siva prakash B

Impact of low voltage on meter performance

7

The Difference between a Lightning Arrester and a Surge Protector（SPD） In electrical systems, both lightning arresters and surge protectors play a role in protecting equipment from overvoltage, but there are some important differences between them. 🧡 The working principle 1. Lightning arrester - The arrester mainly uses nonlinear resistance elements (such as zinc oxide) to quickly switch on at high voltage, limit the overvoltage to a certain level, and then cut off the power frequency continuous current, thereby protecting the electrical equipment. - When overvoltage such as lightning acts on the arrester, the resistance value of the zinc oxide resistor decreases rapidly, forming a low impedance path, and the overvoltage current is introduced to the ground. 2. Surge Protector (SPD) - Surge protectors are usually composed of components such as varistors and gas discharge tubes. When there is a surge, the resistance value of these components changes rapidly, which limits the rise in voltage and protects the device. - Varistor has a high resistance value at normal operating voltage, and when the voltage exceeds its threshold, the resistance value drops sharply, diverting the surge current to the ground. 🌺 Application scenarios 1. Lightning arrester - Mainly used to protect high-voltage equipment in the power system, such as transformers, circuit breakers, transformers, etc. More installed on a system to prevent direct intrusion of lightning waves; - Generally installed in substations, power plants and other places 2. Surge protector - Widely used in low-voltage electrical systems, such as building power distribution systems, electronic equipment, communication equipment, etc. Installed on the secondary system, it is a supplementary measure when the lightning arrester eliminates the direct intrusion of the lightning wave, or the lightning arrester does not eliminate the lightning wave. - It can be installed in the power distribution box, power distribution cabinet, and front end of the equipment. 🍁 Performance parameters 1. Lightning arrester - Nominal discharge current: usually tens of kiloamps (kA) to hundreds of kiloamps, such as 80kA, 100kA and so on. Residual voltage: relatively high, generally at several thousand volts (kV) level, such as 3kV, 5kV, etc. 2. Surge protector Nominal discharge current: generally below tens of thousands of amps, common 20kA, 40kA and so on. - Residual pressure: low, usually between a few hundred volts to more than one thousand volts, such as 800V, 1200V, etc. 🌹 Response time 1. Lightning arrester - The response time is relatively long, generally in the microsecond (μs) level, such as 50μs, 100μs, etc. 2. Surge protector - The response time is short, usually in the nanosecond (ns) level, such as 25ns, 50ns, etc. whatsapp:008615257206533

17

For learners having interest in Transformer and Reactor Beginner to advance learning Transformers and Reactor Learning Series-6/n contd…. Shunt Reactor and Neutral Grounding Reactor (NGR): Some important Point to understand  Shunt reactors will be connected to the transmission system for reactive compensation and shall be capable of controlling the over voltages occurring in the system. The neutral grounding reactor is required for grounding of the neutral point of shunt reactor (for line reactor only) to limit the secondary arc current and the recovery voltage to a minimum value. 765 kV shunt reactors shall be designed for switching surge overvoltage of 1.9 p.u. and temporary over voltage of the order of 1.4 p.u. for about 15 cycles followed by power frequency overvoltage upto 830 kVrms for about five minutes. The reactor shall withstand the stress due to above transient conditions which may cause additional current flow as a result of changed saturation characteristics/slope beyond 1.25 p.u. voltage. 420 kV and below shunt reactors shall be designed for switching surge overvoltage of 2.5 p.u. and temporary overvoltage of the order of 2.3 p.u. for few cycles followed by power frequency overvoltage upto 1.5 p.u. The reactor must withstand the stress due to above transient conditions which may cause additional current flow as a result of changed saturation characteristics/ slope beyond 1.5 p.u.  The thermal and cooling system shall be designed for maximum continuous operating voltage Um (where Um= 800/√3 kV for 765/√3 kV reactor; 420 kV for 420 kV reactor & 245 kV for 245 kV reactor). In addition, the reactors shall be designed to withstand the following over-voltages repeatedly without risk of failure (w.r.t. Hotspot temperature of 140 oC & core saturation): 1.05 Um Continuous (for 765 kV & 420 kV reactor) 1.10 Um Continuous (for 245 kV reactor) 1.50 Um for 5 seconds 1.25 Um for 1 minute The winding hot spots shall be calculated considering the maximum localized losses, insulation thickness at the maximum loss and the oil flow patterns in the winding. The oil temperature rise in the windings shall be used to determine hot spots rather than the bulk top oil temperature. The hot spot for all leads shall be calculated and it shall not exceed the calculated hot spot of the windings. Tank hotspot temperature under over voltage condition specified above shall not exceed 110 deg C considering maximum ambient temperature as 50 deg C. Also, the most onerous temperature of any part of the core and its supporting structure in contact with insulation or non-metal material shall not exceed the safe operating temperature of that material. Adequate temperature margins shall be provided to maintain long life expectancy of these materials. Happy Learning

