[Boatanchors] PTs and CTs

[J Forster]

RBethman wrote:

> Both potential transformers, (PTs) AND current transformers, (CTs) are
> used for providing metering, operational displays, AND safety relay
> systems on Power Systems.
>
> Since we are looking at a 15:1 CT for metering, AND there MUST be a
> potential for current to flow - THEN -there MUST be a 15:1 Voltage
> present in this proposed system.

Yes, there is a voltage stepup from the primary to the secondary, but
because a transformer must have watts in = watts out (ignoring small losses)
the voltage across the primary is 1/15 of the voltage across the secondary.
If the CT is properly connected to a meter, the secondary voltage is small.
Only if the secondary is open circuited, will large voltages appear there.

> if the Voltage involved is 120VAC - THEN the potential available at ONE
> end of the CT system is FIFTEEN times the voltage used at the meter end.

ONLY if the secondary is OC.

> That is PRECISELY - why - I am promoting the use of a shunt!

They are MUCH more dangerous.  See
http://en.wikipedia.org/wiki/Current_transformer  for example.
-John

> No voltage increases are POSSIBLE!
>
> Bob - N0DGN