Showing posts with label Electrical & Instrumentation. Show all posts
Showing posts with label Electrical & Instrumentation. Show all posts

What are the functions of capacitors, resistors, diodes, transistors and transducers in electronic or electrical circuits???


What are the functions of capacitors, resistors, diodes, transistors and transducers in electronic or electrical circuits???

A capacitor is an electronic component that stores electrical energy in an electric field. Its primary function is to temporarily store and release electrical energy in a circuit. Capacitors are widely used in various electronic devices and systems for several purposes.

1-Capacitors store electrical energy and release it when needed. They can act as temporary power sources, smoothing out fluctuations in power supply, and providing bursts of energy when required.

2-Capacitors are used to filter out noise and unwanted signals from electrical circuits. They can block DC (Direct Current) while allowing AC (Alternating Current) to pass through, or vice versa.

3-Capacitors, in combination with resistors, can create timing circuits. The rate at which a capacitor charges and discharges can be used to control the timing of various operations in electronic circuits, such as oscillators, timers, and pulse generators.

4-Capacitors can couple two circuits together while allowing DC isolation. This is often used in audio amplifiers and other signal processing circuits to pass AC signals while blocking DC.

5-Capacitors are used in various signal processing applications, such as in audio circuits for coupling, filtering, and impedance matching.

6-In some cases, capacitors are used to provide a phase shift in AC motors during startup, which helps in achieving smooth motor operation.

2-What are the functions of Transistors?

Transistors are semiconductor devices that play a crucial role in modern electronics. They have several functions and are used in a wide range of applications:

1-Transistors amplify electrical signals. They can increase the strength of a weak signal to a higher level, allowing for the transmission of information over long distances or the amplification of audio, radio, or other signals in electronic devices such as amplifiers.

2-Transistors can act as electronic switches, turning electrical currents on or off. They can control the flow of current in a circuit based on the input voltage or current, enabling digital logic operations in computers, microcontrollers, and other digital circuits.

3-Transistors are used in voltage regulator circuits to stabilize and regulate the output voltage. By controlling the amount of current flowing through them, transistors help maintain a constant output voltage despite variations in input voltage or load conditions.

4-Transistors can be used to generate oscillations in electronic circuits, producing periodic signals at specific frequencies.

5-Transistors are used in power control circuits to regulate the amount of power delivered to loads such as motors, heaters, and lights. They can adjust the speed of motors, control the brightness of lights, and regulate the temperature of heating elements.

6-Transistors can be used to generate oscillations in electronic circuits, producing periodic signals at specific frequencies.

3-What are the functions of Transducers?

Transducers are devices that convert one form of energy into another. They play essential roles in various fields, including electronics, measurement, automation, and telecommunications.

1-Transducers can detect and convert physical quantities such as temperature, pressure, force, displacement, acceleration, light intensity, humidity, and many others into electrical signals. These electrical signals can then be processed and analyzed by electronic systems for monitoring, control, or data acquisition purposes.

2-Transducers are widely used in instrumentation and measurement systems to quantify physical parameters accurately. They convert the measured physical quantity into an electrical signal that can be displayed, recorded, or analyzed by measuring instruments or data acquisition systems.

3-Transducers are used in feedback control systems to monitor process variables and adjust control parameters accordingly. For example, in HVAC (Heating, Ventilation, and Air Conditioning) systems, temperature transducers measure room temperature and adjust the heating or cooling systems to maintain a set point temperature.

4-Transducers are used in telecommunications systems to convert electrical signals into electromagnetic waves (transmitters) or vice versa (receivers).

5-Transducers are used in medical imaging devices such as ultrasound machines and MRI (Magnetic Resonance Imaging) scanners to generate images of internal body structures. In ultrasound imaging, for instance, piezoelectric transducers convert electrical signals into mechanical vibrations that produce ultrasound waves used to image tissues.

6-Transducers are employed in renewable energy systems such as solar panels and wind turbines to convert sunlight and wind energy into electrical energy.

7-Transducers are used in security systems, environmental monitoring systems, and industrial process monitoring systems to detect and monitor various conditions and events. For example, motion sensors, gas sensors, and vibration sensors are types of transducers used for detection and monitoring purposes.

 4-What are the functions of resistors?

Resistors are fundamental components in electronics, they perform following functions in electronic/electrical circuit.

1-Resistors are used to create voltage dividers, enabling the division of voltage in a circuit. By placing resistors in series or parallel configurations, different voltages can be obtained across them, which is useful in many applications such as biasing circuits and sensor networks.

2-Resistors limit the amount of current flowing through a circuit. By obeying Ohm's Law (V = IR), where V is voltage, I is current, and R is resistance, resistors restrict the flow of current to a safe level, preventing damage to components and controlling the behavior of circuits.