17

2 Comments

This article delves into the realm of pole discrepancy in high voltage circuit breakers, shedding light on its mechanisms, applications, and the pivotal role it plays in enhancing system reliability. From understanding the choice between gang (three-pole) and independent (single-pole) operated circuit breakers to dissecting the challenges posed by conventional technologies, we embark on a journey to explore the intricacies of pole discrepancy and its implications in various network topologies. https://lnkd.in/dBbXT554

40

GE T&D is the listed entity of GE’s Grid Solutions business in India. It has been in the power transmission and distribution business for more than 100 years and provides a versatile range of solutions for connecting and evacuating power from generation sources onto the grid. #GETD #PowerTransmission #PowerDistribution #GridSolutions #SustainableEnergy #Electricity #RenewableEnergy #EnergySolutions #IndiaEnergy #GreenPower #Innovation #Technology #FutureOfEnergy #dsij #dalalstreetjournal #dalalstreetupdate

1

Some of key learning noted in April Month POWER PROJECTS IPSA Short circuit studies Q&A weekly classes are 1.    As per IEC 60909, All line capacitances and shunt admittances of non-rotating loads except those of zero sequence system are neglected. If included, short circuit current will be slightly reduced because shunt capacitance holds some voltage (V) at the faulty point and hence E-V < E -0 where E is the Grid voltage. 2.    Capacitor bank consumes not only reactive power but also real power (i.e. Losses) – Losses in the range up to 2%. 3.    While performing motor starting study, consider only the minimum short circuit current at grid with all other current contributing sources neglected by modelling remaining loads as lumped load with very minimum possible short circuit contribution from it. 4.  Always run short circuit study with nominal tap, ETAP will automatically consider percentage impedance at nominal tap even though tap is in other than nominal position. (Impedance correction factor KT will take care of required compensation) 5.  For HV star ungrounded LV star Grounded transformer (Yyn), although simulation results say there is no earth fault current at LV side but practically there will be SLG fault current due to transformer construction (5 limb) or due to presence of buried delta winding. 6.    In LV System, DC component decays very fast (low X/R) hence DC interrupting capability not required. 7.    Outgoing feeders not necessarily to be rated for maximum short circuit current if Incomer circuit breakers are current limiting type circuit breakers in LV system. Explained well by Mr. Selvakumar S

34

6 Comments

⚡ Finding the #LightningRiskAssessment (LRA) Calculator in ETAP 2024 (vs. ETAP 22.5) 🌩️   In this final video of the series, Raghu VeeraRaghavan guides you through locating the Lightning Risk Assessment (LRA) calculator in ETAP 2024’s PowerRibbon compared to the classic ETAP 22.5 interface. This feature is a game-changer for users who need quick and reliable lightning risk assessments.   Dive into the enhanced layout and see how ETAP 2024 makes essential tools even easier to access and use!   #ETAPSoftware #LightningRiskAssessment #RibbonView #ElectricalSafety #EngineeringTools

59

Distance Relay - REL 670 Simply explained about how we export Parameters from relay and how we create default setting file in Omicron using PTL . And how we import relay Parameters in xrio file .

92

5 Comments

Rated voltage in India ….. Today , the need of electricity is without any question. With smart meter we can expect improvement in power quality as monitoring will start !! Voltage quality is one of prime parameter !! First aim should be to keep voltage near to RATED VOLTAGE …. Vr Next important question what Rated voltage in India .. My understanding it is 230V. ( in Delhi DERC also says so). But then why BIS standard define rated voltage differently .. for eg Single phase energy meter … 240V Distribution transformer .. 11Kv / 433V ie Vpn approx 255V. Why confusion of different value ?? If we see American or Japanese’s standard they talk of one rated voltage 110V.. in all documents. Let us review basic question :: Who defines Rated voltage ( in India) ?? What value is defined . Can / should standardisation agency change it ?? What is the need .. Can any other agency like regulator etc has authority to change it ?? I feel let us stick one value of 230 V .. of course if valid reasons would like to learn ..

