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Tan delta test, also known as dielectric dissipation factor test is a critical diagnostic test, which is used to assess the insulation health of high voltage electrical equipment such as transformer, bushings, cables, rotating machines and instrument transformers. The tan delta test measures the dielectric losses that occurs …
The winding resistance test is the fundamental diagnostic test which is performed on power transformer in order to access the electrical integrity of the transformer winding, joints and tap changer (OLTC) contacts. By measuring the DC resistance of each winding and comparing it to the factory tests or …
Transformer turns ratio test is a diagnostic and acceptance test which is performed to verify the correctness of transformer’s winding ratio with the designed value and the vector group. Transformer turns ratio test verifies that the primary to secondary turns ratio is correct and ensures that the transformer …
Contact resistance measurement is an important diagnostic test which is used to access the condition and performance of electrical contacts in substation or power station equipment such as circuit breaker, isolator, bus bar joints, and various other connectors. The contact resistance measurement is performed using a low resistance …
Fall of potential test is a field method used to determine the earth resistance of the grounding system of substations, power plants, and transmission line structures. The fall of potential test is based on the principle of measuring the voltage drop in soil caused by injecting known test …
Battery energy storage system is a critical asset to modern power system because it addresses the growing need for flexibility, reliability and efficient energy management. In electrical grids with high intermittent renewable energy integration like solar or wind makes the conventional generation no longer sufficient to maintain voltage …
Pumped storage hydropower is basically a large-scale energy storage technology which is used to balance the generation and demand in the power system. The basic idea of pumped storage hydropower is to raise the potential energy of the water by pumping action from a low reservoir to high …
Dielectric loss in capacitor bank refers to the dissipation of real power in the insulating dielectric material of the capacitors, when it is energised with AC voltage. The dielectric loss in capacitor bank is quantified by the loss angle δ or commonly by tan δ, which is the …
Harmonic mitigation is a critical requirement in modern power system because of rapid penetration of power electronics, nonlinear loads and converter-based systems. Harmonic mitigation focuses on limiting the generation of harmonics, controlling the propagation, and protecting the system assets from the adverse effects of harmonics. This is achieved …
Harmonics are unwanted components of frequency present in voltage or current that are integer multiple of the fundamental frequency. In practical power system, voltage and current waveform are not always perfectly sinusoidal as it contains multiple frequency components in addition to the fundamental. These additional frequency components are …
A STATCOM or static Synchronous Compensator is a fast acting device used in power system, which regulates the voltage, provides control over reactive power and enhances the stability of the grid. STATCOM employs a voltage source converter with solid state switches to generate or absorb the reactive power …
A static var compensator is a high speed, power electronic based reactive power control device which is designed to regulate voltage and improve power quality in transmission and distribution networks. The static var compensators are installed at substation or critical grid nodes to dynamically adjust the reactive power …
Battery sizing is a critical engineering process which is used to determine the required capacity of a battery system, which has to ensure uninterrupted power supply to protection system, control system and communication equipment of the substation during normal and emergency operating conditions. The battery system must support …
Battery management system is a specialized electronic control system, which supervises the operation of rechargeable batteries by monitoring, protecting balancing and thus optimizing the performance and safety of the battery system. The battery management system acts as the brain offering intelligence to the lead acid battery or lithium …
Substation battery chargers are vital component of the substation DC system. The substation battery charger is responsible for providing continuous and reliable DC power for the protection system, the control system and communication equipment available at the substation. Unlike the AC system, which is grid dependent, the DC …
Lithium ion battery, today are not limited to smart phones and laptops only, they forms a critical part of the modern power infrastructure, supporting the renewable energy plant to large scale power grids and high reliability substations. Earlier the power system was depended upon diesel generators, lead acid …
Lead acid battery is a mature rechargeable electrochemical energy storage technology, which was first used in the year 1859. Lead acid battery finds its application in many industrial and stationary backup power environment like substation, where cost, reliability and high surge capability are the priority. In the power …
Nickel Cadmium battery is among the most reliable and oldest rechargeable battery technologies that is still in use. The Nickel Cadmium battery technology developed in 1899, is still in use for critical power systems like substation, telecom facilities, and control systems. The Nickel Cadmium battery remains operational under …
An autotransformer is a special type of transformer, which has a single continuous winding which performs the function of both the primary and secondary windings. A conventional transformer uses two electrically isolated windings for input and output but an autotransformer uses common turns for both input and output. …
The Nitrogen Injection Fire Protection System, NIFPS is a dedicated safety system for oil filled power transformers, which is capable of preventing catastrophic fire and explosion during severe internal electrical faults. The NIFPS system operates rapidly by draining the hot oil, isolating the conservator tank, and injecting high …
