ABB ret650, Technical Manual

Page: 240 / 670

When the measured frequency returns to the level corresponding to the setting
RestoreFreq , a 100ms pulse is given on the output RESTORE after a settable time
delay ( tRestore ).
10.1.7.3 Blocking
It is possible to block underfrequency protection SAPTUF completely, by binary
input signal:
BLOCK: blocks all outputs
If the measured voltage level decreases below the setting of MinValFreqMeas in the
preprocessing function both the START and the TRIP outputs are blocked.
10.1.7.4 Design
The design of underfrequency protection SAPTUF is schematically described in
figure
103 .
Figure 104: Simplified logic diagram for SAPTUF
10.1.8 Technical data
Table 158: SAPTUF Technical data
Function Range or value Accuracy
Operate value, start function (35.00-75.00) Hz ± 2.0 mHz at
symmetrical three-
phase voltage
Operate value, restore
frequency
(45 - 65) Hz ± 2.0 mHz
Reset ratio <1.001 -
Operate time, start function At 50 Hz: 200 ms typically at f
set
+0.5 Hz to f
set
-0.5 Hz
At 60 Hz: 170 ms typically at f
set
+0.5 Hz to f
set
-0.5 Hz
-
Reset time, start function At 50 Hz: 60 ms typically at f
set
-0.5 Hz to f
set
+0.5 Hz
At 60 Hz: 50 ms typically at f
set
-0.5 Hz to f
set
+0.5 Hz
-
Operate time delay (0.000-60.000)s <250 ms
Restore time delay (0.000-60.000)s <150 ms
10.2 Overfrequency protection SAPTOF
Section 10
1MRK 504 135-UEN A
Frequency protection
234
Technical manual