446
19.
NOTES ON HIGH VOLTAGE TECHNIQUE
bright illumination appears all along the wires and the noise
increases noticeably. It is impossible to give a general value for'
this voltage, Where'corona begins, since it depends on many factors,
but to give the reader a rough idea, one may say that for a par— '
'
ticular transmission line and for certain conditions it amounted
value between 100 and 200 kV.
With still higher voltages,
the intensity of the light increases, an odor of ozone and nitrous
oxide is noticed and the power losses increase rapidly.9
The
breakdown occurs rst near the surface of the conductor, since
the electric eld intensity is greatest there.
Since ionized air is
conducting, the size of the conductor is effectively increased and
gradient in air nearby is reduced below the breakdown
_
point.
discharge, then, extends to a denite distance from
the Wire at a xed voltage. When the voltage is sufciently high,
a spark-over occurs at Some chance place between the conductors.
.]
If the wires aresuiciently close together, spark-over will occur
,
rst and visible corona never appears.
With the wires far apart,
the corona forms rst.
to the'differences of mobilities of the
ions, the corona losses
._
are usually greater between a small and a
large conductor When the latter is negative than when it is positive. é_
'
To reduce cOr0na losses, high voltage machines should be'used
'
ina—dry, warm rôom,free from dust .;Rounded Corners and smooth Ÿ
and kettle3;of
7
,
metal
is
Were1ntendedfork1tchen
use areuseful m h1ghvoltage 1nstallauam The voltageatwhlch
C®ronastartsmay beralsedbÿ ; 1ncreasmgthe d1ameterofthe
neartheWlreandtheleSSthechanœofbreakdown0nd1rectprO
at25Cand76œnt1meœrsressureForseveralhundred
k®V®1tïeadWlres21nchbrasstubesmaybeusedCmonacan
19.
NOTES ON HIGH VOLTAGE TECHNIQUE
bright illumination appears all along the wires and the noise
increases noticeably. It is impossible to give a general value for'
this voltage, Where'corona begins, since it depends on many factors,
but to give the reader a rough idea, one may say that for a par— '
'
ticular transmission line and for certain conditions it amounted
value between 100 and 200 kV.
With still higher voltages,
the intensity of the light increases, an odor of ozone and nitrous
oxide is noticed and the power losses increase rapidly.9
The
breakdown occurs rst near the surface of the conductor, since
the electric eld intensity is greatest there.
Since ionized air is
conducting, the size of the conductor is effectively increased and
gradient in air nearby is reduced below the breakdown
_
point.
discharge, then, extends to a denite distance from
the Wire at a xed voltage. When the voltage is sufciently high,
a spark-over occurs at Some chance place between the conductors.
.]
If the wires aresuiciently close together, spark-over will occur
,
rst and visible corona never appears.
With the wires far apart,
the corona forms rst.
to the'differences of mobilities of the
ions, the corona losses
._
are usually greater between a small and a
large conductor When the latter is negative than when it is positive. é_
'
To reduce cOr0na losses, high voltage machines should be'used
'
ina—dry, warm rôom,free from dust .;Rounded Corners and smooth Ÿ
and kettle3;of
7
,
metal
is
Were1ntendedfork1tchen
use areuseful m h1ghvoltage 1nstallauam The voltageatwhlch
C®ronastartsmay beralsedbÿ ; 1ncreasmgthe d1ameterofthe
neartheWlreandtheleSSthechanœofbreakdown0nd1rectprO
at25Cand76œnt1meœrsressureForseveralhundred
k®V®1tïeadWlres21nchbrasstubesmaybeusedCmonacan