The magnetic core of the transformer is the fundamental working element which is responsible for provision of low reluctance path for the magnetic flux, enabling efficient energy transfer between the primary and the secondary windings of the transformer. The magnetic core design of the transformer directly influences the …
The conservator tank is an auxiliary oil reservoir to the main tank of the transformer. The conservator tank is mounted above the main tank of the transformer and is connected to it via a pipe. The primary function of the conservator tank is to accommodate expansion and contraction …
A power transformer is basically a static device which is used to transfer bulk electrical energy from one circuit to another with the help of electromagnetic induction. The primary purpose of power transformer is to alter the voltage level of the electrical energy source by either stepping up …
Head end system is the central server platform within the advanced metering infrastructure which controls the central communication and interfaces directly with filed devices and data concentrator units. The HES in the AMI is responsible for establishing communication session with smart meters, collecting the raw meter data, sending …
A metering error is basically the difference between measured value and the true value or actual value of the quantity being measured. It represents the failure of the meter or associated system to accurately detect or record the electrical parameters. In mathematical terms, a simple metering error is …
A disturbance recorder is a component of the digital fault recorder installed inside the intelligent electronic devices IEDs of the substation. It is used to capture high resolution electrical waveforms and digital status of various components connected to the system, time stamped during transient events or abnormal conditions …
Power quality analysis fundamentally means the measurement and evaluation of disturbance in the power system in order to implement changes for having a stable and consistent power flow allowing all connected equipment operate reliably and efficiently. Power quality analysis is essential because low quality power with interruptions, fluctuations …
AMI or Advanced Metering Infrastructure is a system of metering, which is incorporated of smart meters, communication networks and data management systems that enable two way communication between the power utility and consumers. AMI is the digital backbone which pushes the utility’s operation to the end point of …
In context to DLMS?COSEM, DLMS stands for Device Language Message Specification and COSEM stands for Companion Specification for Energy Metering. The set of specifications for the standard for global smart metering and data exchange is defined by DLMS/COSEM. It is a two part framework which makes sure that …
The optical port of energy meter is basically a non contact type communication interface, which uses infrared light signals to transfer data between the meter and an external device via a probe or optical head. The energy meter’s casing has an in built infrared LED transmitter and an …
ABT meter is a specialized electronic energy meter that works on Availability Based Tariff system. Other than precisely monitoring and recording the energy consumption, it measures the energy consumption in the four power quadrants and thus is a bidirectional meter. What is Availability based tariff mechanism? The availability …
Accuracy class of energy meter actually indicates the maximum possible error that is acceptable in the measurement of energy consumption. Essentially it means how precisely the measured value agrees to the true value of energy consumption under various working conditions. The maximum possible error in context to accuracy …
Metering analytics is the process of analysing massive amount of data collected and processed by the smart meters and advanced metering infrastructure. Metering analytics uses software, algorithm and machine learning models, which transforms the data from the meters into some actionable intelligence. The main objective of metering analytics …
A power quality meter is a special type, high speed digital device that is used for precise measurement and record of electrical disturbances and waveform abnormalities in the electrical system. Power quality meters capture and analyses the transient events, voltage sag or voltage swell, unbalance and harmonics in …
Net metering meter is usually a bidirectional meter, which is used in grid substations, grid connected roof top solar systems and likewise installations where energy is imported as well as exported. The net energy meter is installed to measure the imported KWh and the exported KWh, while it …
A TOD meter or Time of Day meter is a type of energy meter that not only records the energy consumption but also records the time of consumption. Other than displaying the total KWh consumed, the TOD meter splits the energy usage into different time blocks such as …
A trivector meter is a three phase energy meter that measures the three vectors of power namely active (KW), reactive (KVAR) and apparent (KVA) and integrates over the time to compute the active, reactive and apparent energy. Trivector meter also measures the power factor and maximum demand integrated …
A maximum demand meter is a special type of meter used by the utilities to measure the highest average power demand in KW or KVA that is drawn by a consumer during a specific time interval or repeating blocks (15 minutes/ 30 minutes/ 1hour). Along with the measurement …
A single phase meter is used in homes, small commercial shops and lightly loaded installation that accurately measures the electrical energy consumption in a 230 V or 120 V, two wire systems (phase and neutral). It’s basic job is to record every unit of electricity drawn so that …
Soil resistivity is the foundation of every grounding and earthing design. Determination of how easily the fault current dissipates into the earth, depends directly on the soil resistivity. It influences the size of the earthing grid, step and touch potentials and overall safety of the project. A well …
Generator grounding is basically connecting the generator’s neutral point to the earth in a controlled manner so that the fault current has a path to flow. Unlike normal system grounding, the generator needs own dedicated grounding because its behaviour during the faults is different from transformers as the …
