Section 9
Frequency protection
About this chapter
This chapter describes the frequency protection functions. The way the functions work,
their setting parameters, function blocks, input and output signals and technical data
are included for each function.
9.1
Underfrequency protection SAPTUF (81)
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Underfrequency protection
SAPTUF
f <
SYMBOL-P V1 EN
81
9.1.1
Introduction
Underfrequency occurs as a result of a lack of generation in the network.
Underfrequency protection SAPTUF (81) is used for load shedding systems, remedial
action schemes, gas turbine startup and so on.
SAPTUF (81) is also provided with undervoltage blocking.
The operation is based on positive sequence voltage measurement and requires two phase-
phase or three phase-neutral voltages to be connected. For information about how to
connect analog inputs, refer to
Application manual/IED application/Analog inputs/
Setting guidelines
9.1.2
Principle of operation
Underfrequency protection SAPTUF (81) is used to detect low power system
frequency. SAPTUF (81) can either have a definite time delay or a voltage magnitude
dependent time delay. If the voltage magnitude dependent time delay is applied, the
time delay will be longer if the voltage is higher, and the delay will be shorter if the
1MRK505222-UUS C
Section 9
Frequency protection
551
Technical reference manual
Summary of Contents for Relion 670 series
Page 1: ...Relion 670 series Line differential protection RED670 ANSI Technical reference manual...
Page 2: ......
Page 40: ...34...
Page 50: ...44...
Page 60: ...54...
Page 126: ...120...
Page 384: ...378...
Page 496: ...490...
Page 556: ...550...
Page 602: ...596...
Page 620: ...614...
Page 794: ...788...
Page 864: ...858...
Page 988: ...982...
Page 998: ...992...
Page 1084: ...1078...
Page 1164: ...1158...
Page 1168: ...1162...
Page 1220: ...1214...
Page 1230: ...1224...
Page 1231: ...1225...