Section 10 Voltage protection
10.1 Two step undervoltage protection UV2PTUV (27)
10.1.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Two step undervoltage protection UV2PTUV
SYMBOL-R-2U-GREATER-THAN
V2 EN
27
10.1.2 Application
Two-step undervoltage protection function (UV2PTUV ,27) 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-ground faults (unsymmetrical voltage decrease)
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. 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.
1MRK 506 369-UUS - Section 10
Voltage protection
Line distance protection REL670 2.2 ANSI 567
Application manual
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