Application and Setting Notes
Parameter:
Element
•
Default setting:
Disabled
This setting is used to allow the element to be switched on and off if it is not required. A separate setting
is provided for each element. These setting can be used to select the number of elements required.
Parameter Value
Description
Disabled
This element is switched out and is not available.
Enabled
The element is available for use and can be parameterized.
Parameter:
Dir. Control
•
Default setting:
Non-Dir
This setting is used to define whether the element will operate for earth faults detected in the
Forward
or
Reverse
direction based on the 67N directional element decision or for any earth fault regardless of
the 67N direction. This allows the earth fault protection to have different current and time settings for
forward, reverse and non-directional faults by using three 67N function elements.
This parameter is not provided in devices that do not have voltage inputs or for current inputs that are
not polarized by the voltage inputs.
Parameter Value
Description
Non-Dir
Select this setting if the element is to operate regardless of the current direction
or presence of voltage.
Forward
Select this setting if the element is to operate only in a forward direction.
Reverse
Select this setting if the element is to operate only in a reverse direction.
Parameter:
Setting
•
Default setting: 0.5 x I
n
(0.5 ⋅ I
rated
)
This setting defines the operating current threshold of the element. The calculated earth current must
exceed this setting by a factor of 1.05 for pickup of the element. The operation timing will then be
dependent on the selected characteristic for the element setting. The element pickup will reset when the
current is reduced by a factor of 0.97 the setting, and the reset characteristic will be applied. This factor is
always applied for 51N elements including when the
Char
is selected as DTL.
This setting should be set to suit the individual application.
Parameter:
Char
•
Default setting:
IEC NI
(IEC normal inverse)
This setting defines the characteristic of the inverse curve. Standard ANSI and IEC curves are provided as
standard. The characteristic curves and associated formulas are shown in
Custom (user defined) curves can be configured in Reydisp Manager and added to the device configura-
tion. The custom curve will appear as an additional option in the
Char
setting list using the name that is
entered in Reydisp Manager for all elements for which the curve is applicable.
The characteristic can also be set as DTL, see
Delay
,
The characteristic should be set to suit the individual application.
5.16.4
Protection and Automation Functions
5.16 51N Time-Delayed Earth Fault – Calculated
Reyrolle 7SR5, Transformer Protection Device, Device Manual
257
C53000-G7040-C015-1, Edition 11.2019