Settings Menu - Siemens Reyrolle 7SR5 Manual

Protection and Automation Functions
5.16 51N Time-Delayed Earth Fault – Calculated
Parameter: 79 Delayed Inhibit
•
Default setting: No
The autoreclose scheme can be designed such that only instantaneous elements are used for the first
trip(s) of the sequence before reverting to time graded protection. This setting allows the delayed
element to be inhibited during the delayed autoreclose shots and should be left at the default setting of
Off unless this is required.
Note that function elements are assigned as Delayed Trips in the 79 > 79PF menu.
Parameter Value
No
Yes
Settings Example
There should be little or no current flowing to earth in a healthy system so earth fault relays can be given far
lower pickup levels than relays which detect excess current above load current in each phase conductor. Earth
fault relays are important where the fault path to earth is a high-resistance one (such as in highly arid areas) or
where the system uses high values of earthing resistor/reactance as any earth fault current that flows in the
phase conductors will be limited.

Settings Menu

5.16.5
Configuration > Function Config
Parameter
51N Earth Fault
Functions > Protection > 51N > Gn 51N-n
Parameter
Element
10
Dir. Control
Setting
Char
10 Applies only to devices with VT inputs.
260
Description
The element is not inhibited by the autoreclose sequence design.
The element will be inhibited during any autoreclose shot which is designated as
delayed. Incorrect configuration can result in no protection being enabled.
Setting Options
Enabled
Disabled
Setting Options
Enabled
Disabled
Non-Dir
Forward
Reverse
0.05 to 2.5 ⋅ I , Δ 0.05
rated
I
rated
DTL
IEC-NI
IEC-VI
IEC-EI
IEC-LTI
ANSI-EI
ANSI-MI
ANSI-VI
Settings
Default Gn1 Gn2
Disabled
Settings
Default Gn1 Gn2
Disabled
Non-Dir
0.5 ⋅
I
rated
IEC-NI
Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019
Gn3 Gn4
Gn3 Gn4