Tap changers are devices fitted to power transformers that allow for regulation of the output voltage. Voltage regulation is achieved by altering the number of turns in one winding of the transformer, which changes the transformer ratios. Tap changers offer variable control to keep the supply voltage within limits. They can be on load or off load tap changers. On load tap changers consist of a diverter switch and selector switch to transfer current between taps without interruption.
Tap changers are devices fitted to power transformers that regulate output voltage levels by altering the transformer turn ratios (paragraph 1). On-load tap-changers (OLTCs) are commonly used in power grids and industries to continuously regulate voltage during operation (paragraph 2). OLTCs offer variable control to maintain supply voltage within specified limits by selecting different transformer taps, which correspond to different turn ratios and voltage outputs (paragraphs 3-5). Modern OLTCs are designed to change taps while energized since off-load tap changers interrupt power supply (paragraph 6).
The document discusses protection schemes for transformers. It describes faults that can occur in transformers such as open circuits, overheating, and winding short circuits. It then discusses different protection systems for transformers including Buchholz relays, earth fault relays, overcurrent relays, and differential protection systems. Differential protection systems operate by comparing currents from current transformers on both sides of the transformer and tripping the circuit breaker if a difference is detected, indicating an internal fault. The combination of protection schemes provides comprehensive protection for transformers.
Operation and maintenance of transformerKapil Singh
The document provides information on operation and maintenance of distribution transformers. It defines transformers and describes their working principle of mutual electromagnetic induction. It then discusses transformation ratios, the purposes of transformers, their advantages, types, parts, insulation, testing, and maintenance procedures. Key points covered include daily, quarterly and yearly maintenance checks, oil testing parameters, and common transformer tests like ratio, no load, short circuit and insulation tests.
Distribution transformers are used to reduce high primary voltages to lower utilization voltages for consumers. They come in various types including large distribution transformers used to receive energy from high voltage levels and distribute to substations or industries, and single-phase pole mounted transformers used for residential overhead distribution. Voltage regulation is the percentage difference between no-load and full-load voltages, and is affected by the voltage drop due to current flowing through the transformer windings. Losses in distribution transformers include core losses, copper losses from winding resistance, and stray losses from stray fluxes.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
The document lists the main parts of a transformer as: metallic core, holding frame, winding, on load tap changer, bushings and terminals, radiator wings/cooling tubs, breather, Buchholz relay, explosion valve, control panel, and tank. It provides the names of the core components that make up a transformer.
We are providing info about power transformer parts and their functions. Power transformer is very useful in transmission network of higher voltage for step-up and step down.
Tap changers are devices fitted to power transformers that regulate output voltage levels by altering the transformer turn ratios (paragraph 1). On-load tap-changers (OLTCs) are commonly used in power grids and industries to continuously regulate voltage during operation (paragraph 2). OLTCs offer variable control to maintain supply voltage within specified limits by selecting different transformer taps, which correspond to different turn ratios and voltage outputs (paragraphs 3-5). Modern OLTCs are designed to change taps while energized since off-load tap changers interrupt power supply (paragraph 6).
The document discusses protection schemes for transformers. It describes faults that can occur in transformers such as open circuits, overheating, and winding short circuits. It then discusses different protection systems for transformers including Buchholz relays, earth fault relays, overcurrent relays, and differential protection systems. Differential protection systems operate by comparing currents from current transformers on both sides of the transformer and tripping the circuit breaker if a difference is detected, indicating an internal fault. The combination of protection schemes provides comprehensive protection for transformers.
Operation and maintenance of transformerKapil Singh
The document provides information on operation and maintenance of distribution transformers. It defines transformers and describes their working principle of mutual electromagnetic induction. It then discusses transformation ratios, the purposes of transformers, their advantages, types, parts, insulation, testing, and maintenance procedures. Key points covered include daily, quarterly and yearly maintenance checks, oil testing parameters, and common transformer tests like ratio, no load, short circuit and insulation tests.
Distribution transformers are used to reduce high primary voltages to lower utilization voltages for consumers. They come in various types including large distribution transformers used to receive energy from high voltage levels and distribute to substations or industries, and single-phase pole mounted transformers used for residential overhead distribution. Voltage regulation is the percentage difference between no-load and full-load voltages, and is affected by the voltage drop due to current flowing through the transformer windings. Losses in distribution transformers include core losses, copper losses from winding resistance, and stray losses from stray fluxes.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
The document lists the main parts of a transformer as: metallic core, holding frame, winding, on load tap changer, bushings and terminals, radiator wings/cooling tubs, breather, Buchholz relay, explosion valve, control panel, and tank. It provides the names of the core components that make up a transformer.
We are providing info about power transformer parts and their functions. Power transformer is very useful in transmission network of higher voltage for step-up and step down.
This document describes various protection schemes for transformers, including differential, restricted earth fault, overcurrent, and thermal protection.
1) Differential protection compares currents entering and leaving the transformer zone to detect internal faults. It provides the best protection for internal faults.
