An Introduction to Electrical Instrumentation and Measurement Systems: A guide to the use, selection, and limitations of electrical instruments and measurement systems

1. Introduction
	1.1 Methods of Measurement
		1.1.1 Analogue techniques
		1.1.2 Comparison Techniques
			Substitution Methods
			Null Methods
				The potentiometer
				Bridges
		1.1.3 Digital Techniques
			Sampling of data
			Transmission of data
			Codes
			Memories
			Controllers
			Hardware
			Software
			Firmware
			Programming
			System operation
	1.2 Display Methods
		1.2.1 Analogue Displays
			Pointer Instruments
				Reading interpretation
				Scales
			Graphical Instruments
				Axes
				Permanency of Display
		1.2.2 Digital
			Light emitting diodes
			Liquid-crystal displays
			Gas-discharge display devices
			Cathode ray tube
			Other displays
			Choice of display
	1.3 Accuracy
		1.3.1 Values and Uncertainty
			True value
			Nominal value
			Measured value
			Tolerance and uncertainty
			Example
		1.3.2 Errors
			Error of measurement
			Example
			Sources of error
			Summation of Errors
			Random Errors
		1.3.3 Specifications
			Pointer instruments
			Digital instruments
			Example
		1.3.4 Standards
		1.3.5 Calibration Procedures
	1.4 Input Characteristics
		1.4.1 Sensitivity
		1.4.2 Scaling
			Current division
			Voltage division
		1.4.3 Matching
	1.5 Waveform
		1.5.1 Definitions
			Sinewave
			Mean value
			R.M.S. values
			Form factor and crest factor
			Phase relationships
			Power
			Bias
		1.5.2 Harmonics
		1.5.3 Frequency Effects
			Bandwidth
			Rise time
	1.6 Interference
		1.6.1 Environmental Interference
		1.6.2 Coupled Interference
			Electrostatic coupling
			Electromagnetic coupling
	1.7 Selection
	References

2. Analogue Instruments
	2.1 Moving Coil Instruments
		2.1.1 Null Detectors
			Direct Acting Galvanometers
			Vibration Galvanometer
			Electronic Galvanometer
			Sample Specification
			Tuned A.C. Detectors
			Phase-sensitive Rectifiers (Detectors)
		2.1.2 Multimeters
			Direct Acting Instruments
				Direct current ranges
				Example
				Direct voltage ranges
				Resistance ranges
				Example
				Alternating current ranges
				Alternating voltage ranges
			Sample Specification
			Electronic Instruments
				Direct current ranges
				Direct voltage ranges
				Resistance ranges
				Alternating voltage ranges
			Sample Specification
		2.1.3 Pen Recorders
			Direct Acting Instruments
			Electronic Pen Recorders
			Writing Systems
				Pen
				Fibre pen
				Pressure stylus
				Heated stylus
				Electrical stylus
			Rectilinear Chart Systems
			Sample Specification
		2.1.4 Light Spot Recorders
			Principle of Operation
				Recorder galvanometers
				Damping
				Transient response
				Fluid damped galvanometers
				Electromagnetically damped galvanometer
			Galvanometer Scaling Circuits
				A source of large amplitude
				A source requiring a matched load
				Electronic signal conditioning circuits
			Sample Specification
			Operation
			Galvanometer Selection Factors
				Calibration
				Applications
	2.2 The Electrodynamic Instrument
		2.2.1 Principle
		2.2.2 Application
			Ammeter and Voltmeter
			Wattmeter
	2.3 Other Pointer Instruments
		2.3.1 Moving Iron Instrument
			Properties
		2.3.2 Thermocouple Instruments
			Properties
			Applications
		2.3.3 Electrostatic Instruments
			Properties
		2.3.4 The Q Meter
			Applications
				Determination of inductor properties
				Determination of capacitor properties
	2.4 Energy Meters
	2.5 Solid State Indicators
	2.6 The Cathode Ray Oscilloscope
		2.6.1 Conventional Oscilloscope
			Principle of Operation
				Timebase
				Vertical amplifiers
				X-Y display
				‘Z’ modulator
				Sampling oscilloscopes
				Screen phosphors
				Multiple trace displays
			Oscilloscope Accessories
				Calibrators
				Probes
				Cameras
			Applications
				Voltage measurement
				Current measurement
				Phase angle measurements
				Frequency measurements
				Rise time measurements
			Sample Specification
		2.6.2 Storage Oscilloscopes
			Phosphor storage
			Mesh storage
		2.6.3 Recording Oscilloscopes
	2.7 Instrumentation Tape Recorders
		2.7.1 Direct Recording
		2.7.2 Frequency Modulated Recording
		2.7.3 Pulse Duration Modulation Recording
		2.7.4 Magnetic Recording Heads
		2.7.5 Tape Transport
		2.7.6 Tape Motion Irregularities
			Properties
		References

