Question

The breakdown strength of air at STP is 21kV (rms) /cm.The breakdown strength of air at 30°C and 72cm of Hg is approximately

a. 21.25kV(rms) /cm
b. 20.20kv(rms) /cm
C. 23kV(rms) /cm
d. 19.6kV(rms) /cm​

Answer 1

Answer:

a 21.25KV(RMS)/cm

Explanation:

air at 30°C and 72cm of Hg is approximately

Answer 2

The breakdown strength of air at 30 degree is 21.25 kV(rms)/cm

Answer - option A

Explanation-

Many electrical power systems or devices use air as an insulating medium. it is given that at standard temperature and pressure the air has a breakdown strength of 21kV(rms)/cm.

The high breakdown current is produced in in air for insulation medium because of the ionization that takes place in the medium and movement of positive and negative ions to the opposite sides of the charges.

In the case of air when it is taken as an insulating medium then it is studied that at 30 degrees and  72 Hg  the air will have a breakdown strength of 21.25 kV(rms)/cm.This breakdown strength may vary depending on the configuration of electrode temperature pressure and Initial conducting particles.

There are theories explaining the effect of these factors on breakdown strength and by studying the table or formula that is provided by these two theories will have above given breakdown strength.  

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