transformer question ..

[Paul]

Hi

A quick question about transformer. I read in the some book that transformer
really only works for AC waveform. Is that true? I used to think that it works
for DC as well? Thanks.

V1I1=V2I2

 

[Henry Kolesnik]

It'll work with short DC pulses but is generally an AC device. If a pulse
lasts too long there's no change in magnetic field and trasnformer action
ceases, while on AC the magnititudew and polarity is contstantly varying.

--
73
Hank WD5JFR
"Paul" <paulw@mmail.ath.cx> wrote in message
news:3ba4d769.0408150809.35fdb012@posting.google.com...

Hi

A quick question about transformer. I read in the some book that
transformer
really only works for AC waveform. Is that true? I used to think that it
works
for DC as well? Thanks.

V1I1=V2I2

 

[John Popelish]

Paul wrote:

Hi

A quick question about transformer. I read in the some book that transformer
really only works for AC waveform. Is that true? I used to think that it works
for DC as well? Thanks.

V1I1=V2I2

The voltage out of a transformer is a result of a rate of change of
the magnetic field passing through the coils. To produce DC, the
magnetic field would have to keep changing in the same direction,
indefinitely. Since magnetic core materials saturate at much less
than infinite flux, no real transformer can produce DC. The general
rule is that transformers (and any inductive component) supports an
average of zero volts drop (the volt seconds on one direction must be
followed by the same number of volt seconds in the opposite direction,
each cycle). However, there is no requirement that the average
current be zero, so inductive components, including transformers can
pass DC current. A non zero current just implies that the average
flux is not zero.
--
John Popelish

 

[Graham Knott]

Paul wrote:

Hi

A quick question about transformer. I read in the some book that
transformer really only works for AC waveform. Is that true? I used
to think that it works for DC as well? Thanks.

V1I1=V2I2

--
Have a look at
http://homepage.ntlworld.com/g.knott/elect102.htm