Siemens Reyrolle 7SR5 Manual page 259

Parameter: Reset
•
Default setting: 0 s
The Reset parameter is used to define whether the element pickup resets to 0 instantaneously when the
current falls below 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 Decaying
0 s
1 s to 60 s
Parameter: VTS Action
•
Default setting: Off
Voltage transformer failure can affect the directional decision and introduce an error. This setting selects
if operation of the 60VTS Voltage Transformer Supervision element automatically affects the
operation of the element.
Parameter Value
Off
Inhibit
Non-Dir
NOTE
i i
During a VT failure the device may assess the direction incorrectly and the element may operate for faults
in the non-operate direction or not operate for faults in the operate direction.
Parameter: 81HB2 Inhibit
•
Default setting: No
High levels of inrush currents into reactive components such as transformers when they are switched in
can result in operation of overcurrent elements. The inrush current can be detected by the 81HBL2
element. This can be configured to inhibit the overcurrent element automatically.
Parameter Value
No
Yes
Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019
Description
This selection applies a resetting curve to the element pickup to provide emula-
tion 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 oper-
ating Char. Select this setting if the device is coordinated 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 setting the pickup will instantaneously reset completely and subsequent
increase in current above setting will restart the operation delay from 0.
The percentage operated state is retained when the current falls below setting for
a period of the set delay. Subsequent increase in current to above setting within
the set delay will allow operation to resume from the partially operated state
instead of 0.
Description
The function element operates with no consideration of the 60VTS element
output status.
When a VT failure is determined by the 60VTS function operation of the function
element is inhibited. Clearance of a system fault will then rely on other elements
or devices.
When a VT failure is determined by the 60VTS function the 51 element is
switched to non-directional operation – this does not require VT inputs. The
element will operate for overcurrent regardless of current direction.
Description
The element is not inhibited 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.
Protection and Automation Functions
5.16 51N Time-Delayed Earth Fault – Calculated
259