User Manual SM6025
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accuracy is inferior to four-terminal measurement in LCR manner. Using the built-in bias voltage source
of SM6025 , bias test can be made for transformer winding.
It is not recommended to replace the test fixture with independent connector, because the shield terminal
of four test terminals should develop a reliable short circuit to form four-terminal pair.
Figure 5-17 Schematic diagram for transformer test connection
In figure 5-17,
the winding connected to the Hpot terminal is defined as primary, winding A; the
winding connected to the Hcur terminal is defined as secondary, winding B
.
Before transformer test, appropriate test level and test frequency should be selected.
After selecting the parameter and connecting the transformer test fixture, conduct short circuit and open
circuit reset. When in short circuit reset, if the primary parameter is L2A, Hpot terminal should realize
reliable short circuit with low terminal; if the primary parameter is L2B, Hcur terminal should realize
reliable short circuit with low terminal.
5.6.1 Primary and secondary inductance L2A, L2B
After connecting the test fixture and the transformer according to figure 5-17, primary inductance can be
measured if the primary parameter selects L2A and secondary inductance can be measured if the
primary parameter selects L2B.
When selecting L2A, the signal source exists in transformer primary polarity;
When selecting L2B, the signal source exists in transformer secondary polarity.
5.6.2 Turn ratio and polarity measurement N, 1/N
SM6025 adopts the method of voltage ratio to measure the turn ratio directly. When the secondary
parameter selects N or 1/N, it can measure the turn ratio. When N or 1/N appears to be negative,
indicating that it is the non-dotted terminal of the transformer connected to Hcur and Hpot terminal.
Figure 5-18 Direct measurement of turn ratio by voltage ratio method
When the measurement parameter is L2A-N, N is the turn ratio of primary to secondary;