3-In many electronic devices, resistors act as load resistances, dissipating energy or creating a voltage drop across them. For example, in LED circuits, resistors are used to limit the current flowing through the LED to prevent it from burning out.

4-Resistors are utilized in biasing circuits to establish the operating point of transistors, amplifiers, and other electronic devices.

5-Resistors play a role in signal conditioning by shaping and conditioning electrical signals.

6-Some types of resistors, such as thermistors and RTDs (Resistance Temperature Detectors), exhibit changes in resistance with changes in temperature.

7-In digital circuits and high-frequency applications, resistors are used for termination to minimize signal reflections, impedance mismatches, and noise.

6-What are the functions of signal isolators??

Signal isolators are devices used in electronic circuits to provide electrical isolation between different parts of a system while transmitting signals accurately

1-The primary function of signal isolators is to provide electrical isolation between input and output circuits. This isolation prevents ground loops, eliminates noise interference, and improves system safety by preventing the transmission of potentially hazardous voltages or currents.

2-Signal isolators often include circuitry for signal conditioning, such as amplification, attenuation, filtering, or linearization. This allows the signal to be modified or optimized for the specific requirements of the receiving equipment or system.

3-Signal isolators can convert signals between different voltage or current levels. For example, they may convert a low-voltage sensor signal to a higher voltage suitable for long-distance transmission or for compatibility with the input range of a receiving device.

4-Signal isolators provide galvanic isolation, which means there is no direct electrical connection between input and output circuits. This prevents the flow of current due to ground potential differences, ensuring accurate signal transmission and protecting equipment from damage.

5-Signal isolators enhance system safety by isolating potentially dangerous voltages or currents from sensitive equipment or human operators.

6-In the event of a fault or malfunction in one part of a system, signal isolators prevent the fault from propagating to other parts of the system, minimizing the risk of damage and ensuring system integrity.

7-What are the functions of diodes??

Diodes are semiconductor devices with various functions in electronic circuits

1-One of the primary functions of diodes is rectification, where they convert alternating current (AC) into direct current (DC). This process involves allowing current to flow in one direction while blocking it in the opposite direction, resulting in a pulsating DC output.

2-Diodes are used in voltage regulation circuits to maintain a stable output voltage.

3-Diodes are used in demodulation circuits to extract the original modulating signal from a modulated carrier wave.

4-Diodes are employed in clipping and clamping circuits to modify the shape of wave forms.

5-Diodes serve as protection devices in electronic circuits, safeguarding sensitive components from voltage spikes and reverse voltage conditions.

6-Diodes are used in the construction of logic gates, fundamental building blocks of digital circuits.

7-Diodes are utilized in voltage multiplier circuits

Generator and Turbine intertripping


 On tripping of class A trip of Generator

1-Generator breaker opens

2-Excitation switches off

3-Turbine trips on 86 T relay and followed by closing of ESV and all extractions

4-Turbine speed increases a bit by around 2-3% and gradually speed recedes


 On tripping of class-B trip of Generator

 1-Only generator breaker opens and excitation switches off

2-Turbine rotates on rated speed

3-After normalization of problem, generator synchronized with auxiliary power supply unit and later with grid

4-In case of small turbines, STG clubbed with 86GA to trip Turbine also


 On tripping due to Turbine fault

 1-Relay 86 T gets activated to close turbine ESV all extractions

2-Low forward power or Reverse Power Relay activates first which has time delay, during this time entrapped energy gets consumed by generator

3-Subsequently 86 G relay gets activated to open Generator breaker and followed by excitation gets off

4-Turbine speed does not increase in this case

 Trend of rotor speed on tripping of Turbine and Generator

Read>>>>Powerplant O&M reference books

 On tripping of Generator, instantly generator breaker gets opened and Turbine emergency valve closes.So steam entrapped in Turbine casing causes increase in speed initially and later slows down.

On the other hand,when turbine trips first, generator breaker opens after some time delay through Low forward power or Reverse Power Relay.This time delay helps turbine to consume entrapped steam in casing.As a result turbine generates power and does not allow speed to increase more.

 Relays and significance

Sl No.

Type of relay

Used for



Generator lock out relay



Turbine lock out relay



Generator over voltage @110% alarm and 120% trip



Generator under voltage @90% alarm and 80% trip



Generator Under frequency



Generator over frequency



Generator Reverse Active Power  5 % of Active Power



Generator Reverse Reactive Power



Low forward Power



Negative Phase Sequence 



Generator Over Load



Generator Instantaneous O/C    



Restricted E/F



Rotor E/F2nd Stage

15-Emergencies in power plant operation

Most visited posts