TRANSFORMER TESTS VOLTECH AT3600 USER MANUAL
PAGE 7.1.62. VPN 98 - 024 TESTS AND TEST CONDITIONS
1.37. VOCX - O/C VOLTAGE (EXTERNAL SOURCE)
WHERE USED
The AT3600 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 magnetising 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 AT3600.
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, 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 energised winding, with the same test voltage and frequency for each
test.
If there is a magnetising current (MAGX) test which has the same energised 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 5KHz, 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
AT3600s internal generator which can provide up to 270V ac at 40W.
To Next Page
Loading...