Blocking

There is an option to block tripping by ROCOF protection when the measured frequency is within the normal frequency range.

A block, that is no operation, will occur if the measured frequency is inside the normal frequency range and Frequency Block is enabled. Blocking can also occur if the frequency moves into the normal frequency range while a pickup that occurred outside that range is active.

The normal frequency range is determined by the UOF Normal At settings.

The frequency is deemed to be normal when the measure frequency is:

≤ Over Frequency Normal At

And ≥ Under Frequency Normal At

UOF protection is not required to be On for these settings to be applied.

A frequency block will cause any pickup and trip timing that is running to reset.