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Time delayed phase overvoltage
protection (TOV)
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The TOV--TRIP and TOV--TRPE output signals changes from logical 0 to logical 1 if
at least one of the logical signals TOV--STUL1N or TOV--STUL2N remains equal to
logical 1 for a time longer than the set value on the corresponding timer. The signal
TOV--TRPE will be high, to indicate that the overvoltage protection caused the trip.
Any signal connected to the TOV--BLOCK input blocks the operation of the time de-
layed overvoltage protection. Similarly any signal connected to TOV--BLKTR will
block the trip output from the time delayed overvoltage protection.
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The parameters for the time delayed phase overvoltage protection function are set via
the local HMI or PST (Parameter Setting Tool). Refer to the Technical reference man-
ual for setting parameters and path in local HMI.
All the voltage conditions in the system where the overvoltage protection performs its
functions must be considered. The same also applies to the associated equipment, its
voltage-time characteristic.
The overvoltage protection should be set higher than the expected maximum system op-
erate voltage that is in a particular part of a network. A safety margin of at least 10%
should also be considered due to the inaccuracies in the instrument transformers, calcu-
lation methods, and the inaccuracy of the measuring elements in the terminal.
144
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