Analog Instruments: Types and Applications

Analog Instruments

• Analog instruments are devices that measure physical quantities, such as pressure, voltage, and current, and display the output in a continuous signal.
• These instruments are extensively used in various applications, including engineering, physics, and chemistry.

Classification of Analog Instruments

• Analog instruments can be classified into three types based on their function:
  • Indicating instruments: These instruments measure the magnitude of a quantity and display the output using a dial and a pointer. Examples include voltmeters, ammeters, and wattmeters.
  • Recording instruments: These instruments record the variations of a quantity over a specific period. Examples include recording voltmeters and oscilloscopes.
  • Integrating instruments: These instruments totalize events over a specific period. Examples include ampere-hour meters and watt-hour meters.

Deflection, Controlling, and Damping Torques

• Deflection torque: The torque required to deflect the pointer of an instrument to a specific position. It is produced by the deflecting system.
• Controlling torque: The torque that opposes the deflection torque and brings the pointer back to its zero position. It is produced by the controlling system.
• Damping torque: The torque that reduces the oscillations of the pointer and helps it to settle quickly. It is produced by the damping system.

Effects Used to Produce Deflecting Torque

• Magnetic effect: Used in most ammeters, voltmeters, and wattmeters. It produces a deflecting torque by using a magnetic field.
• Electromagnetic induction effect: Used in voltmeters, ammeters, and energy meters. It produces a deflecting torque by using electromagnetic induction.
• Heating effect: Used in thermal instruments. It produces a deflecting torque by using the heat generated by the current.
• Chemical effect: Used in integrating instruments. It produces a deflecting torque by using a chemical reaction.
• Electrostatic effect: Used in electrostatic instruments. It produces a deflecting torque by using an electrostatic field.

Torque to Weight Ratio (T/W Ratio)

• The T/W ratio is an important factor in instrument design. It is the ratio of the deflecting torque to the frictional torque.
• A higher T/W ratio indicates a more sensitive instrument.

Analog Voltmeters and Ammeters

• Analog voltmeters measure voltage and display the output using a needle.
• Analog ammeters measure current and display the output using a needle.
• Both types of instruments use a moving coil or a moving iron to measure the quantity.

Comparison with Digital Instruments

• Analog instruments have some advantages over digital instruments, such as:
  • Providing a better idea of the order of magnitude and trends.
  • Not requiring a power supply beyond the test current source.
• However, digital instruments have generally superseded analog instruments due to their superior accuracy and precision.

Scale and Range

• Analog instruments have a scale and range that is determined by the instrument's design.

• The scale and range can be altered by providing a shunt coil or a multiplier.### Merits and Demerits

• Merits refer to favorable circumstances, means, or opportunities that contribute to the success of a desired end.

• Merits also describe the respectable qualities of a thing that make it worthy of respect and praise.

Demerits

• Demerits refer to the marks or characteristics of a thing that are deficient or misconduct.
• Demerits hamper the respect a thing has gained through its merits.

Difference between Merits and Demerits

• Merits are favorable to success, while demerits are unfavorable and have adverse effects.
• Merits refer to advantages or favorable significance, while demerits refer to unfavorable points.

Importance of Considering Merits and Demerits

• When evaluating a thing, it is essential to consider both merits and demerits to make an informed decision.

Examples of Merits and Demerits

Merits of Social Media

• Social media provides a wide social and mental platform for expression.
• It helps small businesses with marketing strategies.
• Social media is beneficial for educational purposes, especially during pandemic times.
• It can aid in job searches and provide opportunities to connect with entrepreneurs.
• Online profiles on LinkedIn help individuals connect with notable entrepreneurs.

Demerits of Social Media

• Oversharing on social media can lead to privacy problems.
• Cyberbullying is a significant disadvantage of social media.
• Social media platforms can spread misinformation.
• Blackmailing and releasing intimate videos on social media can harm reputations.
• Social media lacks the basic essence of mental and emotional connections between people.
• Not everyone is genuine on social media platforms, and it can be misleading.

Electric Drives

• Definition: Electric Drives are electro-mechanical systems designed to control the motion of electrical machines.
• Components: Electric motor, energy transmitting device, and working (or driven) machine.
• Function: Converts electrical energy into mechanical energy to impart motion to machines.

Block Diagram of Electric Drives

• Power Source: Provides power to the system.
• Power Electronic Converter: Converts input electrical energy into a form that can drive the motor.
• Motor: Converts applied energy into mechanical motion.
• Load: Part of the system that requires motion, such as pumps, machines, etc.
• Control Unit and Sensor Unit: Controls the power converter and senses the voltage or current signal as feedback.

