ABB REO 517, Applications Manual

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138
Time delayed undervoltage protection
(TUV) for two sections (TUV1)
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The undervoltage protection, TUV is intended for single- and two-phase systems and is
applicable in all situations, where reliable detection of low phase voltages is necessary.
The protection prevents sensitive elements from running under conditions that could
cause overheating and thus shorten their life expectancy below the economical limits.
In many cases, it is a useful tool in circuits for local or remote automation processes in
the power system.
The undervoltage function TUV1 is intended to be used as a supplement to the normal
undervoltage function TUV in single-phase systems in situations where there is a need
for two totally separated functions (settings, in- and outputs) for example for protection
of two buses that can be separated. In those applications TUV uses input U1 and TUV1
uses input U2.
The undervoltage protection, TUV1 is intended for single-phase systems and is appli-
cable in all situations, where reliable detection of low phase voltages is necessary.
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The voltage measuring elements within one of the built-in digital signal processors con-
tinuously measure the phase-to-neutral voltages in all phases. Recursive Fourier filter
filters the input voltage signals and a separate trip counter prevents high overreaching
or underreaching of the measuring elements. If the voltage falls below the set value for
a longer period than the set delay the protection gives a trip command.
The undervoltage protection, TUV, is blocked if the input signal TUV-BLOCK is acti-
vated. The trip output is blocked if the input signal TUV-BLKTR is activated.
The signal TUV-VTZU, which may be connected to the fuse-failure supervision func-
tion, prevents unwanted operation.