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 156
7.38. VOCX - O/C Voltage (External Source)
Where Used
The AT5600 offers two basic alternative ways to confirm that the transformer has
been assembled properly, with the appropriate number of primary and secondary
turns.
Open circuit voltage measurements are the preferred tests for line frequency
transformers, designed to operate over the full extent of the B-H curve, including
the non-linear regions.
(For other transformers, such as pulse transformers and those used in switched
mode power supplies, a measurement of turns ratio is the preferred test.)
Clearly an open circuit voltage test cannot tell you the actual number of turns on a
winding, only the ratio between one winding and the next. You should therefore
also include a magnetizing current test (MAGI or MAGX) in your program, to give
confidence that the absolute number of turns is correct as well as the ratio.
This version of the VOC test uses an external source to provide the test signal
which must be coupled to the tester via a Voltech AC Source Interface (contact
your supplier for details). See the AC Source Interface user manual or the Editor
help system for details of how to configure external AC sources for use with an
AT5600.
Measurement Conditions
Open circuit voltage is measured by applying an AC test voltage (supplied by an
external source) to a selected winding (usually a primary winding), and measuring
the resulting voltage produced on another winding.
If there are several windings to be tested, then the program will execute more
quickly if the following points are observed:
•
Place all the open circuit voltage (VOCX) tests consecutively at the same
point in the program.
•
Use the same energized winding, with the same test voltage and
frequency for each test.
•
If there is a magnetizing current (MAGX) test which has the same
energized winding and the same test voltage and frequency, place this
immediately before the first open circuit voltage test.
The test signal can have a frequency in the range 20Hz to 5 kHz, and an
amplitude from 5V to 600V depending on the type of external source used. The
current rating of a single AC Source Interface is 10A RMS. See also the MAGI
test which uses the AT5600s internal generator which can provide up to 270V AC
at 25W.