> 3. The secondary should be shunted by a bi-directional TVS
> diode (1.5KExxx
> type works well) in case the burden resistor opens and to
> soak up starting
> current surges when you turn on the product. Pick a
> comfortable voltage for
> whatever you are driving with the CT for the TVS. I usually
> use the 6.8V
> version.
>
> 4. Rectifying the output directly is not a good idea,
> especially with a half
> wave rectifier. There are two reasons for this. The diode
> will leave the
> secondary unterminated for half of the cycle, which will
> overvoltage zap the
> diode if a burden resistor is not used before the rectifier. The other
> problem is the diode offset voltage contributes a large error at low
> currents, even with Schottky diodes. An op-amp "perfect
> rectifier" circuit
> is recommended for pre-pic detection.
>
> Regards,
> Edward Gisske, P.E.
> Gisske Engineering

Hi Edward,

I take it a by TVS you mean "Bi-Directional Transient Voltage Suppressor",
yes ?
I've never used one of these before.  Had to check Google to find out what a
"TVS" was ;)

Excuse my ignorance, but how do you wire that into the secondary side of a
CT ?
By "shunted", I assume that just one goes in parallel with the burden
resistor (similar to an MOV) ?  TVS come in Watt ratings as far as I can
tell from my limited Googling so far.  How come 6.8V ?, and what watt rating
do I need ?  I know I will be pulling 5A on a 50:5 or what ever, but what is
the resistance of a TVS to calculate Watt rating ?  Or am I missing
something here ?

Would an MOV do the job ?

Rgs
Ian

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