OUTDOOR
CURRENT TRANSFORMER
DEAD TANK
VS.
LIVE TANK
OUTDOOR CT
TOP HOUSING / TANK
AT LIVE POTENTIAL
i.e. LIVE TANK
INSULATOR
BOTTOM HOUSING / TANK
AT EARTH POTENTIAL i.e.
DEAD TANK
LIVE TANK CT
DEAD TANK CT
CT CORES WITH SECONDARY
WINDINGS ARE LOCATED
INSIDE THE DEAD TANK
CT CORES WITH SECONDARY
WINDINGS ARE LOCATED
INSIDE THE LIVE TANK
Live Tank CT



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In live tank CT, the core with the secondary
winding is housed in the top tank which is LIVE
(AT HIGH VOLTAGE)
In live tank, the core and secondary winding is
insulated against the high voltage and housed in
the top live tank.
In live tank we insulate the core and secondary
winding.
Only after application of pre-defined insulation on
secondary, primary is wound. Application of
insulation over wound cores is easy.
Dead Tank CT




In dead tank CT, the core and secondary winding is
housed in the bottom tank which is earthed or
DEAD.
In dead tank CT, the primary winding is brought
down to the bottom tank and it is insulated from
the earthed tank and cores.
In dead tank CT, we insulate the primary winding.
It is practically difficult to apply the pre-defined
insulation over the primary because the primary
needs to pass through the wound cores.

Condenser Grading of insulation is easily done.

Condenser grading of insulation is practically
difficult to do.

Insulation is robust and reliable

Insulation is not robust.



Primary winding is of shortest possible length and
its natural shape offers high strength against the
short time current dynamic forces.
Heat generated during short time thermal current is
the minimum (primary copper volume is minimum
and the heat dissipation is fast – the primary
copper is directly in contact with transformer oil)
The transformer is compact and economical
(considering fully oil filled and truly hermetically
sealed CTs)



The primary has to pass through the porcelain
insulator and the larger length of the primary
conductor produces maximum mechanical force
during short time dynamic current which might
damage the insulation.
Heat generated during short time thermal current
is maximum. (Copper volume is maximum and the
heat dissipation is slow as the heat need to conduct
through the major insulation which is normally a
bad conductor of heat)
The transformer is bulky and costly. (considering
fully oil filled and truly hermetically sealed CTs)