Equipment grounding is a process of connecting all non-current carrying metallic parts like panels, equipment enclosure, motor, cable trays and various structures together and eventually to the neutral ground bonding point through a low impedance path, ensuring all metal parts remains at same potential. Every electrical installation depends …
System grounding is basically a process of connecting the neutral of the power system (generator, transformer or network) to the earth. Either solid connection or resistive or reactive or left ungrounded, it is this choice that determines the behavior of the system during faults. The magnitude of the …
The Grounding electrode conductor is the most essential part, that forms the backbone of any grounding system because it forms the main low impedance path through which the fault current and lightning energy gets safely dissipated to the earth. Without the grounding electrode conductor even the best of …
Electrode grounding is the method of connecting an electrical installation to the ground using a buried electrode, which can be a rod, plate, pipe or ground ring, for safely dissipating large fault currents. The main purpose of the electrode grounding is to safely dispose off the fault current, …
A ground ring electrode is basically a closed loop electrical conductor (mostly copper) buried around the perimeter of an electrical installation like a building, a substation or a equipment area. It forms a continuous low resistant path for the fault current to flow to the earth with uniform …
Earthing layers are basically layers of conductive materials like charcoal, bentonite, sand, and salt or any special backfill compound, which is placed around the electrode in order to improve the soil conductivity. It is the earthing layer which is responsible for uniform and low resistance interface between the …
An earthing point is the physical point where the electrical installation connects to the earth using an electrode, earthing conductor or busbar. In installation such as a substation, industries, panel boards in control room are often connected to the earthing electrode via common bus bar. The earthing point …
Grounding vs bonding is a very important topic for discussion as both deals with the connection of electrical system for creating a safe path for the fault current yet serve different purposes. Grounding connects equipment or system to the earth in order to stabilize the voltage and provide …
AAC conductor or All Aluminium Conductor is basically a stranded conductor that is made up of hard drawn aluminium wires. AAC conductors finds wide application in the power distribution networks, with shorter pole span, high conductivity and reduced line loss becomes the priority. All Aluminium Conductor is a …
A fiber optic cable (FO cable) is a medium of high speed data transmission is made as information is carried by the pulses of light through thin strands of glass or plastic fibers. Unlike the copper cables which transmits electrical signals, the fiber optic cable (FO cable) uses …
ABC cable or (Aerial Bundled Cable) is basically an overhead distribution cable system, which consists of insulated phase conductors, bundled together with a bare or in some cases insulated neutral messenger. The use of ABC cables has an improved safety, reduced electrical fault from foreign object contact as …
DC cables are special type of power cable which are designed for the reliable transmission of direct current with minimal drop in voltage and thermal energy loss. Unlike AC cables, the DC cables do not have the skin effect, capacitive or inductive reactance, thus making the utilization of …
Control cables are multi core cables ( 2 core or more), specially designed to transmit low voltage signals for the monitoring, protection, industrial automation and control of electrical equipment. In power system, control cable connects various relays, circuit breaker, switchgear, transformer and SCADA devices to ensure protection, operation …
Coaxial cables are special electrical cable which are designed for carrying high frequency signals with minimum loss and also protect the signal against noise. The Coaxial cable contains a central conductor with a dielectric layer of insulation, metallic shield that is braided or with foil and an outer …
Cable joint is a process of connecting two or more electrical cable for extending the length and form a continuous electrical circuit. The main purpose of cable joints is to maintain efficient electrical continuity along with good mechanical strength without affecting the insulation integrity across the cable’s connection. …
PILC cables (Paper Insulated Lead Covered) are cables that has been used in the power industry, traditionally. PILC cables had a wide application in medium voltage power transmission and distribution system. These cables has oil impregnated paper insulation which is enclosed in lead sheath, resulting in excellent moisture …
PVC cable (polyvinyl chloride) is widely used cable insulation and sheath material since 1940s for its excellent durability, flexibility and cost effective solution. PVC cables offers very good electrical insulation while providing the required mechanical strength, resistance to moisture, chemical and abrasion, making its application, suitable in harsh …
XLPE cables (Cross-Linked Polyethylene) are power cables which uses cross-Linked polyethylene as the cable’s insulation for an enhancement in thermal, electrical and mechanical properties. This technology in power cable developed in the late 1950s as an improvement over the existing PVC and the paper insulated cables. XLPE cables …
AAAC conductor (All Aluminium Alloy Conductor) is basically an electrical conductor, which is entirely made up of an aluminium-magnesium-silicon (Al-Mg-Si) alloy. The Aluminium provides excellent electrical conductivity of around 53% of IACS (International Annealed Copper Standard) and low weight because of its low density, making it efficient for …
An ACSR conductor (Aluminium Conductor Steel Reinforced) is a composite, stranded conductor which finds wide application in the overhead transmission line. The outer section of ACSR conductor is basically made of stranded aluminium wires which provides excellent electrical conductivity with the steel core enhancing the overall mechanical strength …
