Answer / m.k. mishra (mpptcl)

to discharge the induced high potential developed in the core due to capactive effect , the capacitance is formed between winding insulation and core. for more details contact me...

Answer / rvg.msceb

i dont think circulating current will flow through earthing,
since the voltage is lesser.It can only heatup core and
insulation.

Core earthing doing for the purpose of operator
protection.incase of any insulation leakage or damage, the
operator will get shock hazard.This can be saved by earthing.
More over the this will ensure the ELR to opearte in case
any earth leakage from transformer.

Answer / amin

Power transformer cores are constructed of sheets of grain-oriented silicone steel, designed to have a very low resistance to the flow of magnetic flux (reluctance). These sheets of silicone steel have a very thin coating of varnish or enamel on them so they are magnetically coupled, but electrically separate. The transformer’s windings are wound around the core, with the low-voltage winding wound against the core and the high-voltage winding wound over it. This arrangement reduces the dielectric stress between the low- and high-voltage windings and between windings and core. Transformers will be wound as core-form or shell form types.

Because of the construction of the transformer core/winding assembly, there can be high potentials induced into the core, causing partial discharges which will damage the transformer. The core ground diverts this voltage safely to ground. The core ground also provides a low-resistance path to ground if there is a short circuit between the winding and the core, allowing protective relaying to detect it. The core ground may be brought out to a separate, external bushing or it may be connected internally, with cost being the driving factor as to its location. As it is with most investments, you get what you pay for.

Answer / moses

if the core is left unearthed then there is a possibility
for the core to acquire charges to get into a potential
which may cause insulation failure between the leads of the
transformer to the core
so the core is earthed in transformers

Answer / mustafa

In isolation transformers the shield in the windings is
earthed in order to avoid spikes or noise signals at the
output of the transformer

Answer / baloch

Core of Transformer is being Earthed, because if you see the
Hysteresis Curve, flux doesn't decay to zero. If there is
some flux, it means there must be some amount of voltage and
hence the current. To avoid this shock, core is needed to be
earthed. It doesn't affect in Distribution Transformer due to
low voltage, but in case of power transformer it does.

Answer / s. rambabu

Core is magnetic one , When voltage is applied, circulating
currents will flow in magnetic core causes overheating. To
discharge these currents core is to be earthed

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