3.4.36 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 antiphase depending on the winding and the termination of the windings.
To program the test:
- Enter the required test signal.
- Choose the integration period (normally ‘medium’).
- Enter the terminals to be used.
- Energized terminals: The terminals where the test signal will be applied.
This is normally the winding with the greatest number of turns.
- Primary terminals ‘High’ and ‘Low’: The zero phase reference terminals which are often the same as the energized terminals.
- Secondary terminals ‘High’ and ‘Low’: The turns ratio and polarity measurement will be made between the primary and secondary terminals.
- 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 |
Use the Editor�s �measure� button (together with a sample part) if you are unsure of the nominal value.
Remember to click on the units of limits (mV or V) when entering absolute values as limits.
Test limits should be set as close as possible to the nominal value in order to detect faults. A typical tolerance would be � 5%