Answer / sripellirajukumar

ya ...this is rajukumar testing engineer...
As per my knowledge ...
it is very important that the secondary of a CT should never
be open-ckted,when the primary is carrying a heavy current.
this is so because
1)if the secondary is open,there is no secondary current and
no secondary flux.The large current in the primary winding
establishes a large primary flux which is unopposed,and this
not only results in huge core losses and excessive heating
of the core,but a high voltage would be induced in the
secondary, this posing a danger to the operator
2)the core gets saturated and
3)the insulation of the windings would be dameged

Answer / max

as CT is connected in series, the if the sec side kept open
high value of the current on te primary side will saturate
the core which might be irrversible and in addition voltage
level at sec side will be very high resulting saftey issues

Answer / max

dude as CT will step down current value it will step up the
voltage hence on the sec side resulting in very high voltage...

Answer / k.narendra

at the primary side the no of turns is less as compared to
secondary, so if we open the secondary the secondary high
voltage at the terminals will exist because we take care
while testing the CT the secondary is closed or not if it
not the person who will at secondary will get effect of voltage

Answer / simon

Since the primary of a CT uses the strength of the magnetic
field around a current carry conductor to induce a current
in the secondary, it can be said the CT"S act as a source of
current. since V=IR and open circuit on the secondary cause
the resistance to approximate to infinite as a result
extremely dangerous level of voltage are induce in the
secondary, this voltage may even jump across leads. danger
may result in excessive heat causing the device to explore,
as well as electric shock of perssonel.

Answer / ayyapss

dear Gatzrulzin ct's primary turns always less than the
sec..In pt's only the turns in the pry is higher than sec.

Answer / ashok

First thing would be explosion of CT. Because of high
voltage generation, it will damage connected metering or
protection relays also.

Answer / sanjay kumar

secondry winding of CT has more no.of turn with less
thickness due to this sec.winding has high voltage with low
current
if secondry winding kept open then sec.voltage will be high
and current zero
high voltage is very dangrous to a person who working near
by & keeping surrounding at high voltage

Answer / prashant

kva(pri)=kva(sec)

if sec is open then current is 0
therefore voltage is infinite
hence spark is produced and short circuit will happen

Answer / gourav

Transformers operate at nearly constant flux. The principle
of transformer states that in order to maintain practically
constant flux the emf induced by primary produces a current
in secondary (if loaded), which thereby opposes the cause
as per Lenz's law. If secondary is kept open, there will be
no opposition to induced emf. The situation worsens if it
is Step Up (CT) as heavy current in primary (load current)
will induce dangerously high emf across secondary leading
to saturation of core as well as hazardous situation for
working personnel.
This can also be explained by B-H curve.

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