Answer / saleem

Normoly in HT side 11kv voltsge and less current will be
there But in LT side voltage will be less and current was
very high.So if we change tappings in LT side a huge spork
will come.to avoid this OLTC has to be fixed in HT side
only.

Answer / zia uddin

As we know product of voltage and current on primary side
is equel to product of voltage and current to the second
side it meas their product is same
on high voltage side current is less and on low voltage
side current is high....therefor to minimise spark we
always use high voltage side for tapchanger.

Answer / ravikumar

simply saying HT SIDE MEANS LOW CURRENT SO BY CHANGING
THE TAP ARC PRODUCED IS LESS SO WE CAN RESRICT THE ARC
EG: 33KV -69AMPS
6.6KV-369 AMPS

Answer / kesavan.b trichy,

On Load Tap Changer in a device which works under running
condition to increase or decrease the voltage level of the
Primary & Secondary Side... It is preferable to provide @
HT Side why because in HT Side the current rating is low
while in the LT Side current is so much high.... as we done
the operation of tap changing under loading condition at
the LT Side a huge spark will occur & Damage the
Transformer... That is why only the OLTC is placed on HT
Side

Answer / krishna bagavan

for a transformer, ratio of primary voltage to secondary voltage is equal to ratio of primary turns to secondary turns ie ... v1/v2=n1/n2 ,then v2=v1n2/n1
v1 is incoming or system voltage on which we depend upon & we can not change.now the variables are either n1 or n2 to get required secondary voltage. comparably primary turns are less and it requires less insulation level to change the primary turns,so providing tap changer on primary is better option.

similarly v1/v2 = i2/i1, ie v2 = v1i1/i2, here also vi is system voltage,i1 and i2 are variables. comparably i2 is always higher side and changing primary current with available insulation level is easy,and providing tap changer in primary is the option.

Answer / satyanarayana

generally lt winding is placed next to core so it is very difficult to tap the winding and hv winding is outside so we can easily make tappings

Answer / ponnudurai,tneb,tamilnadu, ind

Hv side less current and then lv side high current at the time of on load Tap changing at hv side less spark will occur if lv side means more spark will occur so it will cause more Damage's in transformer so hv side is the correct position for tap changing the transformer

Answer / srikanth

OLTC(online/load tap changer)is typically used where we
have a variable voltage available on primary side
(11/22/33/66 kv etc.,).The reason behind using OLTC is to
ensure that a proper primary voltage is always
maintained.For example for a 11kv/433v installation which
is located in a industrial/rural area,the voltage on
primary side will never be 11kv.It keeps varying 10 or 9
(peak load time)during day time and may rise to 12,13
during night times(non peak load time).So by having a OLTC
we can raise or lower the volatge accordingly & try
maintaining 11kv/433v.

Answer / guest

Transformer has a lv which is subjected to low voltage
where as
hv wng is subjected to high voltage.
Now on a transmission line voltage vary according to load
demand.
Now if we placed the OLTC in lv side then it is very
difficult to changing the tapping inside the trasformer
accodingly to the load demand.
Now if we placed the OLTC on hv side (which is outer side)
so we can easily change the tapping accordingly the load.
Hence ON LOAD TAP CHANGER PLACE OUTER TO (hv) IN
TRANSFORMER.

Answer / arun babu.s

OLTC,can be installed even at secondary side,but the
problem is, the transformer tank should be bigger size,oil
in the transformer needs to designed accordingly to extend
its di-electric property and the tap contacts to be heavy
comparatively,to withstand the high current in the LT side.
Hence,to avoid so,the OLTC designed at PRIMARY side of the
transformer.

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