Answer / sheril

because th swiching frequency will be low compared to others
like scrs

Answer / jaipal

Transistors are not used as switching devices in the
elcectrical circuits because they can not with satnd for
high power ratings.

Answer / harsh zala

We can use transistor as a switching device but only for
low voltage application(for e.g electronic ckt)

If we want to use it in an electrical ckt, then we have to
go for higher current capacity, which are available upto
certain extent, but other switching devices are far more
cheper and responds good compare to it.

As we know it is current controlled device, so if we apply
large voltage diffrance or higher base current it can falsy
trigger, that is not desirable.

Answer / nakul khond

for using it as a switch we need to bias it properly we need
to use vcc,vbe this is very complicated and costly
instead we can use diode as a switch no need to bias easy
and cheap switch

Answer / biraj kundu

transistor are mainly current driven whle for switching are
done at high frequency and high voltage. thus devices like
SCR,IGBT,MOSFET,etc are used.
transistors are employed in small ckts

Answer / gnanbalaji

The above said answers are wrong.Recently power transistors
were developed.They can be used.Due to secondary breakdown,
conduction losses,they are not used frequently.Due to small
reverse leakage current they will turn ON automatically.

Answer / niranajn

since a transistor is bipolar as the conduction is due to
both electrons and holes

Answer / dr.anil

Actually, The question is incorrect. All of the transistors
can be used as a switch because transistors has current
on/off properties.There are 2 types of transistors one is
BJT(3 Terminal) and FETs(4 Terminal). BJT has low conduction
loss but has high switching losses whereas a FET
specially(IGBT or MOSFETs) have low sitching losses. That is
why MOSFET is preferred as switches instead of BJT in High
power, High Frequency applications.

Answer / amol

old days transister has hi switching &conduction loss,but
now days transister IGBT are used.

Answer / sathish.n tessolve

Hi Friends

The reason why we are not using the transistor as
switching device because there is a chance of current flow
from VCC to ground when the transistor is ON.So the
transistor take more power.But this is never happen in the
CMOS device because only one transistor is get ON at a time.

design of IGBT firing circuit for 11KV

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