A solid state relay is basically a switching device that has electronic components like thyristors, TRIACs or transistors for achieving the control of electrical loads without moving parts. It functions similar to an electromechanical relay but with faster switching, longer lifespan and higher reliability in zones of vibrations. …
Earth switch in electrical system is used for the personnel protection during the maintenance of the component of the system. It is among the most important component for the maintenance and is also known as grounding switch. Earth switch enables the residual or induced electrical charge to dissipate …
Various circuit breaker types play a pivotal role in various types of electrical circuit based on complexity and other selection criteria, intended for protection of the circuit from overloads and short circuit faults. These devices automatically interrupts the electrical circuit, preventing the connected equipment damage. The circuit breaker …
In context of circuit breaker vs fuse, overcurrent protection provides safety cushion to electrical circuits from excess current flow in the circuit, caused by short circuit, or overload thus increasing system reliability and preventing equipment damage in the electrical installation. Protective devices interrupts the fault instantly as it …
A Ground Fault Circuit Interrupter (GFCI) is that circuit breaker which instantly acts to interrupt the power in a circuit, when it detects an imbalance between the incoming and outgoing current, which indicates a ground fault. This type of circuit breaker prevents electrical shock and fires which otherwise …
A proper understanding of switchgear vs switchboard is essential in the design of modern power system as both Switchgear and switchboard are central components to the electrical power transmission and distribution system as they provide the necessary control, protection of circuits and the isolation. Switchgear includes circuit breaker, …
Circuit breaker sizes basically refers to the current rating (ampere) that it can safely conduct without tripping during normal operation. It refers to the maximum continuous current carrying capacity of a circuit breaker without causing interruption in the power flow of the circuit preventing any sort of overheating …
In order to learn how to wire a main breaker panel, it is essential to understand what a main breaker panel is? A main breaker panel or service panel or distribution panel is a junction through which the utility power enters a facility and is distributed to different …
Residual current device is a device used in electrical circuits which protects humans from electrical shock and electrical fire as well which may be caused because of current leakage. The device is placed between the phase and neutral wire for monitoring and detection of any unbalance in current …
An Electrical Fuse is a basic protection device which helps with protection of the circuit from overcurrent. Overcurrent in any electrical system is the flow of excessive current, higher than the rated current of the circuit. Overcurrent protection in any electrical system thereby detects and interrupts the excess …
A circuit breaker keeps tripping is a frustrating problem for everyone without any apparent reason. After the reset of the circuit breaker, the power flows into the circuit, but soon it trips. It’s true, the issue annoys everyone, but in reality, the circuit breaker is only operating to …
Knowing how to reset a circuit breaker is though underrated but still essential skill in daily life. Circuit breakers are used in an electrical circuit to make or break the circuit. After the break of the circuit, electrical isolation of the circuit is achieved. It protects the circuit …
AFCI circuit breaker, or arc fault circuit interrupter, is a special type of circuit breaker that is engineered to sense and interrupt dangerous electrical arcs and associated faults in the circuit before a fire hazard occurs. It is usually installed in the electrical panel, which protects the electrical …
Circuit breaker replacement is a critical process and must be done by an experienced person. As we know that the circuit breaker is an essential equipment that protects the circuit from overcurrent and overloading conditions in the circuit. Hence, when the circuit breaker goes bad, circuit breaker replacement …
How to tell if a circuit breaker is bad is an essential trait for not only industrial experts but also every person to know for protecting his/her home and electrical appliances from fire hazard. A circuit breaker is a very important equipment in domestic as well as industrial …
The SF6 Circuit breaker is a compact device that uses sulfur hexafluoride gas to quench the arc during its operation, i.e, to break or make a medium to high voltage electric circuit. Along with the protection system employed in the circuit, this circuit breaker operates, and the contacts …
Data center substation is among the special types of substations, which are specially designed for highly reliable, high power quality, and uninterrupted power supply to critical IT processes in the data center. These substations stress majorly on the importance of redundancy of power supply with reliability to various …
A substation technician is a skilled professional who helps the engineer with the installation, testing, operation, and maintenance of the substation equipment. The substation technician, along with the engineer, makes sure that the substation operates efficiently and reliably. The critical substation equipment requires continuous monitoring, such as the …
A single-line diagram or substation SLD represents three phases of a power system by a single line, showing the arrangements of different electrical equipment in the switchyard. It shows how the generator, transmission line, circuit breaker, wave trap, capacitive voltage transformers, current transformers, etc, are interconnected with the …
An Electric substation is a part of the power system, which is utilized mainly for the transformation of voltage, either stepping up or down, depending upon the type of substation, either a generation substation or a transmission substation, respectively. Main electrical equipment of a substation The main electrical …
