Operation mode
Description
If the frequency restores before the module operates, the
reset timer is activated. If the timer reaches the value set
by the
Reset delay Tm Freq
setting, the operate timer resets
and the START and STR_OFRQ outputs are deactivated.
df/dt The function operates independently as the frequency gra-
dient ("df/dt"), rate-of-change, protection function. When
the frequency gradient exceeds the set value of the
Start
value df/dt
setting, the module activates the START and
STR_FRG outputs. The time characteristic is according to
DT. When the operation timer has reached the value set by
the
Operate Tm df/dt
setting, the OPERATE and OPR_FRG
outputs are activated. If the frequency gradient restores be-
fore the module operates, the reset timer is activated. If the
timer reaches the value set by the
Reset delay Tm df/dt
set-
ting, the operate timer resets and the START and STR_FRG
outputs are deactivated.
Freq< + df/dt A consecutive operation is enabled between the protection
methods. When the measured frequency is below the set
value of the
Start value Freq<
setting, the frequency gradi-
ent protection is enabled. After the frequency has dropped
below the set value, the frequency gradient is compared to
the set value of the
Start value df/dt
setting. When the fre-
quency gradient exceeds the set value, the module activates
the START and STR_FRG outputs. The time characteristic is
according to DT. When the operation timer has reached the
value set by the
Operate Tm df/dt
setting, the OPERATE and
OPR_FRG outputs are activated. If the frequency gradient
restores before the module operates, the reset timer is acti-
vated. If the timer reaches the value set by the
Reset delay
Tm df/dt
setting, the operate timer resets and the START
and STR_FRG outputs are deactivated. The OPR_UFRQ out-
put is not active when this operation mode is used.
Freq> + df/dt A consecutive operation is enabled between the protection
methods. When the measured frequency exceeds the set val-
ue of the
Start value Freq>
setting, the frequency gradient
protection is enabled. After the frequency exceeds the set
value, the frequency gradient is compared to the set value of
the
Start value df/dt
setting. When the frequency gradient
exceeds the set value, the module activates the START and
STR_FRG outputs. The time characteristic is according to
DT. When the operation timer has reached the value set by
the
Operate Tm df/dt
setting, the OPERATE and OPR_FRG
outputs are activated. If the frequency gradient restores be-
fore the module operates, the reset timer is activated. If the
timer reaches the value set by the
Reset delay Tm df/dt
set-
ting, the operate timer resets and the START and STR_FRG
outputs are deactivated. The OPR_OFRQ output is not active
when this operation mode is used.
Table continues on the next page
1MRS759142 F Protection functions
REX640
Technical Manual
923
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