle of measurement, construction and operation; Power factor meter: Construction and principles of operation; Digital power factor meter; Synchroscope; Cathode Ray Oscilloscope: construction, operation and application; Electronic voltmeter; Special meters: meters for temperature, pressure, speed and flow measurements.
DETAIL DESCRIPTION
Theory:
EXTENSION OF INSTRUMENT RANGE
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Understand extension of instrument range.
- List different types of instrument for which extension is required.
- Explain the necessity for extension of instrument range.
- Describe the principles of extension of instrument range.
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Understand the concept of ammeter shunt.
- Describe the ammeter shunt for DC circuit.
- Express the deduction of the relation:
- Explain ammeter shunt for AC circuit.
- Solve problems relating to ammeter shunt.
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Understand the concept of voltmeter multiplier.
- Describe voltmeter multiplier.
- Describe the swamping resistance.
- Explain voltmeter multiplier for AC instrument.
- Solve problems relating to voltmeter multiplier.
INSTRUMENT TRANSFORMER
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Understand the concept of instrument transformer.
- Describe current transformer (CT) and potential transformer (PT).
- List the applications of current transformer and potential transformer.
- Explain the advantages and disadvantages of CT and PT.
- Describe the burden of instrument transformer.
- Compare instrument transformer with power transformer.
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Understand the concept of current transformer (CT).
- Describe the construction of current transformer.
- Draw the connection diagram of CT with line.
- Draw and explain the vector diagram of current transformer.
- Determine actual current ratio, ratio error and phase angle error.
- Explain the characteristics of current transformer.
- Explain the classes of accuracy in instrument transformer.
- Explain the effect of open circuited secondary of current transformer.
- Describe the construction and use of clip on ammeters.
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Understand the operation of potential transformer (PT).
- Describe the construction of potential transformer.
- Draw the connection diagram of PT with line.
- Draw the vector diagram of PT.
- Draw the circuit showing CT, PT and Watt meter with 1-phase and 3-phase load.
MEASUREMENT OF RESISTANCE
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Understand the measurement of resistance.
- Classify resistance.
- Explain low, medium and high range of resistance.
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Understand the principle of measurement of low resistance.
- List the methods of measurement of low resistance.
- Describe the measurement of low resistance by ammeter- voltmeter method.
- Describe the measurement of low resistance by Kelvin’s double bridge method.
- Solve problems on Kelvin’s double bridge method.
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Understand the measurement of medium resistance.
- List the method of measurement of medium resistance.
- Describe Wheatstone bridge method of measurement of medium resistance.
- Mention the advantages of Wheatstone bridge method.
- Discuss the precaution in measuring medium resistance by Wheatstone bridge method.
- Solve problems related to Wheatstone bridge method.
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Understand the measurement of high resistance.
- Describe dielectric test of insulating materials.
- List the methods of high resistance measurement.
- Describe the guard wire method of measurement of high resistance.
- Describe the construction and working principle of megger.
- Describe the method of measurement of high resistance by a megger.
- Discuss the uses of megger.
- Describe measurement of earth resistance by earth tester.
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Understand the multimeter.
- Explain the circuit of analog multimeter.
- Describe the construction of analog multimeter.
- Describe the construction of digital multimeter.
- Describe the uses of multimeter.
FREQUENCY METER
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Understand the principle of measurement of frequency.
- Name the methods of measuring frequency.
- Explain the principle of mechanical resonance and electrical resonance.
- Explain variation of impedance of an inductive circuit with the variation of supply frequency.
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Understand the construction and working principle of frequency meter.
- List different types of frequency meter.
- Describe the construction and working principle of electrical resonance frequency meter.
- Describe the construction and working principle of Weston frequency meter.
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Understand the operation of digital frequency meter.
- Describe the principle of operation of digital frequency meter.
- Sketch the block diagram of a digital frequency meter.
- Describe each block of a digital frequency meter.
- Describe the function of time base selector in digital frequency meter.
- Draw and Explain the operation of logic diagram of a digital frequency meter.
POWER FACTOR METER
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Understand the construction and principle of operation of power factor meter.
- List different types of power factor meter.
- Describe construction and principle of operation of single phase dynamometer type power factor meter.
- Describe the construction and principle of operation of three phase dynamometer type power factor meter.
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Understand the principle of operation of digital power factor meter.
- Describe the principle of operation of digital power factor meter.
- Draw the block diagram of a digital power factor meter.
- Describe each block of a digital power factor meter.
SYNCHROSCOPE
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Understand the construction and principle of operation of synchroscope.
- State synchronism and conditions for synchronizing of alternators.
- List the method of synchronization of alternators.
- Describe the construction and working principle of electrodynamometer (Weston) type synchroscope.
- Describe the construction and working principle of moving iron type synchroscope.
CATHODE RAY OSCILLOSCOPE
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Understand the principle of cathode ray oscilloscope.
- List various types electrodes of a cathode ray tube (CRT).
- Sketch the diagram of a cathode ray tube with various electrodes.
- Describe the construction and working principle of a cathode ray tube.
- Draw the block diagram of a basic cathode ray oscilloscope (CRO).
- Describe the function of different control knob in cathode ray oscilloscope.
- Explain the operation of time base generator in CRO.
- Explain the operation of horizontal and vertical amplifier in CRO.
- Describe the function of trigger circuit.
- Describe different wave forms in CRO for different signal inputs.
- Describe the process of measurement of voltage, current, phase and frequency by CRO.