Classification of Electric Drives

• DC Drives: Use DC motors and are used in adjustable speed drives and position control.
• AC Drives: Use AC motors and are used in applications such as pumps, machines, etc.

Advantages of Electric Drives

• Flexible motion control
• Easy starting and loading
• High efficiency with low losses and overload capability
• Easy to achieve dynamic load characteristics
• Can perform four-quadrant operation in the Torque/Speed plane

Disadvantages of Electric Drives

• Requires a power supply
• Output power is limited
• Poor dynamic response
• System operation fails in case of power breakouts
• Expensive

Applications of Electric Drives

• Industrial applications: pumps, fans, motors, transportation systems, etc.
• Domestic applications: refrigeration, air conditioning, belt conveyors, etc.

Mechatronics

• Definition: The synergistic combination of mechanical engineering, electronic engineering, control engineering, and systems thinking in the design of products and manufacturing processes.
• Multi-disciplinary approach: combines mechanical, electrical, and software engineering to design and manufacture products.

Evolution of Mechatronics

• Primary Level Mechatronics: Basic control systems with sensors and actuators.
• Secondary Level Mechatronics: Integrates microelectronics into electrically controlled devices.
• Tertiary Level Mechatronics: Incorporates advanced feedback functions and microprocessors.
• Quaternary Level Mechatronics: Includes intelligent control and fault detection capabilities.

Power Transistors

• Definition: Three-terminal devices composed of semiconductor materials, used to control high current-voltage rating.
• Types: Bipolar Junction Transistors (BJTs), Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs), Static Induction Transistors (SITs), and Insulated Gate Bipolar Transistors (IGBTs).

Applications of Power Transistors

• Switch-mode power supplies (SMPS)
• Relays
• Converters
• Power amplifiers
• DC to AC converters
• Power supply
• Power control circuits
• Inverters### Power Transistor Structure
• A bipolar junction transistor (BJT) is a vertically oriented device with a large cross-section area that accommodates alternate P and N-type layers connected together.
• A BJT is composed of PNP or NPN transistors and features three terminals: emitter, base, and collector.

Power Transistor Operation

• Based on forward and reverse bias conditions, a power transistor operates in four regions:
• Cut-off region
• Active region
• Quasi-saturation region
• Hard saturation region

V-I Output Characteristics of a Power Transistor

• The output characteristics show the relationship between VCE and IC.

Advantages and Disadvantages of Power Transistors

• Advantages:
• High voltage gain
• High current density
• Low forward voltage
• Large gain-bandwidth product
• Disadvantages:
• Low thermal stability
• Complex control
• High noise

Applications of Power Transistors

• Power transistors are used in:
• Switch-mode power supplies (SMPS)
• Relays
• Converters
• Power amplifiers
• DC to AC converters
• Power supply
• Power control circuits
• Inverters

SCR (Silicon Controlled Rectifier)

• An SCR is a unidirectional device that allows current to flow in one direction and opposes it in another direction.
• It has three terminals: Anode (A), Cathode (K), and Gate (G).
• SCR Symbol: similar to a diode symbol with an additional gate terminal.

Construction of SCR

• SCR is a four-layered semiconductor device with NPNP or PNPN structure, forming three junctions (J1, J2, and J3).
• The Anode is a P-layer, and the Cathode is an N-layer.
• The Gate acts as a control terminal.
• SCRs are constructed in three types: planar, Mesa, and Press pack.

Working Principle of SCR

• SCR operates in three modes:
• Forward Blocking mode: No current flows due to reverse-biased J2.
• Forward Conduction mode: SCR conducts when voltage exceeds breakdown voltage or a positive voltage is applied to the gate.
• Reverse Blocking mode: No current flows due to reverse-biased J1 and J3.

VI Characteristics of SCR

• Obtained by operating the SCR in three regions: forward blocking, forward conduction, and reverse blocking.
• The graph shows the relationship between voltage and current, including leakage currents and breakdown voltage.

SCR Applications

• SCRs are used in various applications, including:
• Converter circuits
• Control circuits
• Speed control of motors
• Thyristor applications

Electric Drives

• Definition: Electric Drives are electro-mechanical systems designed to control the motion of electrical machines.
• Components: Electric motor, energy transmitting device, and working (or driven) machine.
• Function: Converts electrical energy into mechanical energy to impart motion to machines.