2) Restricted earth fault protection is used to detect high-resistance winding-to-core faults not detectable by differential relays. It uses a neutral current transformer and is sensitive to internal earth faults.
3) Overcurrent protection uses relays with current coils to detect overloads and faults above a pickup threshold. It also includes ground-fault protection.
This document discusses power system protection settings and provides information on calculating protection settings. It covers the functions of protective relays and equipment protection, the required information for setting calculations such as line parameters and fault studies, and the process of calculating, checking, and implementing protection settings. The goal is to set protections to operate dependably, securely, and selectively during faults while meeting clearance time requirements.
Static relays use electronic components like semiconductors instead of mechanical parts to detect faults and operate. They have components like rectifiers to convert AC to DC, level detectors to compare values to thresholds, and amplifiers and output devices to trigger trips. The document discusses the components, types, and applications of various static relays like overcurrent, directional, differential, distance and instantaneous relays used in power system protection.
This document discusses the testing and maintenance of power transformers. It outlines the various routine tests performed on transformers according to standards, including winding resistance measurement, insulation resistance measurement, high voltage tests, no load and load loss measurements. It also describes type tests such as lightning impulse and short circuit tests. Finally, it discusses the importance of preventive maintenance through regular checks of oil levels, insulation resistance, bushings, connections and other components.
This presentation discusses the key protection devices used in electrical substations. It introduces current transformers and potential transformers, which reduce current and voltage levels for protection relays. Relays detect faults by measuring currents and voltages. When a fault is detected, relays signal circuit breakers to isolate the faulty component. Other protection devices discussed include lightning arresters, isolators, and surge diverters. The objective of the substation protection system is to isolate only faulty parts of the network while keeping the rest operational.
1. Overcurrent relays can be classified based on technology and function, and include definite time, inverse time, and IDMT relays.
2. Time-current characteristics of overcurrent relays can be adjusted through settings like current, time multiplier, and plug settings to achieve selective coordination between relays.
3. Common overcurrent protection schemes include time-graded systems using definite time relays, current-graded systems using instantaneous relays, and combinations of both for selective coordination on radial distribution feeders.
On Load Tap Changer (OLTC) is used in "High Power Transformers" to control output voltage, when electric load on transformers get increase the output voltage get decrease due to internal voltage drop inside winding, change in tap is required to maintain output voltage. OLTC is a device which perform tap changing in High Power Transformers during On Load conditions and is powered by a motor.
This document provides a summary of key aspects of transformer basics:
- It describes the working principle of transformers using Faraday's law of electromagnetic induction and discusses the main parts of a transformer including its magnetic core and windings.
- It lists different types of transformers classified by their use, construction, cooling method and other factors. Common types include distribution, power, control, and instrument transformers.
- Key aspects of distribution transformers like primary and secondary voltages, capacities, construction types and impedance ranges are outlined.
- Star and delta connections are explained along with diagrams and equations relating line and phase voltages. Advantages and disadvantages are also summarized.
- Other transformer components like tap changers, bushings
This document summarizes various protection schemes for power transformers, including:
1. Differential protection compares currents entering and leaving the transformer to detect internal faults.
2. Buchholz relay detects incipient faults by sensing gases produced from insulation breakdown, and can indicate the fault type.
3. Restricted earth fault protection detects high-resistance winding-to-core faults not seen by differential relays.
4. Overcurrent protection trips for overloads or external faults not isolated by other schemes.
5. Overfluxing protection monitors the voltage-to-frequency ratio to prevent damage from sustained overvoltages.
HIGH VOL TAGE TESTING OF TRANSFORMER BY HARI SHANKAR SINGHShankar Singh
1. The document discusses high voltage testing of electrical transformers, including various types of tests like partial discharge testing, impulse testing, turns ratio testing, and insulation resistance testing.
2. These tests help check the insulation quality, detect defects, verify voltage ratios, and ensure transformers can withstand high voltage surges to prevent failures.
3. High voltage testing provides advantages like improved safety, energy efficiency, lower costs, and failure detection; but can also have disadvantages like not removing the root causes of failures.
This document provides an overview of the EE2402 Protection & Switchgear course presented by C.Gokul. It includes the course syllabus, units covered, textbook references and introductory content on power system basics, components, faults, protection elements, relay terminology and essential qualities of protection systems. The key topics discussed are types of faults in power systems, importance of protective schemes, elements of a protection system including current transformers, voltage transformers, relays and circuit breakers. Neutral earthing methods with a focus on Peterson coil are also introduced.
This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.
The major components of a typical substation include air circuit breakers, buses, capacitors, circuit switchers, conduits, control houses, converter stations, current transformers, disconnect switches, distribution buses, duct runs, frequency changers, grounding equipment, high-voltage cables, fuses, lightning arresters, manholes, metal-clad switchgear, meters, microwave systems, oil circuit breakers, potheads, and voltage transformers. Capacitor voltage transformers are used to transform high voltages to low voltages suitable for meters, relays and other equipment and provide insulation between high voltage and low voltage circuits.
