Voltech AT5600, Руководство пользователя

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C H A P T E R 7 – T E S T S A N D T E S T C O N D I T I O N S
AT5600 User Manual 98-119 issue 14
Page 112
7.13. TR - Turns Ratio
Where Used
The AT5600 offer two basic alternative ways to confirm that the transformer has
been assembled properly, with the appropriate number of primary and secondary
turns.
Turns ratio is the preferred test for signal, pulse and switched mode power
transformers, where the normal operating conditions require only small excursions
of the B-H curve, never extending beyond the linear regions.
(For line frequency transformers, designed to operate over the full extent of the B-
H curve, including the non-linear regions, the preferred method is to use an open -
circuit voltage test to check for the correct numbers of turns on each winding.)
Clearly a turns ratio test cannot tell you the actual number of turns on a winding,
only the ratio between on the primary and secondary. You should therefore have
at least one inductance test in your program to give confidence that the absolute
number of turns is correct as well as the ratio.
Measurement Conditions
To measure turns ratio, a test source voltage is applied to one winding, the
energized winding, and the voltages across two other windings (one of which may
also be the energized winding) are measured using harmonic analysis. The turns
ratio is measured by dividing one measured voltage by the other and making a
compensation for the effects of winding resistance.
It is recommended that you choose the winding with the highest number of turns
as the one to be energized. A possible exception to this rule is when you wish to
measure the ratio between two windings which should be accurately matched at
1:1. In this case it may be better to energize a third winding with a lower number
of turns, to ensure that any measurement errors apply equally to the two windings
under test.
You can specify the signal to be applied to the energized winding to have a
frequency in the range 20Hz to 3MHz, and amplitude from 1mV to 5V. The
recommended test conditions depend on the inductance of the energized
winding; they are given in the table below assuming that the energized winding is
the one with the highest number of turns: