Comparison Between Uniform Field and Non-uniform Field

Sr.
No.

Point
of comparison

Uniform
Field

Non-uniform
Field

1.

Definition

When electric field intensity is same everywhere in a gap and both
electrode surfaces then it is known as uniform field.

When electric field intensity is different everywhere in the gap and
also on electrode surfaces it is known as uniform field.

2.

Example

Sphere – sphere

Rod – rod

Plate – plate

S/D = 0.6

Point. – electrode,

Sphere. – rod,

Flat. – sphere, etc.

S/D  reaching towards 1

3

Breakdown phenomenon

When field is uniform ionization occurs everywhere in the gap due to
uniform field intensity and breakdown is observed with spark.

In non-uniform field ionization occurs near electrode surface having
high field intensity and breakdown occurs with partial discharge and corona.

4.

Corona

There is no corona discharge.

Corona discharge occurs.

5.

Theory

Townsend’s theory is applied for studying.

Streamers theory is used for explaining Breakdown.

6.

Nature of breakdown

Breakdown is easy to understand.

Difficult to understand.

7.

Development of theory

Breakdown process is developed satisfactorily.

The theory is still under development.

8.

Breakdown voltage (breakdown voltage)

Breakdown voltage is high.

Breakdown voltage is low.

9.

Effect of polarity

Breakdown is not affected due to polarity of electrodes.

Breakdown is affected due to polarity of electrodes.

10.

Example

Plate-plate, sphere-sphere for S/D < 0.6

Rod-plate, Needle-plate, sphere-plate electrodes negative.

11.

Current

With increase in applied voltage, current through gap increases
steadily.

Increase in applied voltage, current through gap increases steadily.