- List the applications of CRO.
- Describe lissajous pattern.
HIGH VOLTAGE MEASUREMENT
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Understand the principle of high voltage measurement and testing.
- Describe the high voltage measurement of electrical quantities.
- List the equipment for high voltage measurement.
- Describe the sphere gap method of high voltage measurement.
- Describe the potential divider method of high voltage measurement.
- Mention the advantages of sphere gap method of high voltage measurement.
- Mention the disadvantages of sphere gap method of high voltage measurement.
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Understand the operation of maximum demand indicator.
- Explain the necessity of maximum demand indicator,
- Describe the construction and working principle of Wright maximum demand indicator and Merz price maximum demand indicator.
- Sketch the connection diagram of maximum demand indicator.
SPECIAL METERS
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Understand the measurement of temperature.
- List the names of temperature measuring meter.
- Describe the principle of operation of electrical resistance thermometer.
- Discuss the requirement of a conductor material to be used in resistance thermometer.
- Describe shortly platinum resistance thermometer.
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Understand the principle of measurement of pressure.
- List different types of pressure measuring meter.
- Describe measurement of pressure by using electrical transducers as secondary transducers.
- Discuss the force summing device.
- Discuss the secondary transducers.
- Describe the measurement of pressure with diaphragm element and inductive transducer.
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Understand the principle of measurement of speed.
- List the names of tachometers.
- Describe a DC tachometer.
- Discuss the disadvantages of a AC tachometer.
- Describe an AC tachometer.
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Understand the principle of measurement of flow.
- Name different flow measuring meter.
- Describe the construction of turbine flow meter.
- Describe the working principle of turbine flow meter.
Practical:
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Determine the shunt resistance of an ammeter for extension of its range.
- Sketch the circuit diagram for determining the shunt resistance of an ammeter.
- Collect the tools, equipment and materials required.
- Prepare the circuit according to the circuit diagram using proper equipment.
- Check the equipment setting and connection before connecting power supply.
- Record the readings from the meter.
- Calculate the value of shunt resistance.
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Determine the value of resistance of a voltmeter multiplier.
- Sketch the circuit diagram for determining the resistance of voltmeter multiplier.
- Connect the tools, equipment and materials required.
- Prepare the circuit according to the circuit diagram.
- Check the circuit before connecting power supply.
- Record the reading from the meter.
- Calculate the value of resistance of the multiplier.
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Perform the handling of instrument transformer.
- Select the current transformer and potential transformer.
- Select required tools, equipment and materials.
- Draw the circuit diagram.
- Connect the equipment according to the circuit diagram.
- Check all connection before supplying energy to the circuit.
- Records reading from the meter and calculate the transformation ratio.
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Perform the measurement of low resistance by Ammeter–Voltmeter method.
- Draw the circuit diagram for the measurement of low resistance by ammeter-voltmeter method.
- Connect the tools, equipment and materials required.
- Prepare the circuit according to the circuit diagram using proper equipment.
- Check the circuit before connecting power supply.
- Record the meter readings.
- Calculate the resistance from the meter readings.
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Perform the measurement of earth resistance by earth tester.
- Sketch the circuit diagram for the measurement of earth resistance by earth tester.
- Select a earth tester and required tools, equipment and materials.
- Connect the equipment according to the circuit diagram.
- Measure the earth resistance from the reading of the earth tester.
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Perform the measurement of medium resistance by wheatstone bridge.
- Draw the circuit diagram for measuring medium resistance by Wheatstone bridge.
- Select tools, equipment and materials required.
- Prepare the circuit according to the circuit diagram.
- Check all the connection before connecting power supply.
- Record the meter readings.
- Calculate the value of unknown resistance.
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Perform the measurement of high resistance by a megger.
- Select a high resistance.
- Select a megger.
- Connect the resistance with the megger.
- Measure the resistance from the reading of the megger.
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Perform the measurement of frequency by a frequency meter.
- Sketch the circuit diagram.
- Select a frequency meter.
- Select tools, equipment and materials.
- Connect the frequency meter to the supply or circuit whose frequency is to be measured.
- Measure the supply frequency from the meter.
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Perform the measurement of power factor by a power factor meter.
- Sketch the circuit diagram for measurement of power factor of a load by a power factor meter.
- Select the tools, equipment and materials required.
- Prepare the circuit according to the circuit diagram by using proper equipment.
- Check the circuit before connecting power supply.
- Record power factor from the power factor meter.
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Perform the measurement by cathode ray oscilloscope and observe wave shape.
- Choose a cathode ray oscilloscope (CRO).
- Select a signal generator.
- Select tools and materials required.
- Connect the signal generator and CRO properly.
- Identify the control and function knobs of signal generator and CRO.
- Energize the signal generator and CRO.
- Observe the operation of different control knobs of CRO.
- Observe wave form on the screen.
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Perform the measurement of voltage, current and frequency by cathode ray oscilloscope (CRO).
- Draw the circuit diagram for the measurement of voltage, current and frequency by CRO.
- Select the tools, equipment and materials required.
- Connect the equipment setting and connection according to the circuit diagram.
- Measure the voltage, current and frequency of the circuit by CRO.
- Prepare a report on it.
12 Measure high voltage peak value.
- Select sphere gap test equipment.
- Connect the sphere gap equipment terminals with high voltage source.
- Adjust the gap up to flash over occurred.
- Take sphere size, gap, length, embient temperature & pressure.
Find the value of voltage by using calibration table and taken data
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