GEK-98834B
11
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The input voltage transformers provide a secondary voltage adequate for the internal
operation at low voltages as well as an electrical insulation with the internal electronic
circuits.
The measuring signals are rectified and are compared with the trip level setting in the
level detectors. Once a fault is detected (overvoltage or undervoltage), the pickup
indicator Vs lights up.
When the fault has been detected, the trip can be instantaneous or time delayed.
Selection of this option is performed by switches located on the front of the relay. If the
fault situation remains once the set time has passed, the relay trips, and the trip indicator
(TRIP) lights up. If the fault disappears, this indicator remains lighted until RESET button
is pressed.
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The single phase versions, different from the three phase versions, may include a filter
for the third harmonic in the stage prior to the rectifiers, as well as the possibility of
selecting the operating mode as undervoltage or overvoltage. As in the three phase case,
the rectifier output signal is compared to the trip level.
Once the pickup has been produced, the operation is similar to the three phase model.
Both versions, single phase and three phase, have a power supply supervision circuit.
If the power supply reduces by 20% of the rated voltage, the relay automatically turns
itself off to prevent incorrect operations.
