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Functions
3.4 51 Time-Delayed Overcurrent – Phase
The reset parameter is used to define whether the element pickup resets to 0 instantaneously when the
current falls below the setting or a reset curve characteristic or fixed DTL is applied. This operation is signifi-
cant during intermittent faults where an induction disc device would be partially rotated when the fault
current is reapplied.
Parameter Value
IEC/ANSI Decay
00 s
01 s – 60 s
Gn 51-n Inrush Action
Default Setting: Off
High levels of inrush currents into reactive components, for example transformers; when they are switched in
can result in operation of overcurrent elements. The inrush current can be detected by the 81HBL2 element.
This parameter can be configured to inhibit the overcurrent element automatically.
Parameter Value
Off
Inhibit
Settings Example
The 51-n characteristic element provides a number of time/current operate characteristics. The element can be
defined as either an Inverse Definite Minimum Time Lag (IDMTL) or Definite Time Lag (DTL) characteristic. If
an IDMTL characteristic is required, then IEC and ANSI/IEEE curves are supported. IDMTL characteristics are
defined as inverse because their tripping times are inversely proportional to the fault current being measured.
This makes them particularly suitable to grading studies where it is important that only the relay/relays closest
to the fault operate. Differentiation can be achieved with minimized operating times. For more details, refer to
5.3 Time-Delayed Overcurrent (51/51N)
Settings Menu
CONFIGURATION > FUNCTION CONFIG
Parameter
Gn Phase O/C
CONFIGURATION > CURRENT PROT'N > PHASE O/C > 51-n
Parameter
Gn 51-n Element
48
Description
This selection applies a resetting curve to the element pickup to provide
emulation of an induction disc device. The standard IEC curve is applied if
the operating Char is an IEC Characteristic and the ANSI reset curve is
applied for an ANSI operating Char. Select this setting if the device is coor-
dinated with electromechanical devices or other devices which perform a
disc emulation reset.
Use this setting for instantaneous reset of the element. When the current
falls below the setting, the pickup resets completely instantaneously and
subsequent increase in current above the setting restarts the operation
delay from 0.
The percentage operated state is retained when the current falls below the
setting for a period of the set delay. A subsequent increase in current to
above the setting within the set delay allows operation to resume from the
partially operated state instead of 0.
Description
The overcurrent element is not affected by operation of the 81HBL2
element.
The overcurrent element is inhibited by operation of the 81HBL2 element
and automatically released when the 81HBL2 element resets.
.
Setting Options
Disabled
Enabled
Setting Options
Disabled
Enabled
Settings
Default
Gn1
Disabled
–
Settings
Default
Gn1
Disabled
–
C53000-G7040-C103-1, Edition 10.2022
Gn2
–
Gn2
–
Reyrolle, 7SR46 Device, Manual
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