VAMP 52 - Page 87

Technical description 2 Protection functions 2.18 Single-phase undervolta
g
e
protection U<
(
27
)
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The undervoltage function can be blocked with an external
digital signal for example if the secondary voltage of the
measuring transformers disappears (e.g. fuse failure). The
undervoltage function can also be blocked with an internal
blocking signal, which is defined during the parameterisation.
Further, the function can be blocked with a separate NoCmp
setting. With this setting, all the protection stages are blocked
even when the actual values for all the phases fall below the set
value.
&
t
&
&
>
ts
tr
MAX
1vup
Setting
U<s
Delay Enable
events
Start
Trip
Event
register
Um1
Blocking
Event
register
NoCmp
Hysteresis
Release
delay
Figure 2.18-1 Block diagram of the single-phase undervoltage stages U<,
U<< and U<<<
Setting parameters of single-phase undervoltage stages U<,
U<<, U<<< (27):
Parameter Value Unit Default Description
U<, U<<,
U<<<
20 … 120 %Un 80 (U<)
70 (U<<, U<<<)
Undervoltage
setting
t<, t<<,
t<<<
0.08 …
300.00
0.06 …
300.00
s 20.00 (U<)
2.00 (U<<,
U<<<)
Definite
operation time
NoCmp 0 … 80 %Un 10
Self-blocking
value
ReleaseDly 0.06 … 300.0 s -
Release delay
(only U<)
Hysteresis 0.1 … 20.0 % -
Deadband (only
U<)
S_On
Enabled;
Disabled
- Enabled Start on event
S_Off
Enabled;
Disabled
- Enabled Start off event
T_On
Enabled;
Disabled
- Enabled Trip on event
T_Off
Enabled;
Disabled
- Enabled Trip off event