112

42 Comments

🌟 Selecting Capacitor Bank Steps in an APFC Panel with Calculations! 🌟 When designing an Automatic Power Factor Correction (APFC) panel, selecting the right number of capacitor steps is crucial for efficient operation. Capacitor steps allow dynamic correction of power factor based on the varying load requirements. Today, we’ll explore the step-by-step process of determining capacitor bank steps based on the load, with practical calculations to guide you. --- 🔍 Why are Capacitor Steps Necessary? Industries operate under fluctuating loads, and their power factor varies accordingly. To maintain a consistent power factor (usually above 0.95), APFC panels are equipped with capacitors divided into multiple steps. These steps help activate or deactivate capacitors as the load demands, ensuring optimized performance and avoiding penalties. Now, let’s dive into the calculation process! --- 🧮 Steps to Determine Capacitor Bank Steps (with Calculations): Step 1: Understand the Total Reactive Power (kVAR) Required The first step is to calculate the reactive power required for power factor improvement. Use the formula: kVAR = kW × (tanΦ1 - tanΦ2) Where: Φ1 = Cos⁻¹ (initial power factor) Φ2 = Cos⁻¹ (desired power factor) For example: Initial power factor = 0.80 Desired power factor = 0.98 Load = 500 kW Φ1 = Cos⁻¹ (0.80) = 36.87° Φ2 = Cos⁻¹ (0.98) = 11.47° kVAR = 500 × (tan 36.87° - tan 11.47°) kVAR = 500 × (0.75 - 0.20) kVAR = 500 × 0.55 kVAR = 275 kVAR So, a 275 kVAR capacitor bank is required. --- Step 2: Divide the kVAR into Suitable Steps Divide the total kVAR into steps for flexibility and efficient load handling. A general rule is to use a combination of binary or equal steps. Example 1: Binary Steps Approach If the total kVAR = 275 kVAR, divide into binary steps: Step 1: 25 kVAR Step 2: 50 kVAR Step 3: 50 kVAR Step 4: 100 kVAR Step 5: 50 kVAR Example 2: Equal Steps Approach Divide the total kVAR equally: 5 steps of 55 kVAR each. The choice depends on your system’s load pattern. Binary steps offer finer control, while equal steps are easier to implement. --- Step 3: Verify Step Configuration Ensure that the step combination can handle both the minimum load correction and the maximum load requirement without overcorrection or undercorrection. For example, in our binary configuration: Minimum step = 25 kVAR (covers light loads) Maximum combined steps = 275 kVAR (covers peak loads) --- Disclaimer : "© 2024 Sarfraz. This content is my intellectual property and is protected under copyright laws. I encourage you to share and learn from it, but copying, or reproducing any part of this content without my prior permission is strictly prohibited. Let’s grow together by respecting original ideas!" #APFCPanels #ElectricalEngineering #PowerFactorCorrection #CapacitorBankDesign #ElectricalCalculations #EngineeringInsights #PowerFactor #EnergyEfficiency #IndustrialAutomation

276

16 Comments

A bypass capacitor is used to minimize high frequency noise into the supply pin of the DRV device. TI recommends placing capacitors as close as possible to the power input pins of the device and ground pins. If the trace lengths between the bypass capacitor and the device are not minimized, they can be inductive at the high frequencies that the bypass capacitor is meant to filter. The added impedance from trace inductance can cause ringing in the voltage or current at the supply pin which contributes to EMI and affects the performance of digital or analog circuits. A best practice is to place the capacitor with the lesser value as close as possible to the device to minimize the influence of the inductance of the trace. Connect larger-value capacitors after the smaller ones because as the value of the capacitor increases the inductance becomes more negligible.

