ABB RELION 620 Series Technical Manual page 329

1MAC504801-IB E
620 series ANSI
Technical Manual
Operation mode
Freq> + df/dt
Freq< OR df/dt
Table continues on next page
Protection functions
Description
A consecutive operation is enabled between the
protection methods. When the measured frequency
Pickup value Freq>
exceeds the set value of the
setting, the frequency gradient protection is enabled.
After the frequency exceeds the set value, the
frequency gradient is compared to the set value of
Pickup value df/dt setting. When the frequency
the
gradient exceeds the set value, the module activates
the PICKUP and PICKUP_FRG outputs. The time
characteristic is according to DT. When the operation
timer has reached the value set by the
setting, the TRIP and TRIP_FRG outputs are
activated. If the frequency gradient restores before
the module trips, the reset timer is activated. If the
timer reaches the value set by the
dt setting, the trip timer resets and the PICKUP and
PICKUP_FRG outputs are deactivated. The
TRIP_OFRQ output is not active when this operation
mode is used.
A parallel operation between the protection methods
is enabled. The PICKUP output is activated when
either of the measured values of the protection
module exceeds its set value. Detailed information
about the active module is available at the
PICKUP_UFRQ and PICKUP_FRG outputs. The
shortest trip delay time from the set
Trip Tm df/dt is dominant regarding the TRIP output.
The time characteristic is according to DT. The
characteristic that activates the TRIP output can be
seen from the TRIP_UFRQ or TRIP_FRG output. If
the frequency gradient restores before the module
trips, the reset timer is activated. If the timer reaches
the value set by the Reset delay Tm df/dt setting, the
trip timer resets and the PICKUP_FRG output is
deactivated. If the frequency restores before the
module trips, the reset timer is activated. If the timer
Reset delay Tm Freq
reaches the value set by the
setting, the trip timer resets and the PICKUP_UFRQ
output is deactivated.
Section 4
Trip Tm df/dt
Reset delay Tm df/
Trip Tm Freq or
323