PSM1700 PsimetriQ user manual
16-3
16.1 Turns ratio
Turns ratio is computed from the real part of the complex
ratio of CH2 divided by CH1 using DFT analysis at the
fundamental frequency (refer to the chapter on gain/phase
analysis for the formulae for DFT analysis). This technique
gives good results even on ‘lossy’ transformers.
The polarity of the windings is indicated by a positive turns
ratio for in phase windings and negative ratio for inverted
windings.
A nominal number of turns may be entered using the
SETUP menu if known and PsimetriQ will then also display
the computed number of turns.
As the inputs are independent of the output it is possible
to energise a third winding when measuring turns ratio, or
only two windings may be used.
To manually connect a transformer for turns ratio, connect
the PsimetriQ output to the winding to be energised, and
the inputs to the two windings for the ratio.
Note that when using the transformer analyser fixture, the
transformer is always energised through the source
resistance.
Pressing ZERO makes the turns ratio read 1:1, and the
computed number of turns equal to the value entered via
SETUP. This allows accurate testing of transformers or
chokes against a known good reference. Press ZERO
followed by DELETE to restore true turns ratio
measurement.