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.

why we get 2 differnet values for power factor in 2 watt meter method in 3 phase

0 Answers  

Why should we use jelly filled armoured cables in underground Communication system? What is the use of the Jelly? If we go for unarmoured, then what happens?

1 Answers   Prasad Group,

1.Why we use choke?If we use for high starting voltage then different type choke gives different voltage. Is it correct?

2 Answers   Dalkia, Luminous,

What are the industrial applications of Superhetrodyne Receivers ? What are merits & De-merits of SuperHeterodyne Receivers ?

1 Answers   Airtel,

in transformer which grade oil will use?

3 Answers  

Is there any difference between circuit breakers and isolators

7 Answers  

advantages and disadvantages of inverse definite minimum time RELAY

0 Answers  

Why a Permanent Magnet Generator has higher frequency as compared to frequency of main alternator?

0 Answers  

What are the various types of BUSBAR Schemes? explain each

1 Answers   NTPC,

Hi frnds :) plz tell me that i have 100 KVA 3 phase generator so by thumb rule 100*1.4 = 144 amps and generaly we can operate at 80% load...so it will 144*0.8 =112 amps.... so now i m confused about single phase load.....if we use that generator only for single phase the that 112 amps is total single phase load or i can give 112 amps at red 112 amps at yellow and 112 amps at blue.... i mean that total single phase load that 100 KVA generator will take is 112+112+112=336 amp ??

2 Answers   FWO,

How we select the cable rating

1 Answers   BTM, Videocon,

what role neutral plays in electrical circuit? If neutral is not there what will be the effect

1 Answers