UMin
= 90%
UNom
= 100%
tMax
= 1.0 s
tMin
= 0.0 s
Exponent
= 0, 1, 2, 3 and 4
90
95
100
0
0.5
1
en05000075.vsd
T
im
eD
ly
O
pe
ra
te
[s
]
U [% of UBase]
Exponenent
0
1
2
3
4
IEC05000075 V1 EN
Figure 263:
Voltage dependent inverse time characteristics for underfrequency
protection SAPTUF. The time delay to operate is plotted as a function
of the measured voltage, for the Exponent = 0, 1, 2, 3, 4 respectively.
10.1.7.4
Blocking
It is possible to block underfrequency protection SAPTUF partially or completely, by
binary input signals or by parameter settings, where:
BLOCK:
blocks all outputs
BLKTRIP:
blocks the TRIP output
BLKREST:
blocks the RESTORE output
If the measured voltage level decreases below the setting of
MinValFreqMeas
in the
preprocessing function both the START and the TRIP outputs are blocked.
10.1.7.5
Design
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. The time
integrator can operate either due to a definite delay time or to the special voltage
dependent delay time. When the frequency has returned back to the setting of
1MRK502052-UEN B
Section 10
Frequency protection
547
Technical manual
Summary of Contents for Relion REG670
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