Lvoc - Low Voltage Open Circuit - Voltech AT5600 User Manual

C H A P T E R 7 – T E S T S
7.39. LVOC – Low Voltage Open Circuit
Measurement Range
100V to 650V
Where used
The low voltage open circuit test is used to confirm that windings have the correct
ratio of turns between them, and that the phasing of the windings is correct. This
test is used for signal, pulse and switched mode power transformers where the
normal operating conditions require only small excursions of the B-H curve, never
extending beyond the linear region. On the AT5600, high voltage open circuit
tests (VOC or VOCX) are available for testing line frequency transformers at their
operating point (up to 270V, 1 kHz and 2A). To measure the voltage ratio rather
than the voltage, see the test TR – turns ratio.
Measurement conditions
To measure low voltage open circuit, the test signal is applied to one winding
called the energized winding. The voltages across another winding (or the same,
energized winding) is measured. The low voltage open circuit measurement is the
RMS value of the voltage measured and can be an AC or a DC voltage. It is
recommended that you choose the winding with the highest number of turns as
the one to be energized.
AT5600 User Manual 98-119 issue 14
A N D T E S T C O N D I T I O N S
Test
Voltage
1mV to 5V
Test
Basic Accuracy
Frequency
20Hz to 3MHz
AT Secondary
measurements
In phase
Anti-phase
0.10%
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