Intrinsic and Thermal Breakdown - High Voltage Engineering

TL;DR

Understanding intrinsic and thermal breakdown mechanisms in dielectrics under different conditions.

Transcript

hello friends let us discuss next topic that is intrinsic and thermal breakdown these two topics are different like intrinsic breakdown and thermal breakdown are the two different topics which we had to study in this lecture so what we have in intrinsic breakdown that is going to be studied first so in intrinsic breakdown when voltages are applied ... Read More

Key Insights

• 🥶 Intrinsic breakdown increases dielectric strength through the presence of free electrons and structural imperfections.
• 🎏 Two proposed mechanisms for intrinsic breakdown are electronic breakdown and streamer breakdown.
• 🥵 Thermal breakdown results from heat generated by conduction current, setting an upper limit on breakdown voltage with increasing insulation thickness.
• 🥵 The frequency of the electric field directly impacts the heat generated in dielectrics, affecting the severity of thermal breakdown.
• ✋ In high-frequency conditions, thermal breakdown is more serious due to rapid temperature increase.

Questions & Answers

Q: What is intrinsic breakdown and how does it affect dielectric strength?

Intrinsic breakdown is when solid dielectric specimens compact under current heating, leading to increased dielectric strength due to the presence of free electrons allowing for greater conduction.

Q: What are the proposed mechanisms for intrinsic breakdown?

The proposed mechanisms for intrinsic breakdown include electronic breakdown, where collisions lead to electron conduction, and streamer breakdown, which is similar to gas breakdown involving cumulative ionization.

Q: How does thermal breakdown occur in dielectrics?

Thermal breakdown occurs when heat generated by conduction current in dielectrics causes a rise in temperature, potentially exceeding the breakdown voltage if the heat generated surpasses the heat dissipation.

Q: Why is thermal breakdown important in high voltage power apparatus?

Insulation failures often occur in high voltage power apparatus due to thermal breakdown, setting an upper limit on breakdown voltage when increasing insulation thickness.

Summary & Key Takeaways

• Intrinsic breakdown occurs due to compacting of solid dielectric specimens under current heating, increasing dielectric strength.

• Electron avalanche and streamer breakdowns are proposed mechanisms for intrinsic breakdown.

• Thermal breakdown results from heat generated by conduction current in dielectrics, affecting breakdown voltage.