The Open Circuit Voltage across a winding may be tested. An AC voltage (from an external source) is applied across the primary winding and the resulting voltage across the chosen secondary winding is measured.

This 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.

On selecting "VOCX Open Circuit Voltage (External Source)" from the available tests window, a form fill-in dialog box will be displayed:

To program the test :

Enter the test voltage and frequency at which the test is to be carried out.
Note that the Measure button cannot be used to determine any of the required test parameters.
Select either AC Voltage, DC Voltage or Mean sense, RMS scaled measurement by clicking on the relevant button.
Select the integration time required.
'Medium' is the default setting. 'Long' will give more stable readings (for tighter limits) at the expense of an increased test time, and 'Short' will test at the maximum speed, but may give a slightly noisier reading.
Enter the terminal names for the Energized High and Low Terminals.
Click on the arrow to the right of the fill-in box, and you will be provided with a choice of available terminals; double-click on the one required.
Similarly, enter the names for the Measured Terminals.

Set the voltage limits.

%	Enter a nominal value and then the limits as negative and positive percentage values.
><	Enter minimum and maximum values.
>	Enter just a minimum value.
<	Enter just a maximum value.
Note that the Measure button may be used here as outlined in section 3.9.

Polarity testing can be included in the test by selecting either positive or negative radio buttons to test against. Here the polarity test will produce either Pass or Fail results. Polarity testing is not possible if the source type is 'Manual Source / Line Supply'. (For ac measurements, use the positive polarity when the measured winding has the same phase as the energized winding, use the negative polarity when they have opposite phases.)
Select OK. The test specification will be displayed in the program window on the screen.

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