47

2 Comments

You have a 26 MVA, 132/11 kV transformer with a vector group Dyn11. *Key Characteristics:* 1. Rating: 26 MVA (Megavolt-amperes) 2. Primary Voltage: 132 kV 3. Secondary Voltage: 11 kV 4. Vector Group: Dyn11 (Dynamically connected, 11 o'clock configuration) 5. Winding Configuration: 3-phase, 2-winding transformer *Dyn11 Vector Group:* The Dyn11 vector group indicates: 1. Primary (HV) side: Delta-connected (Δ) 2. Secondary (LV) side: Star-connected (Y) 3. Phase shift: 30° (between HV and LV sides) *Fault Analysis (assuming one phase missing on HV side):* If one phase is missing on the 132 kV (HV) side: 1. HV side: Delta-connected, so the missing phase will not directly affect the LV side. 2. LV side (11 kV): Star-connected, which will experience unbalanced voltages due to the missing phase on the HV side. *Effects on LV side:* 1. Voltage unbalance: ±10-15% (approximate) 2. Current circulation: Increased copper losses, potentially leading to overheating 3. Neutral shift: Possible voltage unbalance and increased stress on insulation 4. Reduced power output: Transformer capacity reduced due to unbalanced operation *Protection Considerations:* 1. Overcurrent protection: May not detect unbalanced conditions 2. Neutral overvoltage protection: Recommended to prevent insulation damage 3. Differential protection: Essential for detecting internal faults *Operation and Maintenance:* 1. Monitor voltage and current unbalance 2. Check transformer temperature and oil quality regularly 3. Perform routine maintenance (e.g., inspections, testing) To mitigate the effects of a missing phase, consider: 1. Reconnecting the missing phase (if possible) 2. Adding a compensating device (e.g., zigzag transformer) 3. Derating the transformer to prevent overheating Please consult the transformer's manufacturer documentation and/or seek expert advice for specific guidance tailored to your situation.

28

1 Comment

Variable Frequency Drives! Presently, no building design is complete without the utilization of VFD. It is the device which is used to vary the speed of motors. The ultimate goal is to save energy. First of all, it is not the frequency only which is varied in VFD but corresponding voltage is also changed to ensure flux in the motor remains uniform throughout the variation in the frequency. Second, the knowledge of affinity laws is fundamental for correct application of VFD. Flow will be directly proportional to the change in speed, head will be Squared of change in speed and energy saving will be cube of speed change! The VFD needs to be applied when load is variable. The best application for VFD is the HVAC load which varies with time of day and outside temperature. It is interesting to note that throttling will help reduce flow but the motor will be running at full speed and capacity consuming brake horsepower energy. The only change will be the shift in optimum utilization point at pump curve to the left closer to the shutoff pressure. Below example will help clarify the energy saving compared to change in speed! #energysaving #sustainability #vfdcontrols #variableflow #VFD

2

1 Comment

For learners having interest in Transformer and Reactor from 66 kv and above Transformers and Reactor Learning Series- The phenomenal growth of Indian Power transmission system has resulted in the formation of One Nation One Grid, one of the largest single synchronous Grids in the world. The transmission system establishes the vital link between the generating source and the distribution system connected to the ultimate consumer. The transformer and reactor are vital and expensive assets in a power system. The increase in demand for energy will require enhancement in transformation capacity as well as reactive compensation requirement. Reliability and availability of such important assets plays an important role in the smooth operation of a power system. Generally, due to poor quality of raw material, workmanship, and manufacturing techniques or due to normal and abnormal stresses of the system during the operation (like frequent system faults, over loading, environmental effect, unexpected continuous operating voltage and over voltage stresses), and poor maintenance practice, transformers/reactors fail much before their expected life span (expected life span of about 35 years). The failure of such vital equipment can have significant economic impact due to high cost, long lead time in procurement, manufacturing and installation. Long repair time is a matter of concern in many cases of failure of transformer/reactor. Restoration of transformer/reactor takes about 3 to 6 months after major repair at manufacturer’s works depending on the type of repair and procurement of a new one requires 6-10 months depending on the voltage class of transformer/reactor. Suggestion: Emphasis needs to be laid on 1- Improved design, 2-Quality control during manufacturing, 3-Use of right components/accessories, 4-Maintenance and safety during operation of Transformer and Reactor Feel free to add your valuable input….. to make this post more useful.