EHV (extra high voltage) AC transmission refers to equipment designed for voltages greater than 345 kV. Higher transmission voltages increase efficiency by reducing transmission losses and current, decrease infrastructure costs, and increase transmission capacity. However, they also present safety and interference risks. New technologies like FACTS (flexible AC transmission systems) help maximize the benefits of EHV transmission by enabling voltage control and power flow management. There is growing support for expanding national EHV transmission grids to facilitate large-scale renewable energy integration and inter-regional power sharing.
A chopper is a static device that uses pulse width modulation or variable frequency control to obtain a variable DC output voltage from a constant DC input voltage. Choppers are widely used to control motors and regenerate braking energy. The document describes different types of choppers - Type A chops the input voltage to produce positive output voltage and current. Type B allows regenerative braking by producing negative current. Type C operates in both quadrants while Type D's output voltage can be positive or negative.
This document discusses different types of directional over current relays. It explains that directional over current relays operate when fault current flows in a particular direction and will not operate if power flows in the opposite direction. It provides details on 30 and 90 degree connections for directional relays and describes the construction and operation of non-directional over current relays and shaded pole type directional over current relays.
A protective relay is a device that detects abnormal conditions in an electrical circuit, such as a fault, and triggers a circuit breaker to disconnect the faulty part of the circuit. There are several types of relays including definite time, differential, solid state, electromechanical, backup, current, voltage, and frequency relays. A differential relay compares currents on both sides of a power transformer to detect faults. Solid state relays have no moving parts, allowing for high-speed operation. Electromechanical relays use a spring, armature, electromagnet and contacts to close the circuit when energized. Protection schemes use primary and backup relays, with primary relays clearing faults fastest and backup relays removing more of
This document discusses power electronics and drives, including AC converters and electrical drives. It covers inverters that convert DC to AC, including half-bridge and full-bridge single-phase inverters. It also discusses AC-AC converters like AC voltage controllers and cycloconverters. For electrical drives, it defines them, compares mechanical and electrical drives, and shows the basic block diagram of an electrical drive system including the power source, power modulator, motor, load, and control unit.
This document describes various protection schemes for transformers, including differential, restricted earth fault, overcurrent, and thermal protection.
1) Differential protection compares currents entering and leaving the transformer zone to detect internal faults. It provides the best protection for internal faults.
2) Restricted earth fault protection is used to detect high-resistance winding-to-core faults not detectable by differential relays. It uses a neutral current transformer and is sensitive to internal earth faults.
3) Overcurrent protection uses relays with current coils to detect overloads and faults above a pickup threshold. It also includes ground-fault protection.
This document discusses power system protection settings and provides information on calculating protection settings. It covers the functions of protective relays and equipment protection, the required information for setting calculations such as line parameters and fault studies, and the process of calculating, checking, and implementing protection settings. The goal is to set protections to operate dependably, securely, and selectively during faults while meeting clearance time requirements.
Static relays use electronic components like semiconductors instead of mechanical parts to detect faults and operate. They have components like rectifiers to convert AC to DC, level detectors to compare values to thresholds, and amplifiers and output devices to trigger trips. The document discusses the components, types, and applications of various static relays like overcurrent, directional, differential, distance and instantaneous relays used in power system protection.
This document discusses the testing and maintenance of power transformers. It outlines the various routine tests performed on transformers according to standards, including winding resistance measurement, insulation resistance measurement, high voltage tests, no load and load loss measurements. It also describes type tests such as lightning impulse and short circuit tests. Finally, it discusses the importance of preventive maintenance through regular checks of oil levels, insulation resistance, bushings, connections and other components.
This presentation discusses the key protection devices used in electrical substations. It introduces current transformers and potential transformers, which reduce current and voltage levels for protection relays. Relays detect faults by measuring currents and voltages. When a fault is detected, relays signal circuit breakers to isolate the faulty component. Other protection devices discussed include lightning arresters, isolators, and surge diverters. The objective of the substation protection system is to isolate only faulty parts of the network while keeping the rest operational.
1. Overcurrent relays can be classified based on technology and function, and include definite time, inverse time, and IDMT relays.
2. Time-current characteristics of overcurrent relays can be adjusted through settings like current, time multiplier, and plug settings to achieve selective coordination between relays.
3. Common overcurrent protection schemes include time-graded systems using definite time relays, current-graded systems using instantaneous relays, and combinations of both for selective coordination on radial distribution feeders.
On Load Tap Changer (OLTC) is used in "High Power Transformers" to control output voltage, when electric load on transformers get increase the output voltage get decrease due to internal voltage drop inside winding, change in tap is required to maintain output voltage. OLTC is a device which perform tap changing in High Power Transformers during On Load conditions and is powered by a motor.
This document provides a summary of key aspects of transformer basics:
- It describes the working principle of transformers using Faraday's law of electromagnetic induction and discusses the main parts of a transformer including its magnetic core and windings.
- It lists different types of transformers classified by their use, construction, cooling method and other factors. Common types include distribution, power, control, and instrument transformers.
