Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Current vs. Voltage Transformer
Unread postPosted: Thu Dec 23, 2004 11:06 am
I've been looking around the internet and have so far been unsuccessful in finding info on the differences
between current and power transformers (3-phase).
My guess is that a current transformer steps-up current by
having less secondary windings... and a power transformer steps-up voltage by increasing the number of secondary
windings when compared to the primary windings.
This explanation seems a little too simple!
thing i was wondering about, is that a superior of mine was telling me that when dealing with current
transformers, it's important not to short circuit the terminals (or open circuit them, i can't remember which
one)... when i asked why this was the case, he said he wasn't sure, but that it caused arcing between the
Would there be a similar issue to consider in power transformers?
Does this make any
sense!? I would really appreciate a response.
Thanks for your help
Unread postPosted: Mon Jan 24, 2005 2:31 am
A voltage transformer is used to either step up or
step down a voltage.
That is usually what people refer to when talking transformers.
transformer, or "CT" as it is sometimes called, is usually used when measuring large currents. A good example of
this is a clamp on ammeter. When measuring a 150 amp current there is no way that 150 amps is flowing in the
meter. The meter steps the current down proportionally to the current you are measuring in the wire the meter is
clamped around. CT's are designed to operate with the secondary shorted.
The book I have(Delmar's Standard
Textbook of Electricity) says that...
"The secondary winding of a CT should never be opened when there is
power applied to the primary. This will cause the transformer to produce a step-up voltage that could be high
enough to kill anyone who comes in contact with it."
When CT's are used 1 loop of wire goes through the
core of the CT. Remember, the CT secondary is designed to be used short circuited. The secondary of the CT has
several windings.....when disconnected, the CT turns into a step up transformer. If the voltage you are measuring
is 480 and the CT secondary has 50, 100, or even 200 turns.....you now have a 1:50, 1:100, or 1:200 step up
transformer. That is going to hurt if you get across it.
Basicly, if you disconnect the secondary of a CT,
be prepared to get the heck knocked out of you. :wink: