Answer / vishal shah

hello Mr. V Ram
Windin Temp. Can be measured with the help of Inbuilt-
Thermal Image type WTI (Winding Temp. Indicator)

The Winding is the component with highest temperature
within the transformer and, above all, the one subject to
the fastest temperature increase as the load increases.
Thus to have total control of the temperature parameter
within transformer, the temperature of the winding as well
as top oil, must be measured. An indirect system is used to
measure winding temperature, since it is dangerous to place
a sensor close to winding due to the high voltage. The
indirect measurement is done by means of a Built-in Thermal
Image.

Winding Temperature Indicator is equipped with a specially
designed Heater which is placed around the operating
bellows through which passes a current proportional to the
current passing through the transformer winding subject to
a given load. Winding Temperature is measured by connecting
the CT Secondary of the Transformer through a shunt
resistor inside the Winding Temperature Indicator to the
Heater Coil around the operating Bellows. It is possible to
adjust gradient by means of Shunt Resistor
In this way the value of the winding temperature indicated
by the instrument will be equal to the one planned by the
transformer manufacturer for a given transformer load.

logon to www.scientificcontrols.com for further details
regarding OTI & WTI

Answer / sripellirajukumar

hi this is rajukumar
transformer testing engineer
actually in power transformer we will be using one sensor
that is WTA ..windidng temperature indicator..by that device
we can check the winding temperature of transformer.. when
the fault occures the winding temperature much be rised....
at that fault time this WTA will sence the obnormal
temperature of winding then it will send trip signal to the
ckt breaker...
but in heat run test we can not find the winding temperature
..but we can find how much the transfomer is heating on full
load current...



thanks..

Answer / pragati

hi I am Pragati

after reading those answers i found two keywords which are
RTD & thermostat.

RTD(resistance temperature detector) is used only to display
the temperature of winding. PT100 is one of RTD in which at
0degc the resistance is 100ohms. As temp. increases the
resistance increases linearly.

other is thermostat, it is an thermal switch.
DMP is one of thermostat which is having particular temp.
rating like 150deg C or 160 deg C and so on
as temp. of winding crosses the rated the switch is operated
and circuit is disconnected. This will protect our winding
from burning.

so if only display of temp. purpose we can use RTD & for
protection from burning we can use thermostat.

Answer / sunil

winding temp means temp. of oil plus additional temp
measure due to load

Answer / arjunkumar

Mr Vishal u r write but i have confusion on equation

WTI= (Ambient Air Temperature) + (Top Oil Temp. Rise.) +
1.1 X GRADIENT

here what is GRADIENT?CAN WE COUNT GRADIENT VALUE?

IF U HAVE ANY IDEA THEN HELP ME TO ACHIEVE ANSWER.

Answer / ashokreddy r

sumpners test

Answer / shesh mani tiwari

winding gradient = (Iph)2 X RESISTANCE/OIL EXPOSED SURFACE
AREA.

Answer / reddy

temparature sensors may be used.. sumpners test is heat run
test.. mean without any external loading, full load
testing of T/F

Answer / v_ram

hi ashok reddy...can u explain it?

Answer / purushmallya

Generally RTDs i.e Resistance Temperature Detectors are
kept in core or winding which gives u temp of that spot.

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