- Key aspects of distribution transformers like primary and secondary voltages, capacities, construction types and impedance ranges are outlined.
- Star and delta connections are explained along with diagrams and equations relating line and phase voltages. Advantages and disadvantages are also summarized.
- Other transformer components like tap changers, bushings
This document summarizes various protection schemes for power transformers, including:
1. Differential protection compares currents entering and leaving the transformer to detect internal faults.
2. Buchholz relay detects incipient faults by sensing gases produced from insulation breakdown, and can indicate the fault type.
3. Restricted earth fault protection detects high-resistance winding-to-core faults not seen by differential relays.
4. Overcurrent protection trips for overloads or external faults not isolated by other schemes.
5. Overfluxing protection monitors the voltage-to-frequency ratio to prevent damage from sustained overvoltages.
HIGH VOL TAGE TESTING OF TRANSFORMER BY HARI SHANKAR SINGHShankar Singh
1. The document discusses high voltage testing of electrical transformers, including various types of tests like partial discharge testing, impulse testing, turns ratio testing, and insulation resistance testing.
2. These tests help check the insulation quality, detect defects, verify voltage ratios, and ensure transformers can withstand high voltage surges to prevent failures.
3. High voltage testing provides advantages like improved safety, energy efficiency, lower costs, and failure detection; but can also have disadvantages like not removing the root causes of failures.
This document provides an overview of the EE2402 Protection & Switchgear course presented by C.Gokul. It includes the course syllabus, units covered, textbook references and introductory content on power system basics, components, faults, protection elements, relay terminology and essential qualities of protection systems. The key topics discussed are types of faults in power systems, importance of protective schemes, elements of a protection system including current transformers, voltage transformers, relays and circuit breakers. Neutral earthing methods with a focus on Peterson coil are also introduced.
This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.
The major components of a typical substation include air circuit breakers, buses, capacitors, circuit switchers, conduits, control houses, converter stations, current transformers, disconnect switches, distribution buses, duct runs, frequency changers, grounding equipment, high-voltage cables, fuses, lightning arresters, manholes, metal-clad switchgear, meters, microwave systems, oil circuit breakers, potheads, and voltage transformers. Capacitor voltage transformers are used to transform high voltages to low voltages suitable for meters, relays and other equipment and provide insulation between high voltage and low voltage circuits.
EHV (extra high voltage) AC transmission refers to equipment designed for voltages greater than 345 kV. Higher transmission voltages increase efficiency by reducing transmission losses and current, decrease infrastructure costs, and increase transmission capacity. However, they also present safety and interference risks. New technologies like FACTS (flexible AC transmission systems) help maximize the benefits of EHV transmission by enabling voltage control and power flow management. There is growing support for expanding national EHV transmission grids to facilitate large-scale renewable energy integration and inter-regional power sharing.
A chopper is a static device that uses pulse width modulation or variable frequency control to obtain a variable DC output voltage from a constant DC input voltage. Choppers are widely used to control motors and regenerate braking energy. The document describes different types of choppers - Type A chops the input voltage to produce positive output voltage and current. Type B allows regenerative braking by producing negative current. Type C operates in both quadrants while Type D's output voltage can be positive or negative.
This document discusses different types of directional over current relays. It explains that directional over current relays operate when fault current flows in a particular direction and will not operate if power flows in the opposite direction. It provides details on 30 and 90 degree connections for directional relays and describes the construction and operation of non-directional over current relays and shaded pole type directional over current relays.
A protective relay is a device that detects abnormal conditions in an electrical circuit, such as a fault, and triggers a circuit breaker to disconnect the faulty part of the circuit. There are several types of relays including definite time, differential, solid state, electromechanical, backup, current, voltage, and frequency relays. A differential relay compares currents on both sides of a power transformer to detect faults. Solid state relays have no moving parts, allowing for high-speed operation. Electromechanical relays use a spring, armature, electromagnet and contacts to close the circuit when energized. Protection schemes use primary and backup relays, with primary relays clearing faults fastest and backup relays removing more of
This document discusses power electronics and drives, including AC converters and electrical drives. It covers inverters that convert DC to AC, including half-bridge and full-bridge single-phase inverters. It also discusses AC-AC converters like AC voltage controllers and cycloconverters. For electrical drives, it defines them, compares mechanical and electrical drives, and shows the basic block diagram of an electrical drive system including the power source, power modulator, motor, load, and control unit.
1. A chopper is a static device that converts a fixed DC input voltage to a variable DC output voltage directly through high-speed switching.
2. It operates by connecting the source to the load and disconnecting the load from the source at a fast rate, producing a chopped output voltage from a constant DC supply.
3. By varying the ON and OFF times of the switching semiconductor, the average output voltage can be controlled and varied as needed.
