Measurement Principle; Time Delay - ABB REG650 Technical Manual

1MRK 502 048-UEN A
10.1.7.1
10.1.7.2
Technical manual
voltage is lower than the set blocking voltage in the preprocessing function, the
function is blocked and no START or TRIP signal is issued.

Measurement principle

The frequency measuring element continuously measures the frequency of the
positive sequence voltage and compares it to the setting StartFrequency. The
frequency signal is filtered to avoid transients due to switchings and faults in the
power system. If the voltage magnitude decreases below the setting MinValFreqMeas
in the SMAI preprocessing function, which is described in the Basic IED Functions
chapter and is set as a percentage of a global base voltage parameter, SAPTUF gets
blocked, and the output BLKDMAGN is issued. All voltage settings are made in
percent of the setting of the global parameter UBase.
To avoid oscillations of the output START signal, a hysteresis has been included.
BLOCK
freqNotValid
Frequency Comparator
f < StartFrequency
Comparator
f > RestoreFreq
IEC09000034 V1 EN
Figure 149: Simplified logic diagram for SAPTUF

Time delay

The time delay for SAPTUF is a settable definite time delay, specified by the setting
tDelay.
Trip signal issuing requires that the under frequency condition continues for at least
the user set time delay. If the START ceases during the delay time, and is not fulfilled
again within a defined reset time, the START output is reset.
Frequency protection
BLOCK
OR
Start
&
START
DefiniteTimeDelay
Trip
Output
TimeDlyOperate
Logic
TRIP
TimeDlyRestore
Section 10
BLKDMAGN
START
TRIP
100 ms
RESTORE
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