ABB RELION REX640 Technical Manual page 855

1MRS759142 C
REX640
Technical Manual
reset timer is activated. If the reset timer reaches the value of the Reset delay time
setting, the timer resets and the ST_FRG output is deactivated.
Load-shedding control
The way of load-shedding, that is, whether to operate based on underfrequency or high
df/dt or both, is defined with the Load shed mode user setting. The valid operation
modes for the Load shed mode settings are "Freq<", "Freq< AND df/dt" and "Freq<
OR df/dt".
Once the selected operation mode conditions are satisfied, the START and OPERATE
output signals are activated.
When the START output is active, the percentage of the elapsed delay time can be
monitored through START_DUR which is available as monitored data.
Section 4
Protection functions
849