This document summarizes a study that compares the effectiveness of load tap-changing transformers (LTCT) and shunt capacitors for enhancing voltage profiles on Nigeria's 330kV, 24-bus transmission system. Load flow analysis was performed with and without each device. Results showed that with shunt capacitors, the algorithm converged in 5 iterations and total losses reduced by 4.1%, while with LTCT, convergence was in 4 iterations and losses reduced by 4.8%. Incorporating LTCT provided a better improvement to the voltage profile than shunt capacitors alone. The document provides background on voltage stability, LTCTs, shunt capacitors, the Newton-Raphson load flow technique, and how LTCT
This document summarizes a student project to design a buck converter circuit. Key details include:
1) The project aims to design a buck converter with an input of 10-15V and output of 5.5V ±0.5V capable of handling up to 2A.
2) The student describes their circuit design including a PWM generator using a 555 timer, comparator, and feedback controller to generate a switching signal for an IRF510 MOSFET.
3) Additional components include an inductor, capacitors, and a TIP32G transistor for current limiting. Test results showed the circuit outputting 5.52V across a 10Ω load with 43% efficiency from a 13.
1. Custom power devices condition power for medium-voltage distribution systems between 1-38kV and over 500kVA to protect entire facilities.
2. Static VAR compensators, static shunt compensators, and static series compensators are types of custom power devices that regulate voltage and compensate for reactive power.
3. Backup energy supply devices like battery UPSs, SMES, and flywheels provide temporary power during outages or disturbances until utility power is restored.
Measurement of Motion, Force
and Torque - Displacement and speed measurement for translational and rotation systems using
potentiometers, LVDT and RVDT, Encoders, accelerometers and gyroscopes. Force and Torque
measurements using strain gauges and piezoelectric pickups.
Review of Step down Converter with Efficient ZVS OperationIJRST Journal
This paper presents the review of step down converter with efficient ZVS operation. The designed buck converter uses ZCS technique and the function is realized so that the power form is converted from 12V DC 5V DC (1A). A detailed analysis of zero current switching buck converters is performed and a mathematical analysis of the mode of operation is also presented. In order to reduce the switching losses in associated with conventional converters; resonant inductor and resonant capacitor (LC resonant circuit) is applied which helps to turn on-off the switch at zero current. The dc-dc buck converter receives the energy from the input source, when the switch is turned-on. The buck–buck converters have characteristics that warrant a more detailed study. The buck converters under discontinuous conduction mode /continuous conduction mode boundary.
An autotransformer has a single winding that acts as both the primary and secondary winding. It connects portions of the same coil to act as both input and output rather than having separate windings like a typical transformer. This allows autotransformers to be smaller, lighter, and cheaper than equivalent dual-winding transformers but provides no electrical isolation between primary and secondary circuits. Autotransformers are commonly used in power applications to interconnect different voltage systems and for voltage regulation on long power distribution lines.
This document discusses various aspects of distribution systems including Kelvin's Law, AC and DC distributions, methods of voltage control and power factor improvement, distribution losses, types of substations, grounding techniques, and trends such as HVDC, FACTS, EHVAC transmission. HVDC transmission provides advantages over AC such as requiring less space, allowing ground return conductors, and providing asynchronous operation and controllable power flow. FACTS devices like TCSC, SVC, STATCOM, SSSC, and UPFC are used to control power flows and improve system stability and power transfer capability.
2 twofold mode series echoing dc dc converter for ample loadchelliah paramasivan
The document describes a dual-mode full-bridge series resonant DC-DC converter that can operate at either a variable switching frequency or a fixed switching frequency with phase-shifted pulse width modulation to regulate the output voltage over a wide range of loads. The converter uses a series resonant tank consisting of an inductor and capacitor to achieve soft switching and zero voltage switching of the transistors. It can operate in a frequency modulation mode at high loads by varying the switching frequency, or in a phase modulation mode at light loads using a fixed high switching frequency and varying the duty cycle through phase-shifted pulse width modulation. This dual-mode operation provides high conversion efficiency across a wide range of loads.
Chokeless welding transformer with load series motoreSAT Journals
Abstract
Welding is a materials-joining process that produces coalescence of materials by heating them to the welding temperature with or
without the application of pressure or by the application of pressure alone, and with or without filler metal. It is used to make
welds. It is observed that the welding transformer with choke or movable core is having large size, so to reduce the size we are
replacing the choke with one coil. This coil functions same as the choke. This coil helps to reduce the size as well as the cost of the
welding transformer. The forced air cooled transformer consists of an exhaust fan which rotates at a constant speed whether the
welding work is going or not. So, the more energy will be wasted there. To avoid this, the load series motor is used. The load
series motor as the name suggests is a motor, which is to be connected in series with a load. The load series motor, which shaded
pole motor but designed in such a way that if connected in series with load, it will run and speed of such motor will be
proportional to the load current. The ordinary exhaust fan motor can be, easily replaced by the load series motor.
Keywords: Rotary Switch, and Load Series Motor.
This document discusses switching transients in power systems. It covers:
1) Over voltages that occur due to switching operations like load switching and interrupting resistor current, and the equivalent circuits involved. Waveforms for transient voltages and currents are examined.
2) Current suppression techniques like current chopping to reduce switching transients. The effective equivalent circuit for current chopping is also discussed.