3. Comparison Methods
	3.1 D.C. Potentiometer
		3.1.1 Commercial Arrangements
			Properties
				Applications
		3.1.2 Pen Recorders
			Process recorders
			Flat bed recorders
			Sample Specification
			X-Y Plotters
		3.1.3 Linear Indicators
	3.2 A.C. Potentiometer
		Example
	3.3 D.C. Bridges
		3.3.1 Wheatstone Bridge
		3.3.2 Low Resistance
		3.3.3 High Resistance
		3.3.4 Unbalanced Bridge
			Principle of operation
			Output characteristics
	3.4 A.C. Bridges
		3.4.1 Classical Bridge
			Detectors
		3.4.2 Single-ratio Transformer Bridges
			Resistance measurement
			Capacitance measurement
			Other uses
		3.4.3 Transformer Double-ratio Bridges
			Applications
				Capacitance measurement
				Measurement of inductance
				Measurement of low impedance
				Measurements of components ‘in situ’
				Network characteristics
			Sample Specification
		3.4.4 Twin ‘T’ Networks
			Principle of operation
	3.5 Self-balancing Bridges
		Principle of operation
	References

4. Digital Instruments
	4.1 Counters
		4.1.1 Principle of Operation
			Asynchronous counters
			Synchronous counters
			BCD to decimal converters
			Operational Modules
				Count and display
				Internal oscillator
				Decade dividers
				Main gate
				Input circuitry
				Selector switches and control logic
		4.1.2 Totalise or Count
		4.1.3 Frequency Measurement
		4.1.4 Period and Multiple-period Measurement
			Sample Specification
		4.1.5 Frequency Ratio Measurements
			Sample Specification
		4.1.6 Time Interval Measurements
	4.2 Multi-function Digital Voltmeters
		4.2.1 Analogue to Digital Conversion
			Successive approximation method
			Ramp method
			Voltage to frequency method
			Dual slope technique
		4.2.2 Voltage Measurement
			Direct Voltage
			Sample Specification
			Alternating Voltage
			Sample Specification
		4.2.3 Current Measurement
			Sample Specification
		4.2.4 Resistance Ranges
			Sample Specification
	4.3 ‘Intelligent’ Instruments
		4.3.1 Concepts
		4.3.2 Voltage Facilities
			Automatic Calibration
			Functional Programs
				Uncertainty read out
				Percentage deviation
				Multiplication
				Offset
				Ratios
				Maximum and minimum
				Limits
				Statistics
				Linearisation
				Time
				Combination of programmes
		4.3.3 Resistance Measurement
	4.4 Hybrid Instruments
		4.4.1 Component Measurements
			Sample Specification
		4.4.2 Power Measurement
		4.4.3 Recorders
			Programmable recorders
		4.4.4 Spectrum Analysers
		4.4.5 Logic Analysers
			Timing Analysers
			State Analysers
		4.4.6 Data Analysers
			Pulse Height Analysers
			Correlator
				Autocorrelation function
				Cross-correlation function
		References

5. Transducers
	Definitions
		Transducers
		Fixed reference devices
		Mass-spring or seismic device
		Transducer classification
	5.1 Resistance Change Transducers
		5.1.1 Potentiometric Transducers
			Example
		5.1.2 Resistance Strain Gauges
			Gauge factor
			Vibratory movement
			Temperature effects
		5.1.3 Measuring Circuits
			Example
			Bridge Balancing
				Lead resistance
			Strain Gauge Attachment
			Applications
		5.1.4 Resistance Strain Gauge Transducers
		5.1.5 Other Resistance Change Transducers
			Resistance Thermometer
			Hot Wire Anemometers
			Humidity Gauges
	5.2 Reactance Change Transducers
		5.2.1 Capacitance Variation
			Variable dielectric
			Variable plate area
			Variable plate separation
			Measuring techniques
		5.2.2 Inductance Variation
		5.2.3 Linear Variable Differential Transformer (L.V.D.T.)
			‘Synchro’
	5.3 Semiconductor Devices
		5.3.1 Thermistors
		5.3.2 Semiconductor Strain Gauges
		5.3.3 Photodiodes and Phototransistors
	5.4 Self-generating Transducers
		5.4.1 Electromagnetic Transducers
			Linear velocity transducer
			Angular devices
			Toothed rotor tachometer
		5.4.2 Piezoelectric Transducers
		5.4.3 Thermoelectric Transducers
			Thermocouple
			Output measurement
			Thermocouple materials
	5.5 Ultrasonic Transducers
	5.6 Digital Transducers
		Digital encoder
	References

