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 Description
No The element is not inhibited by the autoreclose sequence design.
Yes The element will be inhibited during any autoreclose shot which is designated as
delayed. Incorrect configuration can result in no protection being enabled.
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
Configuration > Function Config
Parameter Setting Options Settings
Default Gn1 Gn2 Gn3 Gn4
51N Earth Fault Enabled
Disabled
Disabled
Functions > Protection > 51N > Gn 51N-n
Parameter Setting Options Settings
Default Gn1 Gn2 Gn3 Gn4
Element Enabled
Disabled
Disabled
Dir. Control
10
Non-Dir
Forward
Reverse
Non-Dir
Setting 0.05 to 2.5 ⋅ I
rated
, Δ 0.05
I
rated
0.5 ⋅
I
rated
Char DTL
IEC-NI
IEC-VI
IEC-EI
IEC-LTI
ANSI-EI
ANSI-MI
ANSI-VI
IEC-NI
5.20.5
10
Applies only to devices with VT inputs.
Protection and Automation Functions
5.20 51N Time-Delayed Earth Fault – Calculated
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual 291
C53000-G7040-C014-1, Edition 11.2019
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