3) Capacitance switching and its effects. Topics covered include the impact of source regulation, and capacitance switching involving restrikes and multiple restrikes. Ferroresonance during capacitance switching is also illustrated.
The use of distributed generation (DG) within distribution systems has increased for the last two decades due to worldwide increase in demand for electricity and governmental policy change from “conventional” energy to “green” energy. High levels of penetration of DG have many significant benefits but also come with many drawbacks such as voltage drop and power losses. This study presents the impact of DG at different locations in a distribution feeder in terms of the feeder voltage profile. A radial distribution system is simulated using PSCAD/EMTDC simulation software while changing the size and location of DG in the system. The obtained results are used for better understanding on the impact of DG on voltage profile in radial distribution feeder.
Industrial Training in 2×3.14MVA 33/11 KV substation.rohitkashiv2020
### Overview of a 33/11KV Substation
A 33/11KV substation is a critical infrastructure in electrical power distribution systems, acting as a node where voltage levels are transformed from high to medium levels to facilitate safe and efficient distribution of electricity to residential, commercial, and industrial consumers. These substations are strategically located to optimize the distribution network and ensure reliable and stable power supply.
### Function and Importance
The primary function of a 33/11KV substation is to step down the voltage from 33KV to 11KV using transformers. This voltage transformation is essential because high voltage (33KV) is more efficient for transmitting power over long distances due to reduced losses, while lower voltage (11KV) is safer and more practical for local distribution.
#### Key Roles:
1. **Voltage Transformation**: The core function involves stepping down the voltage from 33KV to 11KV.
2. **Protection and Control**: It ensures the safe operation of the electrical network by incorporating various protection and control mechanisms.
3. **Power Distribution**: It serves as a distribution point to various feeders that supply power to different areas.
### Components of a 33/11KV Substation
A 33/11KV substation comprises several key components, each playing a vital role in the substation's operation:
#### Transformers
The main component of a substation is the transformer. A 33/11KV transformer typically has a capacity ranging from 5MVA to 40MVA, depending on the load requirements. These transformers are designed to handle the high voltage input and step it down to a manageable level.
#### Circuit Breakers
Circuit breakers are essential for protecting the substation and connected circuits from faults and overloads. At a 33/11KV substation, both 33KV and 11KV circuit breakers are used. These devices can quickly interrupt current flow in case of an abnormal condition, preventing damage to equipment and ensuring safety.
#### Isolators
Isolators are used to disconnect parts of the substation for maintenance and repair. They are not intended to interrupt load current but to ensure a section is de-energized for safe access.
#### Busbars
Busbars are conductors that serve as a central point for electricity distribution within the substation. They collect power from incoming lines and distribute it to outgoing feeders. The design and construction of busbars are crucial for maintaining the reliability and efficiency of the power distribution system.
#### Switchgear
Switchgear in a substation includes various switches, fuses, and relays that control and protect the electrical equipment. High voltage switchgear handles the 33KV input, while medium voltage switchgear manages the 11KV output. Modern substations use metal-clad or gas-insulated switchgear for enhanced safety and compact design.
#### Protective Relays
Protective relays monitor electrical parameters and trigger circuit breakers in case of faults
This document provides an overview of an industrial training seminar on a 33kV substation in Kamalwaganjha, Haldwani, Uttarakhand, India. The seminar covers the need for industrial training, an abstract of the substation, a single line diagram of the substation, details of main equipment including transformers, feeders, and testing procedures like tan delta testing. The goal is to enhance students' practical skills and introduce them to industrial practices through observing the key components and operations at a power substation.
Substations are facilities that receive power from generating stations and transmit it to consumers at varying voltage levels using transformers and other equipment. They allow for control of voltage, frequency, and power flow. Major substation equipment includes transformers, current and potential transformers, isolators, bus bars, circuit breakers, relays, and capacitor banks. Substations are classified by their application as generation, transmission, distribution, etc. Maintaining a high power factor is important for efficient power transmission, and capacitor banks can be used in substations for power factor correction.
Switching transients occur when a power system changes states, such as during load or capacitor switching. Resistance switching uses shunt resistors to limit overvoltage during current interruption. Load and capacitor switching can cause transient overvoltages due to the energizing or de-energizing of inductive and capacitive elements. Current suppression techniques like current chopping reduce inrush currents. Ferroresonance is a nonlinear resonance that can occur between a transformer's magnetizing branch and a capacitor, potentially causing sustained overvoltages.
This document discusses a dual mode series resonant DC-DC converter that can operate efficiently over a wide range of load variations. It presents a converter design that uses a full-bridge topology with series resonant components. The converter can operate in two modes - a switching frequency modulation mode for normal to high loads, and a phase shifted pulse width modulation mode for light loads. The dual mode operation allows for high conversion efficiency across the wide load range. Key aspects of the resonant converter design and operating principles are explained.
