Settings Of The Underexcitation (Loss-Of-Field) Protection - Siemens Siprotec 7UM62 Manual

Excitation Voltage
Request

2.14.2.1 Settings of the Underexcitation (Loss-of-Field) Protection

Addr. Setting Title
3001 UNDEREXCIT.
3011 T SHRT Uex<
7UM62 Manual
C53000-G1176-C149-3
This feature is set at address 3011 T SHRT Uex<. The following messages and trip
commands are typically assigned:
Table 2-6 Setting the Underexcitation Protection
Characteristic 1 and 2 static
stability
Characteristic 1 and 2 static
stability
Characteristic 1 and 2
excitation voltage failure
Characteristic 3
dynamic stability
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.
The excitation voltage monitoring feature is set to approx. 50 % of the no-load excita-
tion voltage. If the generator is used for phase-shifting, an even lower threshold must
be chosen, depending on the application in had. It should also be noted that normally
a voltage divider is connected between the device and the excitation voltage.
SettingxU Exc <
where U No-load excitation voltage,
Exc
k Transformation ratio of voltage divider
VD
Example:
U
Exc N
U
Exc 0
k
VD
Setting U Exc <
Setting Options
OFF
ON
Block relay for trip com-
mands
0.00..60.00 sec; ∞
Underexcitation (Loss-of-Field) Protection (ANSI 40)
not delayed
long-time delayed
T CHAR. 1 = T CHAR. 2
≈ 10 s
short–time delayed
T SHRT Uex< ≈ 1.5 s
short–time delayed
T CHAR 3 ≈ 0.5 s
U
Exc 0
≈ ⋅ [ ]
0.50 --------------- - V
k
U
= 110 V
= 40 V
= 10: 1
40 V
≈ ⋅
= 2.0 V (address 3013)
----------- -
0.50
10
Default Setting
OFF
0.50 sec
Annunciation:
Err < PU
Trip
Exc<1 TRIP / Exc<2 TRIP
Trip
Exc< Uexc < TRIP
Trip
Exc<3 TRIP
Comments
Underexcitation Protection
T-Short Time Delay (Char. &
Uexc<)
113