1MAC309294-MB F Section 4
Protection functions
RER620 217
Technical Manual
4.4.1.2 Function block
Figure 99: Function block
4.4.1.3 Functionality
The frequency protection functions (81O/81U, 81R) are used to protect network
components against abnormal frequency conditions.
The function provides basic overfrequency, underfrequency and frequency rate of change
protection. Additionally, it is possible to use combined criteria to achieve even more
sophisticated protection schemes for the system.
The function contains a blocking functionality. It is possible to block function outputs,
timer or the function itself, if desired.
4.4.1.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are “On” and “Off”.
The operation of the frequency protection function can be described using a module
diagram. All the modules in the diagram are explained in the next sections.
f
df/dt
81O/81U, 81R
TRIP
TRIP_UFRQ
TRIP_OFRQ
TRIP_FRG
PICKUP
PICKUP_UFRQ
PICKUP_OFRQ
PICKUP_FRG
BLOCK
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