2.11 Underexcitation (Loss-of-Field) Protection (ANSI 40)
83
7UM61 Manual
C53000-G1176-C127-3
Delay Times If the static limit curve consisting of the characteristics 1 and 2 is exceeded, the voltage
regulator must first have the opportunity of increasing the excitation. For this reason,
a warning message due to this criterion is ”long-time" delayed (at least 10 s for 3004
T CHAR. 1 and 3007 T CHAR. 2).
However if an external excitation monitoring signals the failure of an excitation voltage
to the device via a binary input, a switch-off can be performed with a short time delay.
Table 2-4 Setting the Underexcitation Protection
Note: If very short time delays are selected, dynamic balancing procedures may
cause unwanted operations. For this reason, it is recommended to set time values of
0.05 s or higher.
2.11.3 Settings
Addresses which have an appended "A" can only be changed with DIGSI, under Ad-
ditional Settings.
Characteristic 1 and 2 static stability undelayed Annunciation:
Exc < Anr
Characteristic 1 and 2 static stability long-time delayed
T CHAR. 1 = T CHAR. 2 ≈
10 s
Trippings
Err<1 TRIP / Err<2 TRIP
Characteristic 1 and 2 Excitation
Voltage Failure
short–time delayed
T SHRT Uex< ≈ 1.5 s
Tripping
Err< UPU < TRIP
Characteristic 3 dynamic stability short–time delayed
T CHAR 3 ≈ 0.5 s
Tripping
Exc<3 TRIP
Addr. Parameter Setting Options Default Setting Comments
3001 UNDEREXCIT. OFF
ON
Block relay
OFF Underexcitation Protection
3002 1/xd CHAR. 1 0.25 .. 3.00 0.41 Conductance Intersect Character-
istic 1
3003 ANGLE 1 50 .. 120 ° 80 ° Inclination Angle of Characteristic
1
3004 T CHAR. 1 0.00 .. 60.00 sec; ∞ 10.00 sec Characteristic 1 Time Delay
3005 1/xd CHAR. 2 0.25 .. 3.00 0.36 Conductance Intersect Character-
istic 2
3006 ANGLE 2 50 .. 120 ° 90 ° Inclination Angle of Characteristic
2
3007 T CHAR. 2 0.00 .. 60.00 sec; ∞ 10.00 sec Characteristic 2 Time Delay
3008 1/xd CHAR. 3 0.25 .. 3.00 1.10 Conductance Intersect Character-
istic 3
3009 ANGLE 3 50 .. 120 ° 90 ° Inclination Angle of Characteristic
3
3010 T CHAR 3 0.00 .. 60.00 sec; ∞ 0.30 sec Characteristic 3 Time Delay
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