Docsity
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Docsity AI
Docsity AI
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search for your university

Find the specific documents for your university's exams

Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

Tutorials and test paper about break down streamer, Exercises of Volcanology

University of KwaZulu-NatalVolcanology

High voltage refers to the electrical potential difference or electromotive force (EMF) between two points in an electrical circuit or system that is significantly higher than the standard voltage levels used in most everyday applications. While the exact threshold for what is considered "high voltage" can vary depending on context and safety standards, it typically starts at a voltage level of around 1,000 volts (1 kilovolt, kV) or higher. High voltage is used in various industrial, scientific, and power transmission applications, and it has several important characteristics and considerations:

Typology: Exercises

2022/2023

Uploaded on 09/06/2023

phelokazi-mwetu
phelokazi-mwetu 🇿🇦

3 documents

1 / 3

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Electrical, Electronic and
Computer Engineering
ENEL4HA - High Voltage 1
Tutorial 1 - Conduction and Breakdown in Gases
Theoretical Questions
•Define Townsend’s first and second ionisation coefficients.
•Define photoionisation and list the reactions in your answer.
•Explain why breakdown is dependent on pressure? Is the breakdown voltage higher or lower
at high altitude?
•Describe Paschen’s law.
•Describe anode and cathode directed streamers. What is the difference?
•Describe vacuum breakdown.
•What is the leader mechanism and how does it relate to the lightning strike?
•What is corona?
•Explain time lags in breakdown
Question 1
A voltage of 12 kV is applied between two parallel plates that are separated by a gap of 5 mm,
a current of 850 µA flows in the gap. If the gap is reduced to 2 mm, 80 muA flows. Determine
Townsend’s first ionisation coefficient.
Question 2
Two metallic spheres of radius 150 mm are separated by an air gap of 25 mm.
•Estimate the breakdown voltage
•Determine the breakdown voltage more accurately using the streamer breakdown criterion?
Explain the difference in accuracy.
Question 3
A metallic sphere of radius 225 mm is situated above an infiinite metallic sheet and is separated
by an air gap of 10mm.
•Estimate the breakdown voltage
•Determine the breakdown voltage more accurately using the streamer breakdown criterion?
Explain the difference in accuracy.
1
pf3

Partial preview of the text

Download Tutorials and test paper about break down streamer and more Exercises Volcanology in PDF only on Docsity!

Electrical, Electronic and

Computer Engineering

ENEL4HA - High Voltage 1

Tutorial 1 - Conduction and Breakdown in Gases

Theoretical Questions

  • Define Townsend’s first and second ionisation coefficients.
  • Define photoionisation and list the reactions in your answer.
  • Explain why breakdown is dependent on pressure? Is the breakdown voltage higher or lower at high altitude?
  • Describe Paschen’s law.
  • Describe anode and cathode directed streamers. What is the difference?
  • Describe vacuum breakdown.
  • What is the leader mechanism and how does it relate to the lightning strike?
  • What is corona?
  • Explain time lags in breakdown

Question 1

A voltage of 12 kV is applied between two parallel plates that are separated by a gap of 5 mm, a current of 850 μA flows in the gap. If the gap is reduced to 2 mm, 80 muA flows. Determine Townsend’s first ionisation coefficient.

Question 2

Two metallic spheres of radius 150 mm are separated by an air gap of 25 mm.

  • Estimate the breakdown voltage
  • Determine the breakdown voltage more accurately using the streamer breakdown criterion? Explain the difference in accuracy.

Question 3

A metallic sphere of radius 225 mm is situated above an infiinite metallic sheet and is separated by an air gap of 10mm.

  • Estimate the breakdown voltage
  • Determine the breakdown voltage more accurately using the streamer breakdown criterion? Explain the difference in accuracy.

Question 4

A coaxial busbar with an inner conductor with external radius of 15 mm and outer conductor with internal radius of 75 mm. The system is filled with SF6 at 3 bar.

  • Estimate the breakdown voltage.
  • Determine the breakdown voltage more accurately using the streamer breakdown criterion? Explain the difference in accuracy.