6. Signal Conditioning
	6.1 Voltage Scaling
		6.1.1 Resistance Divider
			Resistance chain
			Kelvin-Varley divider
		6.1.2 Capacitive Divider
		6.1.3 Resistance-Capacitance Divider
		6.1.4 Inductive Divider
			Principle of operation
		6.1.5 Voltage Transformer
			Example
	6.2 Current Scaling
		6.2.1 Current Shunts
			Four-terminal Shunts
			Universal Shunt
				Example
		6.2.2 Current Transformers
			Alternating Current Transformers
			Direct Current Transformers
	6.3 Attenuators
		6.3.1 Resistance Attenuators
			Basic Attenuator Pad
			Symmetrical T Attenuators
			π Attenuators
			Balanced Attenuators
		6.3.2 Instrument ‘Input Attenuators’
	6.4 Filters
		Categories
		6.4.1 Passive Filters
			High Pass Filters
			Low Pass Filters
			Band Pass Filters
		6.4.2 Active Filters
			Band Pass Filter
		6.4.3 Digital Filters
	6.5 Probes
		6.5.1 Passive Probes
			Input Impedance Effects
			Signal Response
				Response to step function
				Response to sinewave
		6.5.2 Active Voltage Probes
		6.5.3 Current Probes
	6.6 Modulation and Sampling
		Modulators
		Sampling
	6.7 Analogue Processing
		6.7.1 Amplification
			Attenuated feedback
			Charge amplifier
			Differential amplifier
		6.7.2 Mathematical Functions
			Using Operational Amplifiers
				Summing amplifier
				Computing amplifier
				Logarithmic converter
				Mean or average values
			Using Multipliers
				Multiplication
				Division
				R.M.S. values
		6.7.3 Dependent Functions
			Voltage to frequency converter
			Linearisers
			Voltage to current amplifier
	6.8 Digital-Analogue Conversion
	References

7. Interference and Screening
	7.1 Environmental Effects
		7.1.1 Thermal Effects
			Expansion coefficient
			Resistance coefficient
			Thermoelectric generation
		7.1.2 Humidity Effects
			Leakage resistance
			Galvanic voltages
		7.1.3 Pressure
		7.1.4 Multiple Earths and Earth Loops
		7.1.5 Inherent Noise
	7.2 Component Impurities
		7.2.1 Frequency Effects
		7.2.2 Resistor Impurities
		7.2.3 Inductor Properties
		7.2.4 Capacitor Properties
		7.2.5 Component Impurity Effects on Signals
	7.3 Coupled Interference
		7.3.1 Electrostatic Interference
			Instrument screen connections
			Transformer screening
			Amplifier screening
			Faraday cage
			Guard rings
		7.3.2 Electromagnetic Interference
		7.3.3 Cross Talk
	7.4 Noise Rejection Specifications
		7.4.1 Normal Mode Noise
		7.4.2 Common Mode Noise
			Floating instruments
			Example
			Example
			Guarded voltmeter
		7.4.3 Signal-to-noise Ratio
		References

8. Instrument Selection and Specification Analysis
	8.1 Instrument Selection
		Ranges
		Accuracy
		Response Characteristics
		Input Characteristics
		Output Characteristics
		Stability
		Environment
		Isolation and Screening
		Operation
		Reliability
	8.2 Specification Analysis
		Example
		General data
		Direct voltage measurement
		Resistance measurement
		Current measurement
		Alternating voltage measurement
		Best buy decision
	References

9. Instrumentation Systems
	Definition
	9.1 System Design
		Type of System
	9.2 Analogue Systems
		9.2.1 Open Loop Systems
			Problem 1
				An outline solution
			Problem 2
				An outline solution
		9.2.2 Closed Loop Systems
	9.3 Digital Systems
		9.3.1 Data Loggers
		9.3.2 Bus-connected Systems
			System structure or architecture
			The IEC Bus
				The data bus
				The ‘handshake’ function
				General interface management
				Addressing an instrument
				Operating arrangements
			Applications
				Data logging
				Calibration system
	References

10. Problems and Exercises
	10.1 Principles
	10.2 Analogue Instruments
	10.3 Null or Comparison Measurements
	10.4 Digital Instruments
	10.5 Transducers
	10.6 Signal Conditioning
	10.7 Interference
	10.8 Selection
	10.9 Systems
	10.10 Answers

Appendix I: Units, Symbols and Conversion Factors
Appendix II: Dynamic Behaviour of Moving Coil Systems
	a. Equation of motion; damping magnitude
	b. Deflection amplitude of vibration galvanometer
	c. Amplitude and phase distortion of a u.v. recorder galvanometer
Appendix III: Equations to Determine the components of a Resistive ‘T’ Attenuator Pad
Index