Hi tkvenki,
It is difficult to see where your problem lies.
In some diagrams they have ashown a 1:1800 CT....And they have
connected the "1800" part to the evaluation board. But i doubt
connecting the CT like this.
I assume that when you say a CT you mean a current transformer.
I further assume that by current transformer you mean like this:
**broken link removed**
This unit is intended to surround one of the current carrying
conductors from the primary current source. As you can see there are
only two connections on this unit. These two connections are for the
analogue indicators.
It is toroidally wound with many many turns, and a fairly high internal
impedance. It is intended to give a (relative) reading of current
at its output terminals.
This output current is intended to be consistent whether one or many
analogue devices are placed in series as a load across its terminals.
The load across its terminals is not intended to alter the current
reading that it puts out ... unless the output impedance gets
abnormally high, such as an open circuit.
It achieves this by having a very high available output voltage, and also
a fairly high internal resistance. The output voltage is normally kept low
because of the analogue devices that it is running.
The result is that many analogue devices, usually meters, can be put
in series, without affecting their readings (very much).
The down side is that one must take special care to avoid an open
circuit in the indicator line, because this can cause very high
voltages to appear in that circuit.
Such high voltages are not usually expected in instrument panels,
and can be lethal, or cause damage to insulation or other parts of
the instrument panel.
As the current feeding these devices is limited it is permissable to
short circuit the output terminals without worrying, but an open
circuit is only alright if the primary current carrying conductor
cannot carry any current, because very high voltages can occur.
This is an old fashioned set-up, and may cause confusion for some
one who is not familiar with the way that the meters are set up,
sometimes with long runs of cabling, which don't seem to have their
resistance taken into account at first sight.
Google has no definition for an evaluation board, so i can't really
help much there.
But i will try to help with the calibration.
The CTs and the meters usually come as a set, but they don't have to.
I assume the analogue indicators are meters.
If the meters are for use with a CT then there should be an indication
around FSD of the CT output current, which should be marked on the CT.
On this meter there is a little tiny '5' marked discretely on the
outer edge, just by the '100' mark.
That is because this meter is for a CT output of 5 Amps at its
intended high reading, when its primary current carrying conductor is
passing 100 Amperes.
Accordingly the meter or meters to be used with this CT would be bench
set to read in that position with 5 Amperes going through the meter.
This would be adjusted by shunts within the meter itself, not
externally. Externally the meters would just be wired in series with
each other, across the CT terminals. Some meters may be quite a way
off, and the instrument mechanic should be made aware of the dangers
and should take precautions as necessary.
So:
The meters are wired in series, the current through each is the same.
( for the given CT )
I hope this helps, but it is difficult to follow your request.
Best of luck with your arrangement, John