VOLTECH AT3600 USER MANUAL PROGRAMMING TESTS
TEST PROGRAM EDITOR VPN 98 - 024 PAGE 3.4.21.
What happens if I set both absolute limits for both primary and secondary
windings?
If you want to detect up to a 10 turn error on the primary and 1 turn on the secondary
in the above example, set 91/2 (pri) and 1/2 (sec).The tester uses the equivalent ratio
limits: 21.95 and 18.05. Setting both limits WIDENS the limit to allow for an
error of 10 Turn on the primary SIMULTANEOUSLY with 1 turn on the
secondary.
i.e. to allow 190:11 (17.27) and 210:9 (23.33).
Notice that these limits will NOT detect just a 1 turn error on the secondary because
you have now chosen limits to allow for errors on both primary and secondary,
resulting in a broader tolerance on the absolute ratio.
How so I set limits that will detect a 1 turn error in either the primary or
secondary winding?
To do this you must set limits that will detect the smallest possible error. This will be
due to the 1 turn error being on the winding with the largest number of turns.
In the above example then, set absolute limits of ½ turn (pri) and 0 turn (sec). (
Remember to use the n-1/2 rule).
The equivalent limits used by the tester will be:
20.05 and 19.95
This will certainly detect a 1 turn error in the primary, but because of the physical
errors already described these limits may be too severe for a normal good part. This is
why a combination of inductance and turns ratio tests are normally used to confirm
the correct assembly of transformers.
The polarity test may be selected as (+)ve, (-)ve or no test. To measure the exact
interwinding phase angle use the PHAS test.
Use the PC Editor’s ‘measure’ button (together with a sample part) if you are unsure
of the nominal value.
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