Settings Menu - Siemens Reyrolle 7SR5 Manual

Protection and Automation Functions
5.1 21LB Load Blinder
[fo_function21LBimpedancesetting1, 1, en_US]
NOTE
i
i
The equivalent primary impedance to the above:
Where:
I = CT primary rating (A)
rated,prim
I = CT secondary rating (A)
rated,sec
I = Secondary current = 1.5 ⋅ I
sec
V = VT primary rating (phase-phase V)
rated,prim
V = VT secondary rating (phase-phase V)
rated,sec
Z = Primary impedance
prim
Z = Secondary impedance
sec
21LB-3P Angle (+ve and -ve) Setting ('b' and 'c')
A setting of 20 degrees will allow blocking of the overcurrent element for system load power factors between
0.94 and unity.
21LB-3P V Setting
pps
The blinder is only operational during normal load levels of reverse load flow. Where reverse current flow is
caused by a system fault the positive sequence voltage will reduce significantly. To facilitate load blinder oper-
ation the system should be substantially balanced i.e. positive phase sequence voltage will be high. A setting
of 0.95 V is selected i.e. 21LB-V
rated
21LB-3P I Setting
nps
The blinder is only operational during normal load levels of reverse load flow. The system should be substan-
tially balanced i.e negative phase sequence current will be low. A 21LB-3P I

Settings Menu

5.1.5
Functions > Function Config
Parameter
21LB Load Blinder
148
(e.g. nominated max. reverse load current)
rated,sec
setting = 0.95 ⋅ 63.5 = 60 V.
1
Range
Enabled
Disabled
Reyrolle 7SR5, Transformer Protection Device, Device Manual
setting = 0.05 I
2
Settings
Default Gn1 Gn2
Disabled
C53000-G7040-C015-1, Edition 11.2019
is selected.
rated
Gn3 Gn4