Section 9 Voltage protection
9.1 Two step undervoltage protection UV2PTUV
IP14544-1 v3
9.1.1 Identification
M16876-1 v7
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Two step undervoltage protection UV2PTUV
SYMBOL-R-2U-GREATER-THANV2 EN-US
27
9.1.2 Application
M13790-3 v8
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.
1MRK 505 393-UEN B Section 9
Voltage protection
Line differential protection RED650 2.2 IEC 189
Application manual
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