Answer Posted / ramesh kumar k
CT & PTs are called as INSTRUMENT TRANSFORMERS as these are
used to measure Currents (CT) and Voltages (PT it is also
called as VT) in circuit mainly in HT lines.
There are nothing but Ammeter/Voltmeters. But the
difference is... Ammeter/Voltmeter are used to measure the
quantities (Current/Voltage) in a 220V line or house hold
applications as these instruments are insulated upto that
level only.
But how to measure the I or V in High Voltage Lines...
there CTs/VTs are used... These have mainly 2 advantages...
There are Primary & Secondary coils in CTs/VTs as in case
of a normal transformer...
1. These Ammeter/Voltmeters can't be used there....
because they are insulated for 230V only (or 3kV at
most)... in we connect these in HT lines... they will burn
out and also dangerous to the persons who are handling
these instruments... So these will give the I or V values
at a reduced voltage levels...
2. As the I or V in the HT lines are heavy... (i.e upto
some thousands of Amps/Volts) we can't manufacture the
general Ammeters/Voltmeters upto that level.. as it makes
costlier.. so we reduce the line values to a measurable
limits (i.e. 5A or 1A or 110V or 100V) by using Induction
principle.
we connect the primary to HT lines and we will get the I or
V at the secondary with a reduced current/voltage level...
so we can connect our normal Ammeters/Voltmeters directly
to measure the I or V in HT Lines...
Ex.:
A CT of 200/1A shows that.. if ammeter connected in
Secondary of a CT indicates 1A that means there 200A is
flowing in the Primary of CT (i.e. in HT line)
in a 132kV / 110V VT, if voltmeter in the secondary of a VT
indicates 110V that means there is 132kV in the primary.
And then these can be used for different purposes like
metering, Protection, Special Protection etc..
| Is This Answer Correct ? | 155 Yes | 3 No |
Post New Answer View All Answers
any one guide me to reduce the power factor of diesel Generator from 0.97 Leg to 0.8 Leg.with out any change in my load.
how to deside the capacity of chock for drive?
How to select transmission line type (i.e. 11kv or 33kv) for new established industries
what are the ''pitting rings''and how cn they be controlled in a series generator
can anyone send me some sample question regarding power grid corp
I am going to appear for the RRB Chennai Section Engineer online exam. Please send me the question papers from 2001 to date to my mail id:upendrakrishna20@gmail.com,plz send me ,or send any other rrb papers plzzzzzzzzzzzzzzzzzz
What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans?
what is booster? and how it is connected in a circuit?
what is physical distance of isolator to VCB in 33/11kv sub stations
can a 150 kva 3 phase 440v/230V delta-wye step down transformer can be use as step up transfoermer with connected loads at 440v side?
WHY THE COLOR OF OUTDOOR TRANSFORMER IS BLUE ONLY???
i have a 1500kVA transformer what is the kWH meter i need to use?
Readings of ER300P Trivector meter
What is an ideal transformer?
how can i improve the power factor in domestic (230v)
