ABB RELION REX640 Technical Manual page 848

Section 4
Protection functions
842
Operation mode
Freq> + df/dt
Freq< OR df/dt
Freq> OR df/dt
Description
A consecutive operation is enabled between the
protection methods. When the measured
frequency exceeds the set value of the
Freq> setting, the frequency gradient protection is
enabled. After the frequency exceeds the set
value, the frequency gradient is compared to the
Start value df/dt setting. When the
set value of 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
Operate Tm df/dt setting, the
value set by the
OPERATE and OPR_FRG outputs are activated. If
the frequency gradient restores before the module
operates, the reset timer is activated. If the timer
reaches the value set by the
setting, 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.
A parallel operation between the protection
methods is enabled. The START 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 STR_UFRQ and STR_FRG outputs.
The shortest operate delay time from the set
Operate Tm Freq or Operate Tm df/dt is dominant
regarding the OPERATE output. The time
characteristic is according to DT. The
characteristic that activates the OPERATE output
can be seen from the OPR_UFRQ or OPR_FRG
output. If the frequency gradient restores before
the module operates, the reset timer is activated. If
the timer reaches the value set by the
Tm df/dt setting, the operate timer resets and the
STR_FRG output is deactivated. If the frequency
restores before the module operates, the reset
timer is activated. If the timer reaches the value set
Reset delay Tm Freq setting, the operate
by the
timer resets and the STR_UFRQ output is
deactivated.
A parallel operation between the protection
methods is enabled. The START output is
activated when either of the measured values of
the protection module exceeds its set value. A
detailed information from the active module is
available at the STR_OFRQ and STR_FRG outputs.
The shortest operate delay time from the set
Operate Tm Freq or Operate Tm df/dt is dominant
regarding the OPERATE output. The time
characteristic is according to DT. The
characteristic that activates the OPERATE output
can be seen from the OPR_OFRQ or OPR_FRG
output. If the frequency gradient restores before
the module operates, the reset timer is activated. If
the timer reaches the value set by the
Tm df/dt setting, the operate timer resets and the
STR_FRG output is deactivated. If the frequency
restores before the module operates, the reset
timer is activated. If the timer reaches the value set
Reset delay Tm Freq setting, the operate
by the
timer resets and the STR_UFRQ output is
deactivated.
1MRS759142 C
Start value
Reset delay Tm df/dt
Reset delay
Reset delay
REX640
Technical Manual