ABB REO 517, Applications Manual, Page: 152 / 440

142
Inverse time delayed undervoltage
protection (TUV2)
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The parameters for the inverse time delayed undervoltage protection function are set via
the local HMI or PST (Parameter Setting Tool). Refer to the Technical reference man-
ual for setting parameters and path in local HMI.
All the voltage conditions in the system where the undervoltage protection performs its
functions should be considered. The same also applies to the associated equipment, its
voltage and time characteristic.
The undervoltage functions operate voltage is normally set to approximately. 10% low-
er than the lowest phase-to-neutral voltage with normal operations (safety margin de-
pending on the inaccuracy of the instrument transformers, calculation methods and the
terminal’s measuring element). The delay must be adapted to the operate time of other
protection functions affected by faults, that give rise to a voltage drop in the network,
for example, earth faults and short-circuit protection.
en02000536.v sd
TUV2-BLOCK
TUV2-VTSU
>1
UL1
UL2
>1
&
t
t=500 ms
TUV2-TRIP
t=
k
1-
UL1
U<Inv
0.5
0.5
t=
k
1-
UL2
U<Inv