ABB REU615 Applications Manual page 43

1MRS757054 A
REU615
Application Manual
The function contains a selectable rate of change of the frequency (gradient)
protection to detect an increase or decrease in the fast power system frequency at
an early stage. This can be used as an early indication of a disturbance in the
system. The operation signal is connected to alarm LED 5.
GUID-3B69C572-5221-4320-850C-DD1DB0933037 V1 EN
Figure 16: Load shedding and restoration
Five load shedding and restoration stages are offered in the standard configuration.
The load shedding and restoration function (LSHDPFRQ) is capable of shedding
load based on underfrequency and the rate of change of the frequency. The load
that is shed during the frequency disturbance can be restored once the frequency is
stabilized to the normal level. Also manual restore commands can be given via
binary inputs.
REU615 standard configurations
Section 3
37