Substation SCADA (Supervisory Control and Data Acquisition) is basically a system of certain hardware and software through which monitoring, analysis, and control of a power system can be achieved remotely. The data is acquired from the field equipment, transmitted to a central unit utilizing a communication network, which …
Renewable energy integration in a substation is the process of connecting the renewable energy-generating plants, like solar, wind, hydro, and biomass plants, to the electrical grid for the transformation and transmission of generated power. The renewable energy integration of the substation also refers to the substation being the …
A digital substation is a modern electrical substation, where the use of copper cable for communication between various conventional relays is minimal; rather, optical fiber is used for communication between circuit breakers, transformers, and IEDs (Intelligent Electronic Devices). The raw electrical signals used in older substations are replaced …
A mobile substation is a temporary arrangement of compact assembly of all the essential components of a power distribution system, mounted on a transportable platform. The setup of this type of substation is easy and quick, done primarily to provide emergency power to areas that cannot be conventionally …
Substation construction is the building of an electrical substation, which is an essential part of a power system that connects the transmission network to the distribution network or generation to the transmission network. Substation construction involves civil works for the foundation of various electrical equipment and the control …
Creepage distance is the minimum distance between two conductors (phase to earth or phase to phase) along the surface of the separating insulator. It is the surface leakage path that the leakage current will take across the insulator via its surface and not through air. As the path …
Insulation coordination is basically the selection of the dielectric strength of the equipment with respect to the operating voltage and the overvoltage stress it will be subjected to during the system operation, considering the environment and characteristics of protective devices. The objective of insulation coordination is to increase …
The minimum distance or gap that is required between two conducting parts, without causing any electrical flashover, is known as electrical clearance. Electrical clearance is a function of the implied voltage or potential difference between the two conductors. If the voltage between two conductors is more, then the …
Substation Layout is basically an orderly arrangement of electrical equipment based on function, safety, and security, considering several clearances and space constraints or availability of land for achieving better operational flexibility, security of power supply, maintenance flexibility, along with accounting for lower cost. A well-designed Substation layout offers …
A turnkey project involves a single contractor or EPC firm engaged for the entire project life-cycle, responsible for engineering design to construction, procurement, and commissioning, finally handing over to the asset owner as a ready-to-use facility. Here, the asset owner usually turns the key to start the operation. …
The Rankine Cycle comprises of 4 thermodynamic processes on which the steam engine or turbine is based to convert the heat energy into mechanical work. It is also the ideal vapour cycle which is used for comparing the performance of various power generating plants running on steam. Basic …
The Carnot cycle is the thermodynamic power cycle that was introduced by a French military Engineer, Nicolas Léonard Sadi Carnot in the year 1824 in his work, “reflection on motive power of fire”. It is a theoretical power cycle which is reversible with conserved entropy. Working The Carnot …
Parallel operation of the transformer is a method of operating two or more transformers that are primarily connected to a common source and whose secondary sides cater to a common load such that the load is shared between the connected transformers. Parallel operation of the transformers is considered …
A synchronous condenser is an electrical machine, used in the substations for absorbing or supplying reactive power by controlling the excitation of the machine, thus making the grid stable and also regulate the voltage levels. Working Principle of synchronous condenser The synchronous condenser works like a synchronous motor …
Reactive power, in an AC circuit, is the rate of energy that flows in and out of inductive and capacitive elements. As these elements result in a phase difference between voltage and current, causing the energy to be alternately stored and released in the respective electric and magnetic …
Frequency meters are instruments that are widely used for the measurement of the frequency in various power system applications. Frequency is a very critical parameter in the electrical system as system stability, equipment performance, grid reliability, power quality, and economic efficiency all depend heavily on system frequency. Hence …
A flexible AC Transmission system includes the use of power electronics for controlling the voltage and the power flow of the AC transmission system. The power electronics include controlled shunt and series reactive power such as static Var compensator, static compensator (STATCOM), Thyristor controlled series compensation system (TCSC) …
The dissolved gas analysis of a transformer also called transformer gas analysis is an essential process or technique through which the condition of the transformer and its life expectancy can be calculated. Periodic dissolved gas analysis or DGA test can forecast the faults present in the oil-insulated electrical …
Air blast circuit breakers are a fast operating circuit breaker in which the quenching of the arc is achieved by a blast of compressed air inside the interrupter chamber. These breakers are mainly used for high-voltage applications because of their high speed operation. These breakers are suited for …
VRLA battery or valve-regulated lead acid is a type of lead acid battery that promotes minimum to no water addition maintenance, sealed in a structure with no acid leaks and no mists. It has a one-way valve to allow the escape of gas formed inside above a predetermined …
