MEASUREMENT_OF_DI_ELECTRIC_STRENGTH_INSULATOR-1.pptx

Measurements of Dielectric Strength and Insulators

1. MEASUREMENT OF DI ELECTRIC STRENGTH INSULATOR HIGH VOLTAGE SURGES

2. Introduction

3. WHAT IS DI ELECTRIC?

4. What is DI Electric Strength?

5. Dielectric Breakdown Dielectric strength refers to the voltage required to cause dielectric breakdown, which results in the passage of current through an insulating material. This breakdown may cause the material to no longer act as an insulator due to potential changes in its molecular structure. For instance, the dielectric strength of air is 3 kV/mm .

6. Di Electric Strength of various insulators Material Dielectric strength (kV/inch) Variation Vacuum 20 kV/inch "The values can vary depending on the experimental conditions." Air 20 to 75 kV/inch "The value may change depending on pressure, humidity, and other factors." Porcelain 40 to 200 kV/inch The dielectric strength of porcelain varies depending on its composition and manufacturing quality. Paraffin Wax 200 to 300 kV/inch commonly used in electrical insulation applications. Transformer Oil 400 kV/inch The high dielectric strength of this material makes it suitable for cooling and insulating transformers. Bakelite 300 to 550 kV/inch "Bakelite is a commonly used insulating material known for its high dielectric strength." Rubber 450 to 700 kV/inch "The value may vary depending on the type of rubber and additives utilized." Shellac 900 kV/inch Shellac is a resin that is used for electrical insulation due to its high dielectric strength. Paper 1250 kV/inch Specially treated insulating paper can meet these requirements. Teflon 1500 kV/inch Teflon possesses excellent insulating properties. Glass 2000 to 3000 kV/inch The dielectric strength of glass may vary depending on its composition and quality. Mica 5000 kV/inch "Mica is known for its exceptionally high dielectric strength."

7. Measurement of Dielectric Strength

8. Measurement of Dielectric Strength Measuring the dielectric strength of an insulating material helps determine its maximum voltage tolerance without damage. This process requires special equipment tailored to the specific characteristics of the material being tested. Here’s a summary of the methods and tools used for testing different types of insulating materials:

9. Method of Measurement 1. Place the insulating material between the electrodes. 2. Ensure that the voltmeter shows zero reading. 3. Switch on the main supply. 4. Switch on H.T. supply. 5. Raise the voltage gradually. 6. Use the memory switch to note down the reading of the voltmeter in the observation table when a breakdown occurs. 7. Repeat the above procedure for each specimen of insulating material. 8. Derive conclusion.

10. Measurement of Di electric Strength of Solid

11. Instrument used for the measurement of Di electric Strength of Solid

12. Measurement of Di electric Strength of Liquid

13. Instrument used for the measurement of Di electric Strength of Liquid Insulator Apparatus: High Voltage Oil Testing kit Transformer Oil

14. Measurement of Di electric Strength of Gaseous Insulators

15. Instrument used for the measurement of Di electric Strength of Gaseous Insulator Sphere Gap Transformer

16. Problem to find di electric strength of a Solid Insulator QUESTION: A dielectric material has a dielectric strength of 50 kV/mm. A sample of this material is placed between two parallel plates which are 0.2 mm apart. Calculate the maximum voltage that can be applied across the plates without causing dielectric breakdown. Solution Steps:1. Understand the given data: Dielectric strength (Ed): 50 kV/mm Distance between plates (d): 0.2 mm The formula for dielectric strength: The dielectric strength is given by the maximum electric field E that the material can withstand: Ed=Vmax/d where V max is the maximum voltage applied across the material and d is the distance between the plates. Rearrange the formula to solve for V max : Vmax =Ed ×d Substitute the given values into the formula: Vmax =50 kV/mm×0.2 mm Calculate the maximum voltage: Vmax =50 × 0.2=10kV Conclusion: The maximum voltage that can be applied across the plates without causing dielectric breakdown is 10 kV.

17. Question: A container with a liquid dielectric material has a thickness (distance between electrodes) of 3 mm. The material breaks down when a voltage of 45 kV is applied. Calculate the dielectric strength of the liquid. Given: Thickness of the liquid, d = 3mm = 3 × 10^-3m Breakdown voltage, V = 45kV = 45×10^3V Formula: E=V/d Calculation: E = (45×10^3V)/(3×10^-3m) E = (45×10^3)/(3×10^-3) E = 15×10^6 V/m E = 15 MV/m Answer: The dielectric strength of the liquid is 15 MV/m. Problem to find di electric strength of a Liquid Insulator

18. Problem to find di electric strength of a Gaseous Insulator Question : You are testing the dielectric strength of air used as an insulating material between two spherical electrodes. The test involves applying a voltage across the gap between the spheres until breakdown occurs. Given Data: Breakdown Voltage ( Vb )= 1000 volts Gap Between Spheres (d): 5 cm Solution: Dielectric Strength = Breakdown Voltage / Gap Between Spheres Dielectric Strength = 1000 V / 5 cm Dielectric Strength = 200 V/cm

19. 1 2 3 4 Significance of di electric strength

20. Applications of Dielectric Strength: Where Precision is Key 1) Electrical Insulation: Power Cables: Ensure efficient electricity flow while reducing risks to people and property. Transformers and Capacitors: Enable reliable energy storage and management. 2) High Voltage Equipment: Switchgear and Circuit Breakers: Essential for safely interrupting high currents, and protecting systems from overloads or faults. Power Distribution: Prevents electrical breakdown and ensures a stable power supply. 3) Electronics: Printed Circuit Boards (PCBs): Maintain insulation between conductive layers, preventing unintended electrical connections. Semiconductor Manufacturing: Insulate and protect delicate components during production. 4) Thermistors: Temperature Sensing: Use dielectric materials to detect temperature changes, influencing sensitivity and reliability in electronic devices, automotive systems, and industrial processes.

21. Challenges and Innovations Continual research in materials science seeks to improve dielectric properties, aiming to create more efficient and compact electrical systems. Advances in nanotechnology may result in materials with enhanced dielectric strength.

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