ABB Relion 670 Series Applications Manual page 219

1MRK 511 401-UEN Rev. K
Section 9
9.1 Two step undervoltage protection UV2PTUV
9.1.1 Identification
Function description
Two step undervoltage protection
9.1.2 Application
Two-step undervoltage protection function (UV2PTUV) is applied to power system elements,
such as generators, transformers, motors and power lines in order to detect low voltage
conditions. It is used as a supervision and fault detection function for other protection
functions as well, to increase the security of a complete protection system. Low voltage
conditions are caused by abnormal operation or faults in the power system, such as:
• Malfunctioning of a voltage regulator or wrong settings under manual control
(symmetrical voltage decrease)
• Overload (symmetrical voltage decrease)
• Short circuits, often as phase-to-earth faults (unsymmetrical voltage decrease)
UV2PTUV is used in combination with overcurrent protections, either as restraint or in logic
"and gates" of the trip signals issued by the two functions. It can also be used to:
• Detect no voltage conditions, for example, before the energization of a HV line or for
automatic breaker trip in case of a blackout
• Initiate voltage correction measures, like insertion of shunt capacitor banks to
compensate for reactive load and thereby increasing the voltage
• Disconnect apparatuses, like electric motors, which will be damaged when subject to
service under low voltage conditions.
The function has a high measuring accuracy and a settable hysteresis to allow applications to
control reactive load.
In many cases, UV2PTUV is a useful function in circuits for local or remote automation
processes in the power system.
9.1.3 Setting guidelines
All the voltage conditions in the system where UV2PTUV performs its functions should be
considered. The same also applies to the associated equipment, its voltage and time
characteristic.
There is a very wide application area where general undervoltage functions are used. All
voltage-related settings are made as a percentage of the global base value
Bay control REC670
Application manual
Voltage protection
IEC 61850
identification
UV2PTUV
© Copyright 2017 Hitachi Power Grids. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
27
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V2 EN-US SYMBOL-R-2U-GREATER-THAN
Section 9
Voltage protection
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