Vacuum circuit breakers uses high vacuum inside the interrupter unit as a dielectric media for suspension of the arc that is generated on contact separation. Vacuum has a very high dielectric strength in the range 106 -108 Volts/meter with excellent arc quenching characteristics. At high vacuum inside the …
The high voltage DC power line transmission is a system in which the bulk power is transmitted over long distances using direct current at a much-elevated voltage level. For long-distance transmission, the conventional AC system incurs various power losses making it an expensive mode of transmission. However, high …
Electrical continuity essentially means that there exists a conductive part, through which electricity can flow sufficiently. Electrical continuity can present itself in the insulated electrical part making it unsafe for further operation or is a much-needed aspect for the conductors for efficient propagation of electricity into any circuit. …
A smart meter is an electronic device that keeps a record of energy consumption, and electrical parameters like voltage levels, current, power factor, etc. These meters have a built-in communication channel through which it can communicate both ways between the meter and a central system. This communication can …
An uninterruptible power supply or UPS is a much-needed system for catering reliable, uninterrupted, high-quality power to vital loads such as data centers, critical health care support equipment, domestic equipment, and many more. Uninterruptable power supply is mostly a backup to the main power source from the utility …
Air Circuit Breaker (ACB) Air circuit breaker is the simplest form of circuit breaker. In this circuit breaker, the interruption of the arc is achieved by the natural deionization of gases by cooling. The arc is also lengthened for its resistance to get increased so that the source …
Design Parameters for EARTHMAT DESIGN 132 KV Reference Standard IEEE – 80 – 2000 Resistivity Data for EARTHMAT DESIGN 132 KV SS Soil Resistivity, ρ = 90 Ω m Surface layer resistivity, ρs = 3000 Ω m Surface layer thickness, hs=0.10 m Reflection factor between different resistivities …
Thermographic inspection Thermographic inspection is a nondestructive testing method, part of the maintenance schedule that is applied in different sectors. The power sector is one of them, and its use is quite widespread. It is applied to all types of facilities and voltage levels. Although, thermographic inspection points …
Requirement for a Tower Grounding Device The transmission tower grounding devices basically conducts the direct lightning current and power-frequency short-circuit currents efficiently into the earth. They are critical components which ensures the safety of persons around the towers as they hold certain lightning protection levels. The impulse impedance …
Methods for decreasing grounding resistance Decreasing grounding resistance of a system can efficiently bring down the ground potential rise which is fault current multiplied by the grounding resistance. Thus it makes the site safer during faults. Decreasing grounding resistance also makes the transfer potential lower, which is the …
Fault Current Division Factor During a local or remote earth fault in the substation, the fault current reaches the neutral of the power system via the earth. Part of this fault current flows to the earth from the earthing grid, the ratio between the portion of fault current …
Decrement Factor for grounding design Decrement factor Df is basically the ratio between the rms value of the asymmetrical fault current to the symmetrical grounding fault current. IG is the maximum asymmetrical alternating current flowing from the grounding grid to the surrounding earth, which includes the rms symmetric …
Principle to Determine Maximum Grounding Grid Current The maximum grounding grid current, IG is the maximum fault current that flows into the earth from the grounding grid for an internal fault at the substation or vice-versa for any external remote fault outside the substation. It is the most …
Data Required for the Design of Earth Mat of a Substation (i) Soil resistivity model for the site of the substation or soil resistivity test data where earth grid or earth mat has to be constructed. (ii) Electrical circuit single line diagram for the station where earth grid …
Safety Clearances The “safety clearance” is the minimum distance in air which is to be maintained between a live conductor and earth, or other equipment on which work has to be carried out. There are many different values of safety clearances used by various utilities around the world. …
Site Selection of a Grid Substation The site selection of a Grid Substation is the first and most important activity. This needs meticulous planning, foresight, skillful observation, and handling so that the selected site is technically, environmentally, economically, and socially optimal and is the best suited to the …
Arrangement for capacitor bank can be configured based on available voltage levels, protection phillosophy and required relaibility and flexibility of use. Most substations uses a star connected bank, however distribution units may be star or delta connected. Some system uses H arrangement in the units per phase of …
Shunt capacitor Banks Shunt capacitor Banks or SCBs are used in the power system as they deliver capacitive reactive power compensation that aids in improving power factor. These capacitor banks are easy to install and maintain providing an affordable and simple solution to power factor correction needs. Other …
Leakage Resistance of a Capacitor The resistance of the dielectric of the capacitor is called the leakage resistance of a capacitor. The dielectric medium in the ideal capacitor is considered a perfect insulator (i.e., it has infinite resistance), with zero current flowing through it when a potential difference …
In general, the electrical resistance of a material changes with the change in temperature. The effect of temperature on resistance varies according to the type of material as discussed below EFFECT OF TEMPERATURE ON RESISTANCE OF PURE METALS The effect of temperature on resistance is such that the …
The CT core sizing depends on the relay consideration for the feeder protection. FOR METERING CT CORE SIZING: The CT can be a multi-radio CT and the turns ratio or CTR can be calculated based on the estimated load/demand/requirement in the feeder. Also to take into consideration the …
