ABB RELION RER670, Applications Manual

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Section 9 Voltage protection
9.1 Two step undervoltage protection U2RWPTUV
GUID-314D4095-0121-4FFA-BB88-7F861232DE8B v1
9.1.1 Identification
M16876-1 v7
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Undervoltage protection, two steps U2RWPTUV
2(2U<)
IEC15000109 V1 EN-US
27
9.1.2 Application
M13790-3 v8
Two-step undervoltage protection function (U2RWPTUV) is applicable in all
situations, where reliable detection of low phase voltages is necessary. It is also
used as a supervision and fault detection function for other protection functions to
increase the security of a complete protection system.
U2RWPTUV is applied to transformers and power lines in order to detect low
voltage conditions. Low voltage conditions are caused by abnormal operation or
fault in the power system. U2RWPTUV is used in combination with overcurrent
protections, either as restraint or in logic "and gates" of the trip signals issued by
the two functions. Other applications are the detection of "no voltage" condition,
for example, before the energization of a HV line or for automatic breaker trip in
case of a blackout.
U2RWPTUV is used to disconnect apparatuses which will be damaged when
subject to service under low voltage conditions. U2RWPTUV deals with low
voltage conditions at power system frequency, which can be caused by the
following reasons:
1. Malfunctioning of a voltage regulator or wrong settings under manual control
(symmetrical voltage decrease).
2. Overload (symmetrical voltage decrease).
3. Short circuits, often as phase-to-earth faults (unsymmetrical voltage decrease).
U2RWPTUV prevents sensitive equipment from running under conditions that
could cause overheating and thus shorten their life time expectancy. In many cases,
1MRK 506 375-UEN A
Section 9
Voltage protection
Railway application RER670 2.2 IEC 195
Application manual