27

For learners having interest in Transformer and Reactor from 66 kv and above Beginner to advance learning Transformers and Reactor Learning Series-4/n contd…. Let’s us now learn about “TECHNICAL SPECIFICATIONS FOR TRANSFORMERS AND REACTORS” contd.. The transformer shall be free from any Electrostatic Charging Tendency (ECT) under all operating conditions and maximum oil velocity shall be such that it does not lead to static discharges inside the transformer while all coolers are in operation. The transformers shall be capable of operating continuously at the rated MVA without danger, at any tapping with voltage variation of +-10% corresponding to the voltage of that tapping. The transformers shall be capable of being over loaded in accordance with IEC 60076-7. There shall be no limitation imposed by bushings, tap changers etc. or any other associated equipment. The hotspot temperature in any location of the tank shall not exceed 110 degree Celsius at rated MVA. This shall be measured during temperature rise test at manufacturer’s works. The maximum flux density in any part of the core and yoke at the rated MVA, voltage and frequency shall be such that under 10 % continuous over-voltage condition it does not exceed 1.9 Tesla at all tap positions. The transformer and all its accessories including bushing/built in CTs etc. shall be designed to withstand the thermal and mechanical effects of any external short circuit to earth and of short circuits at the terminals of any winding without damage. The transformer shall be designed to withstand the thermal stress due to short circuit for a duration of 2 seconds and the same shall be verified during design review. However, generator transformer and associated auxiliary transformer shall be designed to withstand the thermal stress due to short circuit for a duration of 3 seconds. The following short circuit level shall be considered for the HV & IV System to which the transformers will be connected: 765kV system- 63 kA for 1 sec (sym, rms, 3 phase fault) 400kV system- 63 kA for 1 sec (sym, rms, 3 phase fault) 220kV system - 50 kA for 1 sec (sym, rms, 3 phase fault) 132kV system - 40 kA for 1 sec (sym, rms, 3 phase fault) 66kV system- 31.5 kA for 1 sec (sym, rms, 3 phase fault) However, for transformer design purpose, the through fault current shall be considered limited by the transformer self-impedance only (i.e. Zs = 0). Happy Learning……. I hope at the end you all will have a fair idea of Transformers and reactor…

10

Transformer !Transformer !Transformer ! How can we make transformer tanks stronger to handle different types of pressure and stress better? Making transformer tanks stronger to handle different types of pressure and stress involves several engineering considerations and modifications. Here are some strategies to enhance transformer tank strength: 1. **Material Selection**: Use high-strength materials such as stainless steel or reinforced steel for constructing transformer tanks. These materials offer better resistance to pressure and stress compared to traditional mild steel. 2. **Thicker Walls**: Increase the thickness of the tank walls to improve its structural integrity and ability to withstand external pressure and stress. 3. **Ribbing and Reinforcements**: Introduce internal ribbing or external reinforcements to distribute stress more evenly throughout the tank structure, reducing the likelihood of weak points or failure under pressure. 4. **Weld Quality**: Ensure high-quality welding techniques are employed during tank construction to minimize the risk of weld defects or weak joints that could compromise strength. 5. **Seamless Construction**: Opt for seamless construction techniques where possible to eliminate potential weak points along seams or joints. 6. **Corrosion Resistance**: Implement coatings or materials that offer corrosion resistance to protect the tank from degradation over time, which can weaken its structural integrity. 7. **Pressure Relief Devices**: Install pressure relief devices such as valves or rupture disks to alleviate excess pressure buildup within the tank, thereby reducing the risk of catastrophic failure. 8. **Structural Analysis**: Conduct thorough structural analysis using advanced simulation tools to identify potential stress points and optimize the tank design accordingly. 9. **Testing and Certification**: Subject transformer tanks to rigorous testing protocols to verify their strength and performance under various pressure and stress scenarios. Ensure compliance with relevant industry standards and certifications. 10. **Innovative Designs**: Explore innovative tank designs or configurations that offer improved strength-to-weight ratios or novel stress distribution mechanisms. By implementing these strategies, transformer tanks can be made stronger and better equipped to handle different types of pressure and stress, thereby enhancing their reliability and longevity in service. #Transformers, #distributiontransformer , #PowerTransformer, #DesignTrainings, #transformertank

22

1 Comment