The relay selection for transmission line protection utilizes one of the two major relaying philosophies. One is distance protection and the other is differential protection. Both of these protection philosophies are discussed in detail in previous posts. The other relays such as an overcurrent and earth fault relay …
PROTECTION CORE OF CT It is known that current transformers are used for protection and metering purposes. A current transformer or CT can have more than one core in the case of a multi-core CT that is normally used in power stations. One is used for metering purposes, …
INSTRUMENT SECURITY FACTOR OF CT Instrument security factor, ISF is the times of rated current above which the CT metering core will saturate. The ratio of the saturating primary current to the CT-rated current is known as the Instrument security factor. The multi-functioning meters or energy meters connected …
The burden of current transformer is basically the apparent power that is consumed at the secondary side at a specific power factor, rated secondary voltage, and current. It is because of the impedance/ admittance at the secondary circuit expressed in Siemens or ohm and power factor. Unlike a …
The accuracy class of Current Transformers used in the industry is designated by the highest permissible percentage ratio error at rated primary current and rated output. The RATIO ERROR in the accuracy class of current transformer The ratio error plays a major role in determining the accuracy class …
SIGNIFICANCE OF CT POLARITY Current transformer polarity is the direction of current in the secondary winding in relation to the primary current. It is often marked by square markings or P1 and P2. The polarity of the CT connection is of utmost importance in substation protection as the …
Step potential and touch potential are very essential factors in the designing of the earthing system of any substation. Step potential and touch potential also decide the overall safety of personnel working in the substation. As for humans, 25mA current can prove fatal hence calculation of step potential …
CONDUCTOR SIZING WITH IEEE-605 We have already discussed the busbar and the conductors in the previous articles. Now the essential part is to know how the conductor sizing is done for the main busbar of any substation. To explain this, we shall take the example of a 132KV …
Cable laying is a very essential part of any electrical installation. It helps optimize the power flow, reduces electromagnetic interferences on control cables, reduces fire risks, etc. MINIMUM PERMISSIBLE BENDING RADII OF CABLE LAYING. The electrical power cables should not be bent in a very sharp radius in …
CABLE SELECTION CRITERIA The design is based on a minimum of three factors: Short circuit current rating: It is the most important part of the cable selection criteria. It basically is the maximum current that the cable has to handle in case of a fault until the fault …
KNEE POINT TEMPERATURE The temperature at which the envelope of a conductor becomes mechanically unloaded is called knee point temperature. When the temperature of a composite conductor is increased, the aluminium (or aluminium alloy) envelope wires undergoes more expansion than the core does. This expansion results in reduction …
DIFFERENT TYPES OF HTLS CONDUCTORS High temperature low sag, htls conductors are modern conductors with enhanced thermal sag properties. Their maximum continous operating temperature is also increased, which aids in the conductor’s high current carrying capacity and also optimizing transmission network of a region. These high performance conductors …
POWER CONDUCTORS Power Conductors are the most essential part of the transmission and distribution of electricity. It is the medium via which the current flows. Normally it is made of copper or aluminium alloy as these metals have proven good service and have less resistivity and cost. TYPES …
POWER CLAMPS Electrical energy flows through many equipment and various lines to reach the end consumer or load. In this process, it requires many terminations of conductors to all the equipment it passes through. This termination is made possible through the use of various clamps and connectors that …
KNEE POINT VOLTAGE OF A CURRENT TRANSFORMER As we know from our previous discussions the function of a current transformer is to translate the current of its primary winding into a proportional value of current in the secondary winding. This stepping down of current from higher primary values …
CT SATURATION: In the ideal scenario of the operation of a current transformer, the secondary current of the CT, (Is) is directly proportional to its primary current (Ip). However, in the case of saturation of the CT, the proportionality does not remain the same. Let us discuss why. …
RESTRICTED EARTH FAULT PROTECTION The most vital and important protection for a transformer is the biased differential relay protection of the transformer, which is discussed in detail in previous articles. It provides excellent protection against phase-to-phase faults and phase-to-earth faults within the differential zone of protection. It covers …
OVER FLUXING PROTECTION OF TRANSFORMER In transformer design practice the rated value of flux density is 1.7 to 1.8 Tesla. However, the saturation flux density of the CRGO steel sheet is of the order of 1.9 to 2.1 Tesla. This means the transformer core can handle a flux …
Supply of continuous electricity is the main motto of power generation, transmission and distribution. However, from our previous discussions, it is known to us that a continuous supply of power is an ideal case. Auto recloser is therefore a relay that functions to reclose the contacts of a …
STUB PROTECTION: It is basically an in-built function of a distance relay. It falls under the auxiliary part of the distance relay. It is mostly used in one-and-half-bus bar schemes. As we already know from our previous article on the bus bar scheme in one-and-a-half bus bar schemes, …
MULTIPLICATION FACTOR OF ENERGY METERS We generally use a Special energy meter for keeping the count of energy flowing through the system. The meter we use has an input connection from the current transformer’s metering core’s secondary side. With current input, we also provide the voltage input to …