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
Sachpazis_Consolidation Settlement Calculation Program-The Python Code and th...Dr.Costas Sachpazis
Consolidation Settlement Calculation Program-The Python Code
By Professor Dr. Costas Sachpazis, Civil Engineer & Geologist
This program calculates the consolidation settlement for a foundation based on soil layer properties and foundation data. It allows users to input multiple soil layers and foundation characteristics to determine the total settlement.
This is an overview of my current metallic design and engineering knowledge base built up over my professional career and two MSc degrees : - MSc in Advanced Manufacturing Technology University of Portsmouth graduated 1st May 1998, and MSc in Aircraft Engineering Cranfield University graduated 8th June 2007.
MODULE 5 BIOLOGY FOR ENGINEERS TRENDS IN BIO ENGINEERING.pptx
Tap changer
1. A tap changer is a device fitted
to power transformers for
regulation of the output voltage
to required levels. This is
normally achieved by changing
the ratios of the transformers
on the system by altering the
number of turns in one winding
of the appropriate
transformer/s. Tap changers
offer variable control to keep
the supply voltage within the
limits. The 2 ½% step can be
2. Voltage regulation is normally achieved by changing
the ratios of the transformers on the system by altering
the number of turns in one winding of the appropriate
transformer/s. Tap changers offer variable control to
keep the supply voltage within these limits. Tap
changers can be on load or off load. On load tap
changers generally consist of a diverter switch and a
selector switch operating as a unit to effect transfer
current from one voltage tap to the next. Tap changers
can be adjusted to fit the application needs.
3. To supply a desired voltage to the load.
To counter the voltage drops due to loads.
To counter the input supply voltage changes on load.
Additionally required to perform the task of regulation of
active and reactive power flows.
4. Some form of impedance is present to
prevent short circuiting of the tapped
section.
A duplicate circuit is provided so that
the
load current can be carried by one circuit
whilst switching is being carried out on the
other.
5. Nominal Voltage set point.
Bandwidth (the amount of variation allowed before a
tap change
occurs).
Time delay (The amount of time the voltage must be
outside the
bandwidth before a tap change occurs) .
Line drop compensation ( a way vary the set point
voltage to
compensate for heavy loads)
6. Tap point is placed
In star connected winding, near the star point.
In delta connected winding, at the center of the windin
In autotransformer, between the series and common
7. Tap changers connected to the primary or
secondary side windings of the transformer
depending on:
Current rating of the transformer.
Insulation levels present.
Type of winding within the transformer (eg. Star, delta or
autotransformer).
Position of tap changer in the winding.
Losses associated with different tap changer configurations eg.
Coarse tap or
reverse winding.
Step voltage and circulating currents.
Cost.
Physical size.
8. No-Load Tap Changer (NLTC or
DETC)
On Load Tap Changer (OLTC
Mechanical tap changers
Thyristor-assisted tap changers
Solid state (thyristor) tap
changers
9. No-Load Tap Changer (NLTC or
DETC)In low power, low voltage transformers, the tap point can
take the form of a connection terminal, requiring a power lead to
be disconnected by hand and connected to the new terminal.
Since the different tap points are at different voltages, the two
connections can not be made simultaneously, as this would
short-circuit a number of turns in the winding and produce
excessive circulating current.
Mechanical tap
changers
A mechanical tap changer
physically makes the new
connection before releasing the
old using multiple tap selector
switches, but avoids creating
high circulating currents by
using a diverter switch to
10. Solid state (thyristor) tap changer
Recently developed which uses thyristors both to
switch the load current and to pass the load current in the
steady state. Their disadvantage is that all of the non-
conducting thyristors connected to the unselected taps still
dissipate power due to their leakage current.
Thyristor-assisted tap changers
Thyristor-assisted tap changers use thyristors to
take the on-load current while the main contacts change
over from one tap to the previous. This prevents arcing on
the main contacts and can lead to a longer service life.
11. On Load Tap Changer (OLTC)
OLTCs enable voltage regulation and/or phase shifting by
varying the transformer ratio under load without interruption. On
load tap changers generally consist of a diverter switch and a
selector switch operating as a unit to effect transfer current from
one voltage tap to the next. The selector selects the taps and is
operating in the transformer oil. The diverter is the actual switch
with high current contacts that balances the load from one tap to
the other. The divertor is inside a separate compartment inside the
transformer tank. The diverter and selector are positionned above
each-other and driven by the same axe. The voltage between the
taps is known as the step voltage, which normally lies between
0.8 % and 2.5 % of the rated voltage of the transformer.
Two switching principles have been used for load
transfer
operation :
1.the high-speed resistor-type OLTCs
2.the reactor-type OLTCs.
12. The resistor-type OLTCs are installed inside the transformer
tank (in-tank OLTCs)
The reactor-type OLTCs are in a separate compartment which
is normally welded to the transformer tank
13.
14. The OLTC changes the ratio of a transformer by adding or
subtracting to and turns from either the primary or the secondary
winding.
15. The “make before break contact concept”, is used. The transition
impedance in the form of a resistor or reactor consists of one or
more units that bridge adjacent taps for the purpose of transferring
load from one tap to the other without interruption or appreciable
change in the load current. At the same time they limit the
circulating current (IC ) for the period when both taps are used.
