C H A P T E R 1 4 - A T E D I T OR
AT5600 User Manual 98-119 issue 14 Page 363
14.6.35. LVOC – Low Voltage Open Circuit
Applying an AC voltage to the primary of the transformer will produce an AC
voltage in the secondary. Low Voltage Open Circuit measures the ‘open circuit’
voltage produced when the specified test signal is applied.
The secondary voltage may be in phase with the primary voltage or it may be
anti-phase depending on the winding and the termination of the windings.
To program the test:
1. Enter the required test signal.
2. Choose the integration period (normally ‘medium’). See 7.3 Explanation of
Integration.
3. Enter the terminals to be used.
4. Energized terminals: The terminals where the test signal will be applied.
This is normally the winding with the greatest number of turns.
5. Primary terminals ‘High’ and ‘Low’: The zero phase reference terminals
which are often the same as the energized terminals.
6. Secondary terminals ‘High’ and ‘Low’: The turns ratio and polarity
measurement will be made between the primary and secondary terminals.
7. Choosing the test limits.
The test limits can be:
% A nominal value together with + and – percentage limits.
>< Minimum and maximum values
> A minimum value only
< A maximum value only
The Measure button may be used here as outlined in section 14.5.9.
Test limits should be set as close as possible to the nominal value in order to
detect faults. A typical tolerance would be 5%.
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