Function Block; Functionality; Operation Principle - ABB RELION 620 Series Technical Manual

1MAC504801-IB E
4.3.1.2
4.3.1.3
4.3.1.4
620 series ANSI
Technical Manual

Function block

81
F TRIP
dF/dt TRIP_UFRQ
BLOCK TRIP_OFRQ
TRIP_FRG
PICKUP
PICKUP_UFRQ
PICKUP_OFRQ
PICKUP_FRG
GUID-8B7AA565-288B-42EA-961B-A9F7B93E47F0-ANSI V3 EN
Figure 144: Function block

Functionality

The frequency protection 81 is 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.

Operation principle

The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
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.
GUID-9BF0484B-1BC9-4C44-B64A-A2D6AB246916-ANSI V1 EN
Figure 145: Functional module diagram
Section 4
Protection functions
319