V
OLTECH
AC
I
NTERFACE
U
SER
M
ANUAL
98-072
ISS
7
PAGE
28
3.2. C
URRENT
S
ENSE
M
ETHOD
The AC Interface measures current by using a current sense method.
The current is measured via a current transformer, which is fitted to the AC Interface.
You may enter the current transformer ratio into the dialogue box, so that the AT3600/AT5600 will report the
correctly scaled current.
The CT10-20 plug in module supplied with your AC Interface has a ratio of 1 primary turn to 20 secondary
turns (1:20).
The “10” represent the 10 Amps max that the primary (UTT) current can carry
The “20” represents the ratio of the CT transformer. This CT will scale these larger currents down ( e.g., 5
Amps to 0.250 Amps) so that the AT can measure it.
Once this ratio is set, you program the test and limits in the real UUT current – the Editor and AT will
manipulate the results to give a true UUT current.
Most customers will use the supplied CT10:20 plug in module, so the default settings of 1: 20 should be
used. Users should be aware that this means smaller real currents on your UUT (<50ma) will also be scaled
down x 20 so results will be more subject to noise floor.
Current sense is much preferred over a voltage sense method, as the current sense method is much more
accurate and more robust in an industrial environment.
Voltage sense methods are typically more susceptible to environmental electromagnetic noise.
