ABB RELION 650 SERIES, Technical Manual

Page: 309 / 942

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-US
Figure 151: 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.
9.1.6.4 Blocking
M13354-50 v7
It is possible to block underfrequency protection SAPTUF partially or completely,
by binary input signals or by parameter settings, where:
BLOCK: blocks the START, TRIP and
RESTORE outputs
BLKTRIP: blocks the TRIP output
BLKREST: blocks the RESTORE output
If the measured voltage level decreases below the setting of IntBlockLevel , both the
START and the TRIP outputs are blocked.
9.1.6.5 Design
M13354-63 v10
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
RestoreFreq , the RESTORE output is issued after the time delay tRestore . The
design of underfrequency protection SAPTUF is schematically described in
figure
152 .
1MRK 506 382-UEN A
Section 9
Frequency protection
Line distance protection REL650 2.2 IEC 303
Technical manual