Voltech AT360, User Manual

Page: 303 / 470

V
OLTECH
AT
I
U
SER
M
ANUAL
P
AGE
7-5
Recommended Tests
EXAMPLE: Switched-mode DC-DC converter ferrite power transformer
CTY – Continuity
A continuity check is a very quick test to determine if the transformer has been
inserted correctly into the fixture. Used with the ‘Stop on Fail’ feature of the
ATi, the transformer can be re-seated without wasting test time or recording a
‘FAIL’.
R – Resistance
Check the DC resistance of every winding to ensure that the correct diameter
wire has been used and that it is finished or terminated properly. (A poor
solder joint may not show as an out of tolerance inductance, but could lead to
a reduced service life for the transformer).
LS – Inductance (Series Circuit)
As described above, an inductance measurement will confirm that the correct
number of turns has been wound and that the correct cores have been
properly assembled. The test is usually performed on one winding only. If there
is no obvious ‘primary’ winding, use the winding with the greatest number of
turns for the best accuracy and stability.
Q – Quality Factor
Q is the ratio between the imaginary (inductive) and real (AC resistive) parts of
the winding’s complex impedance. Measuring the expected Q figure gives
further indication that the correct wire, turns and cores have been used. Q is
usually measured once only on the ‘primary’.
TR – Turns Ratio and Phasing
Turns ratio checks the correct number of turns has been wound in the right
direction or ‘phase’. Turns ratio should be performed on every winding with the