Hitachi Relion 670 Series Applications Manual page 189

1MRK506375-UEN Rev. N
Section 9
9.1 Two step undervoltage protection U2RWPTUV
9.1.1 Function revision history
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revision
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9.1.2 Identification
Function description
Undervoltage protection, two steps
9.1.3 Application
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).
Railway application RER670
Application manual
Voltage protection
Product History
revision
2.2.1 -
2.2.1 -
2.2.2 -
2.2.3 -
2.2.3 -
2.2.4 -
2.2.4 -
2.2.5 -
2.2.6 -
2.2.6 Programmable inverse curve for operating characteristic is added.
IEC 61850
identification
U2RWPTUV
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GUID-314D4095-0121-4FFA-BB88-7F861232DE8B v2
GUID-88CAE956-8939-425F-BD02-60AB03BE8D38 v2
IEC 60617 ANSI/IEEE C37.2
identification device number
27
2(2U<)
IEC15000109 V1 EN-US
Section 9
Voltage protection
M16876-1 v8
M13790-3 v8
183