16.
17. Examples of commonly used winding
schemes
In star/wye connection, windings have
regulation applied to the neutral end.
18. Regulation of delta-connected windings requires a three-
phase OLTC whose three phases are insulated according
to the highest system voltage applied.
Today, the design limit for three-phase OLTCs with phase-
to-phase insulation is the highest voltage for equipment of
145 kV.
To reduce the phase-to-phase stresses on the delta-
OLTC the three pole mid-winding arrangement (fig. 7 c)
can be used.
19. For regulated autotransformers, the most appropriate
scheme is chosen with
regard to regulating range, system conditions and/or
requirements, as well as weight and size restrictions during
transportation. Autotransformers are always wye-connected.
20. The switching capacity itself is primarily a function of the
contact design, contact speed and arc-quenching agent.
Based on that OLTC are of two type:
1. Oil-type OLTCs
2. Vacuum-type OLTCs
Resistor oil-type OLTCs
In an oil-type OLTC, the OLTC is immersed in
transformer oil and switching contacts make and break
current under oil.
For higher ratings and higher voltages comprises a
diverter switch (arcing switch) and a tap selector.
For lower ratings, OLTC designs in which the functions of
the diverter switch (arcing switch) and the tap selector are
21. 1. With a diverter switch & a tap selector operation takes place in t
a. The next is preselected by the tap selector at no load.
b. The diverter switch then transfers the load current from the tap
operation to the preselected tap.
The OLTC is operated by means of a drive mechanism.
Switching time of a divertor switch is b/w 40 &60 ms.
Transition resistor are inserted which are loaded for 20-30 ms.
Total operation time 3-1o sec.
2. A selector switch(arcing tap switch) carries out the tap in one ste
tap in service to the adjacent tap
22.
23. Reactor oil-type OLTCs
The following types of switching are used for reactor oil-
type OLTCs:
1. Selector switch (arcing tap switch)
2. Diverter switch (arcing switch) with tap selector
24.
25.
26.
27. Technical features
The vacuum interrupter is a hermetically-sealed system.
There is no interaction with the surrounding medium, despite the arc.
The switching characteristics do not depend on the surrounding medium.
Low energy consumption.
Reduced contact wear.
Elimination of the insulating medium as the arc quenching agent.
Elimination of by-products e. g. carbon when using transformer oil.
On-line filter is unnecessary.
Easy disposal.
No aging of the quenching medium.
Constant or even improving switching characteristics throughout the entire
lifespan of the
vacuum interrupters (getter effect).
No interaction/oxidation during switching.
High rate of recondensation of metal vapour on contacts extends contact
life.
Constantly low contact resistance.
Extraordinary fast dielectric recovery of up to 10 kV/µs.
Ensures short arcing times (maximum one halfcycle) even in the case of
28.
29.
30. To select the appropriate OLTC, the following key data
of the corresponding transformer windings should be
known:
MVA rating.
Connection of tap winding (for wye, delta or singlephase
connection).
Rated voltage and regulating range.
Number of service tap positions.
Insulation level to ground.
Lightning impulse and power frequency voltage of internal
insulation.
The following OLTC operating data may be derived
from this information:
Rated through-current: Iu
31. The appropriate tap-changer can be
determined:
OLTC type
Number of poles
Nominal voltage level of OLTC
Tap selector size/insulation level
Basic connection diagram
32. During the operation of the diverter switch (arcing switch)
from the end of the tap winding to the end of the coarse
winding and vice versa, all turns of the whole tap winding and
coarse winding are inserted in the circuit.
This results in a leakage impedance value which is
substantially higher than during operation within the tap
winding where only negligible leakage impedance of one step
is relevant. The higher impedance value in series with the
transition resistors has an effect on the circulating current
which is flowing in the opposite direction through coarse
winding and tap winding during diverter switch operation.
Consequently a phase shift between switched current and
recovery voltage takes place at the transition contacts of the
diverter switch and may result in an extended arcing time.
In order to ensure optimal selection, it is necessary to
33.
34.
35.
36.
37.
38. Reduction of power losses
Voltage profile enhancement
Voltage stability
The tap changing transformer is connected at the load terminal, its
tap ratio is ‘t’. Transformer reactance at unity off-nominal tap ratio
The approximate voltage drop formula is
System voltages and impedance referred to the system load side a
respectively
39.
40. Voltage value of sec. terminal of transformer can be
regulated using tap changer. This regulation also affects
the calculation of the thevenin equivalent parameters.
Changes of equivalent parameters cause a change of
voltage stability conditions.
41. In the radial distribution system, each radial feeder is
divided into load sections with a tap changing transformer at
the beginning of the distribution network. However, there is the
need to find the tap setting of the substation transformer that
would give minimum distribution loss while satisfying the
operating constraints under a certain load pattern. These
operating constraints are voltage drop, current capacity and
radial operating structure of the system. The mathematical
formulation for the minimization of power loss tap changer
problems is