VAMP 259 - Page 106

2.15 Undervoltage protection U< (27)
2 Protection functions
Technical description
106
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VM259.EN007
Figure shows an example of low voltage self blocking.
A
The maximum of the three line-to-line voltages U
LLmax
is below the block limit. This is not regarded as an
under voltage situation.
B
The voltage U
LLmin
is above the block limit but below
the pick-up level. This is an undervoltage situation.
C
Voltage is OK, because it is above the pick-up limit.
D
This is an under voltage situation.
E
Voltage is OK.
F
This is an under voltage situation.
G
The voltage U
LLmin
is under block limit and this is not
regarded as an under voltage situation.
H
This is an under voltage situation.
I
Voltage is OK.
J
Same as G
K
Voltage is OK.
Figure 2.15-1 Under voltage state and block limit.
Three independent stages
There are three separately adjustable stages: U<, U<< and
U<<<. All these stages can be configured for definite time (DT)
operation characteristic.