Tettex 2293 - Page 27

Theory
23
U
1
U
1
N
A
B
C
32A / 50V
or
16A / 100V
n
a
b
c
2
I
U
2
U
2
The measured resistance is calculated as follows:
2
2
I
U
RRR
naan

The transformer transforms any inductive voltage applied to the low side to a higher voltage on
the high voltage side (the resistive voltage drop is not transformed!). For this reason, the device
senses the voltage on the high voltage side and limits it by controlling the supplies on the low
voltage side accordingly.
It is possible that the overvoltage protection of the device triggers on transformers with a
high turns ratio. In this case the user must disconnect the cables from the high voltage
terminals of the DUT to perform a measurement in this mode (B1 or B2).