ABB Relion Applications Manual page 44

Section 3
REU611 standardized configuration
38
FREQUENCY PROTECTION INDICATION
FRPFRQ1
f>/f<,df/dt (1)
81(1)
3U OPERATE
BLOCK START
FRPFRQ2
f>/f<,df/dt (2)
81(2)
3U OPERATE
BLOCK START
GUID-8E6B38BF-E8C6-4346-9EA4-F6A3DB231343 V1 EN
Figure 19: Frequency protection
The selectable underfrequency or overfrequency protection FRPFRQ prevents
damage to network components under unwanted frequency conditions. The function
also contains a selectable rate of change of the frequency (gradient) protection to
detect an increase or decrease in the rapid changing power system frequency at an
early stage. This can be used as an early indication of a disturbance in the system.
The operate signals of these frequency protections are connected to the master trip and
to alarm LED 5.
OSWGAPC16
IN_12
OUT
OR
1MRS758335 B
SELGAPC4
IN_17 OUT_5
LED 5
REU611
Application Manual