ENERGY METER The meter used for the measurement of electrical energy consumed by loads in a definite time period is called an energy meter. The meter’s units are basically graded in Kwh. Energy meters are used to account for all energy transferred via the metering point for the …
OLTC OLTC or On-load tap changer is a device that is used for voltage regulation of a transformer without any interruption in the power flow to the load. Tap changing basically alters the turns ratio of the transformer thus regulating the voltage. The main feature of the On-load …
CARRIER AIDED PROTECTION The main aim of electrical power transmission is to maintain an uninterrupted power supply of electricity to all consumers. Electrical faults however cause interruption of supply. When the fault is detected by the protective relays, the fault current is interrupted by the circuit breaker. In …
The trip circuit supervision relay is the relay that monitors the healthiness of the trip circuit of a circuit breaker. It remains always vigilant and on the occurrence of any fault in the trip circuit, it raises an alarm. It is one of the most important parts of …
MASTER TRIP RELAY A master trip relay is a contact multiplier auxiliary relay used in the control and relay panel of a substation or any plant. It is a very essential part of the control and protection scheme of any substation. It offers high reliability and high contact …
The term BCU refers to the Bay Control Unit of a substation’s associated bay or feeder. The BCU or Bay control unit performs various bay operations based on pre-defined logic. It acts as an interface between the operator and the electrical switchgear present in the associated bay. It …
OTI is the oil temperature indicator of an oil-filled transformer. Since the transformer oil is also used for cooling purposes, the temperature of the oil gives out the internal thermal condition of the transformer. WTI is the winding temperature indicator of the power transformer. The windings of the …
A pressure relief valve of a transformer or PRV is a mechanical safety device used for the protection of transformers, on-load tap changers OLTC and other similar equipment which can release the excess pressure inside them because of various reasons. The Pressure relief valve of a transformer mitigates …
A protective relay works like a brain in the power system. It collects the electrical parameters from the field and computes them, senses faults, takes decisions, and gives output to the associated circuit breaker to isolate the faulted section. Protective relays can be broadly classified into three types. …
Buchholz relay is a mechanical, gas-actuated device that utilizes mercury switches to initiate alarm and trip signals on the occurrence of incipient faults inside an oil-filled transformer. It may be noted that these relays are installed on transformers above 750KVA capacity. Incipient faults are those faults that are …
Earth fault protection is a protective scheme used for the protection of an element of a power system against electrical faults involving the earth. An earth fault is an electrical fault that involves the ground. Examples are—single line-to-ground (L-G) faults and double line-to-ground (2L-G) faults. Faults that are …
A directional relay is one which is actuated by two electrical parameters namely current and voltage. The directional elements in the relay help the relay to recognize the direction of power flow based on phase angle comparison and isolate electrical faults in reverse the direction of normal power …
Overcurrent protection relays are the protective relay that operates to issue a trip command when the current value in a circuit exceeds a preset. The preset value of the current which if exceeded, makes the relay operational is known as the pickup value of the overcurrent protection relay. …
Differential protection is a relaying scheme used to protect an element of a power system from electrical faults. The differential protection scheme utilizes the vector difference of two or more similar electrical parameters and compares it to a preset value. If the preset value is exceeded it generates …
Distance protection is basically a non-unit form of protection in the power system that protects a transmission line by sensing and comparing the impedance to a set impedance value of the line. It is economical and has technical benefits. Unlike the phase, neutral overcurrent protection the main advantage …
Local breaker backup or LBB protection is a circuit breaker failure scheme that operates to protect a faulty circuit when the associated circuit breaker fails to trip, by tripping all other circuit breakers associated with the bus bar. Thus, isolating the faulty circuit. A circuit breaker functions to …
In the substation, the disconnector or Isolator does the same work as the circuit breaker do i.e., isolation of the circuit from the power supply. But the difference is that initially automatic circuit isolation/ tripping is achieved by a circuit breaker or CB due to the arc quenching …
A lightning arrester is a protective device which conducts or diverts the harmful high voltage surges on the power system safely to the ground. It is the frontline warrior used for the protection of equipment against the travelling waves and overvoltages in the overhead transmission line. Though the …
Potential Transformer: A potential Transformer or voltage transformer is a type of instrument transformer that is used to step down the voltage from a higher level to an optimal level where it can be measured safely. It has higher turns in the primary winding and a smaller number …
A Current transformer is a type of instrument transformer that is used to step down the current of the primary side to a minimal value on the secondary side for ease of metering using standard ammeters and for protection purposes. As nowadays most relays are numeric and digital …
Transformer oil or mineral oil is used extensively in the transformer to provide electrical insulation between the core, windings, and the body of the transformer. The live part of the transformer, core, and winding are submerged in transformer oil that provides electrical insulation to the main tank. Transformer …
A Circuit breaker is a device that can operate on command to make or break an electrical circuit in a fraction of a second. Breaking a circuit on detection of an electrical fault is very essential otherwise fault current propagation for enhanced time can potentially damage the electrical …
