7.16.7 Unstable TURN
For the transformer with high magnetic permeability magnetic-core，test winding will be unstable.
Solution:
1. Use the TURN_V mode to test winding (voltage-turn mode).
2. Use deviation deduction.
7.16.8 Difference between the first and the second Lx
Because the transformer, with high magnetic permeability magnetic-core, is polarized in the test of
DCR or TURN, the test results of the first and the second Lx test will be quite different.
Solution:
Use 100 ohm internal resistance when testing TURN.
Use 100 ohm internal resistance when testing DCR.
7.16.9 Poor stability of Cx and Zx open test data
If the shielding and ground of test system is not good, it will cause the test value unstable when
testing Cx or Zx.
Solution:
Through a thick metal lead, connect ground poles of the instrument and the scan box as well as the
metal frame of the test fixture together and ground it reliably.
7.16.10 DCR and PS open cannot reach infinite large
Due to the existence of circuit distribution parameter, so the infinite large cannot be displayed when
testing DCR or PS open, it is an normal phenomenon, if user wants to display it, execute the sweep
open correction function on the test fixture.
7.17 User-made test fixture
There are many kinds of transformers, so our company can’t offer a test fixture to each transformer,
which requires user to make a test fixture according to some principles. The followings are caution
items of making test fixture：
1. Use 4-cable measurement method to extend test cable. Don’t use 5.0mm test fixture to hold test
lead.
2. Use multi-strand lacquer cable with good tenacity to be the test extension cable. And use the
stands as much as possible to reduce the resistance of cable.
3. Use high frequency test, and reduce the distribution parameter within extension cable, don’t
use ribbon cable to extend.
4. It is better to use metal frame which is connected to ground pole through a thick metal lead.
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