Characteristics of a good dielectric material (engineering insulation) Which combination best describes the desired properties of an engineering dielectric intended for capacitors, cables, and high-voltage insulation?

Introduction / Context:
Dielectrics are used wherever electric fields must be sustained with minimal loss and without breakdown — from power capacitors and cables to printed circuit boards and sensor dielectrics. A “good” dielectric should meet multiple criteria simultaneously, not just a high permittivity value. This question consolidates the key performance attributes designers look for in practice.

Given Data / Assumptions:

• Operating in AC or DC fields with acceptable temperature rise.
• Materials compared at similar thickness and environmental conditions.
• Focus on bulk properties important for reliability and efficiency.

Concept / Approach:

(a) Low dielectric loss (low loss tangent tan δ) minimizes I^2R-like heating and improves efficiency and stability; it is crucial for RF, high-frequency, and precision applications. (b) Good thermal conductivity helps to remove whatever heat is generated, preventing thermal runaway and extending lifetime; modern dielectrics may be filled with ceramic particles to enhance heat conduction. (c) High intrinsic dielectric strength allows the material to withstand high electric fields before breakdown, enabling compact, high-voltage designs. The best dielectrics balance these traits to meet mechanical, chemical, and cost constraints as well.

Step-by-Step Solution:

Verification / Alternative check:

Standards such as IEC and ASTM tests on tan δ, thermal conductivity, and breakdown strength collectively determine suitability in capacitors, cables, and HV bushings.

Why Other Options Are Wrong:

Picking only one or two properties ignores the multidisciplinary constraints. Real insulation systems fail if any of these is inadequate.

Common Pitfalls:

Overemphasizing dielectric constant εr while neglecting thermal and loss performance, or vice versa.

Final Answer:

All of the above