Block Diagram of Electric Drives

• Power Source: Provides power to the system.
• Power Electronic Converter: Converts input electrical energy into a form that can drive the motor.
• Motor: Converts applied energy into mechanical motion.
• Load: Part of the system that requires motion, such as pumps, machines, etc.
• Control Unit and Sensor Unit: Controls the power converter and senses the voltage or current signal as feedback.

Classification of Electric Drives

• DC Drives: Use DC motors and are used in adjustable speed drives and position control.
• AC Drives: Use AC motors and are used in applications such as pumps, machines, etc.

Advantages of Electric Drives

• Flexible motion control
• Easy starting and loading
• High efficiency with low losses and overload capability
• Easy to achieve dynamic load characteristics
• Can perform four-quadrant operation in the Torque/Speed plane

Disadvantages of Electric Drives

• Requires a power supply
• Output power is limited
• Poor dynamic response
• System operation fails in case of power breakouts
• Expensive

Applications of Electric Drives

• Industrial applications: pumps, fans, motors, transportation systems, etc.
• Domestic applications: refrigeration, air conditioning, belt conveyors, etc.

Mechatronics

• Definition: The synergistic combination of mechanical engineering, electronic engineering, control engineering, and systems thinking in the design of products and manufacturing processes.
• Multi-disciplinary approach: combines mechanical, electrical, and software engineering to design and manufacture products.

Evolution of Mechatronics

• Primary Level Mechatronics: Basic control systems with sensors and actuators.
• Secondary Level Mechatronics: Integrates microelectronics into electrically controlled devices.
• Tertiary Level Mechatronics: Incorporates advanced feedback functions and microprocessors.
• Quaternary Level Mechatronics: Includes intelligent control and fault detection capabilities.

Power Transistors

• Definition: Three-terminal devices composed of semiconductor materials, used to control high current-voltage rating.
• Types: Bipolar Junction Transistors (BJTs), Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs), Static Induction Transistors (SITs), and Insulated Gate Bipolar Transistors (IGBTs).

Applications of Power Transistors

• Switch-mode power supplies (SMPS)
• Relays
• Converters
• Power amplifiers
• DC to AC converters
• Power supply
• Power control circuits
• Inverters### Power Transistor Structure
• A bipolar junction transistor (BJT) is a vertically oriented device with a large cross-section area that accommodates alternate P and N-type layers connected together.
• A BJT is composed of PNP or NPN transistors and features three terminals: emitter, base, and collector.

Power Transistor Operation

• Based on forward and reverse bias conditions, a power transistor operates in four regions:
• Cut-off region
• Active region
• Quasi-saturation region
• Hard saturation region

V-I Output Characteristics of a Power Transistor

• The output characteristics show the relationship between VCE and IC.

Advantages and Disadvantages of Power Transistors

• Advantages:
• High voltage gain
• High current density
• Low forward voltage
• Large gain-bandwidth product
• Disadvantages:
• Low thermal stability
• Complex control
• High noise

Applications of Power Transistors

• Power transistors are used in:
• Switch-mode power supplies (SMPS)
• Relays
• Converters
• Power amplifiers
• DC to AC converters
• Power supply
• Power control circuits
• Inverters

SCR (Silicon Controlled Rectifier)

• An SCR is a unidirectional device that allows current to flow in one direction and opposes it in another direction.
• It has three terminals: Anode (A), Cathode (K), and Gate (G).
• SCR Symbol: similar to a diode symbol with an additional gate terminal.

Construction of SCR

• SCR is a four-layered semiconductor device with NPNP or PNPN structure, forming three junctions (J1, J2, and J3).
• The Anode is a P-layer, and the Cathode is an N-layer.
• The Gate acts as a control terminal.
• SCRs are constructed in three types: planar, Mesa, and Press pack.

Working Principle of SCR

• SCR operates in three modes:
• Forward Blocking mode: No current flows due to reverse-biased J2.
• Forward Conduction mode: SCR conducts when voltage exceeds breakdown voltage or a positive voltage is applied to the gate.
• Reverse Blocking mode: No current flows due to reverse-biased J1 and J3.

VI Characteristics of SCR

• Obtained by operating the SCR in three regions: forward blocking, forward conduction, and reverse blocking.
• The graph shows the relationship between voltage and current, including leakage currents and breakdown voltage.

SCR Applications

• SCRs are used in various applications, including:
• Converter circuits
• Control circuits
• Speed control of motors
• Thyristor applications