Section 9 Voltage Protection - ABB RELION 670 Series Applications Manual

1MRK 511 364-UUS A
Section 9
9.1 Two step undervoltage protection UV2PTUV (27)
9.1.1 Identification
Function description
Two step undervoltage protection
9.1.2 Application
Two-step undervoltage protection function (UV2PTUV ,27) is applicable in all situations, where
reliable detection of low phase voltages is necessary. It is used also as a supervision and fault
detection function for other protection functions, to increase the security of a complete
protection system.
UV2PTUV (27) is applied to power system elements, such as generators, transformers, motors and
power lines in order to detect low voltage conditions. Low voltage conditions are caused by
abnormal operation or fault in the power system. UV2PTUV (27) 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. UV2PTUV (27) is
also used to initiate voltage correction measures, like insertion of shunt capacitor banks to
compensate for reactive load and thereby increasing the voltage. The function has a high
measuring accuracy and setting hysteresis to allow applications to control reactive load.
UV2PTUV (27) is used to disconnect apparatuses, like electric motors, which will be damaged when
subject to service under low voltage conditions. UV2PTUV (27) 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-ground faults (unsymmetrical voltage decrease).
UV2PTUV (27) prevents sensitive equipment from running under conditions that could cause their
overheating and thus shorten their life time expectancy. In many cases, it is a useful function in
circuits for local or remote automation processes in the power system.
Application manual
Voltage protection
IEC 61850
identification
UV2PTUV
IEC 60617 ANSI/IEEE C37.2
identification device number
27
3U<
V2 EN-US SYMBOL-R-2U-GREATER-THAN
Section 9
Voltage protection
IP14544-1 v3
M16876-1 v6
M13790-3 v7
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