Answer / roysayan01

well let me answer my own question-

I'll let you know,measuring Corona loss is no child's
play.Even if you are well equipped in the field of power
transmission, errors would creep in.

The expression for corona loss is given by

Peek's equation

Pcl = (244/q)*(f+25)*(Sqrt(r/D))*(Vph -Vd0)^2 * 10^ -5
Kw/Kw/phase
You think that's complicated? There is more to come.

In the above expression r is the radius of the wire in
meters and D is the effective distance between the wires in
meters,f is the frequency of transmission voltage,Vph is the
voltage to neutral or the phase voltage and Vdo is the
Disruptive critical voltage.

q = Air density factor which is given by expression
((273)/760)* p/(273+t)

All the calculations for q are done by converting
temperature into Kelvin scale
273 K in the Standard temperature and 760 mm of mercury is
the standard pressure and they are taken into consideration
in the above expression.
p is the atmospheric pressure when measurement is to be done
and t is the temperature in degree celcius at that time

The expression reduces to q = 0.359p/(273+t)
Hold this tight we'll get back to it later on

Now we need only Vdo or the disruptive critical voltage(The
voltage at which corona effect occurs) to calculate the
corona loss

Vdo=go x m x q x rx ln(D/r)
go is the breakdown strength of air.It's about 30KV at
normal temperature.
m is the irregularity or roughness factor of the condutor
which is a given thing.
q is Air density factor which as discussed above
and D and r are the effcetive distance between conductors
and the conductor radius.

No we have all the required things to measure corona loss.
Putting all the values in right place in the Peek's
equation, we get the corona loss.

hope i explained the whole process vividly.

Answer / raghavendran.r

thanx for that detailed explanation, but kindly clarify how
to calculate the power loss due to corona.You have arrived
at Vdo the disruptive voltage where corona begins.but how to arrive at the total power loss due to corona and i think
thats the question that you have also asked.

Answer / remya reghnath

The measurements were performed using a coaxial measurement
arrangement with different bundle and conductor types. The
effects of conductor and bundle type, temperature, applied
voltage and hoar frost thickness on corona losses were
investigated. A two-conductor bundle had corona losses about
2.5...5 times higher than a three-conductor bundle.

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