Operation mode
Description
Freq> + df/dt A consecutive operation is enabled between the
protection methods. When the measured
frequency exceeds the set value 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
before the module operates, the reset timer is
activated. 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_OFRQ output
is not active when this operation mode is used.
Freq< OR df/dt 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
Reset
delay 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 by the
Reset delay Tm Freq
setting, the operate timer resets and the
STR_UFRQ output is deactivated.
Table continues on next page
Section 4 1YHT530004D05 D
Protection functions
498 615 series
Technical Manual
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