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.
Parameter: 21LB-3P Inhibit
•
Default setting: No
Where the reverse load flow current may cause incorrect operation of directional overcurrent protection
this function is used to inhibit the 50 element when the measured power factor is within defined limits.
Parameter: 21LB-1P Inhibit
•
Default setting: No
Where the reverse load flow current may cause incorrect operation of directional overcurrent protection
this function is used to inhibit the 50 element when the measured power factor is within defined limits.
Settings Example
Each instantaneous element has an independent setting for pickup current and a follower definite time lag
(DTL) which can be used to provide time grading margins, sequence co-ordination grading or scheme logic.
The “instantaneous” description relates to the pickup of the element rather than its operation.
Instantaneous elements can be used in current graded schemes where there is a significant difference
between the fault current levels at different relay points.
The instantaneous element is set to pickup at a current above the maximum fault current at the next down-
stream relay location, and below its own minimum fault current level. The protection is set to operate instan-
taneously and is often termed Highset Overcurrent. A typical application is the protection of transformer
HV connections – the impedance of the transformer ensuring that the LV side has a much lower level of fault
current.
The 50-n function elements have a very low transient overreach i.e. their accuracy is not appreciably affected
by DC offset transients associated with fault inception.
Settings Menu
Functions > Function Config
Parameter Range Settings
Default Gn1 Gn2 Gn3 Gn4
50 Overcurrent Enabled
Disabled
Disabled
Functions > Protection > 50 > Gn 50-n
Parameter Range Settings
Default Gn1 Gn2 Gn3 Gn4
Element Enabled
Disabled
Disabled
Measurement RMS
Fundemental
RMS
5.11.5
Protection and Automation Functions
5.11 50 Instantaneous Overcurrent – Phase
Reyrolle 7SR5, Overcurrent Protection Device, Device Manual 211
C53000-G7040-C014-1, Edition 11.2019
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