7SR210 & 7SR220 Commissioning & Maintenance Guide
Page 74 of 82
© 2013 Siemens Protection Devices Limited
The design of a Load Blinder 3Ph is based on the theory that protection blocking should be issued only during
definable allowable system power flow conditions i.e. an overcurrent blocking signal can only be issued when:
§
Positive Sequence Voltage
Vpps
is not significantly changed, when the Vpps is above the
21LB-3P VPPS
Setting.
AND
§
Negative Sequence Current
Inps
is lower than
21LB-3P INPS Setting
AND
§
Distributed generators feed in PPS current into the system. In case of high load in system due to
distributed generation hence resulting in change of
Zpps.
Zpps
is calculated from
Vpps
and
Ipps
. The magnitude and angle of
Zpps
is compared with
21LB-3P
Impedance
and
21LB-3P Angle
to determine if the impedance is in operate or block and/or FWD or
REV zone.
+R
+X
Phase
Fault
Block
Zone
Load
Impedance
b
a
Nominal
Impedance
Z = 1p.u. =
V
L
/ (√3 x I)
c
-R
-X
Vpps value
Point 1
Point 2
Point 3
Point 4
0
360
Trip Level
I = Vs / Z
Operate
Zone
a = 21LB-3P Impedance
setting
b = 21LB-3P Angle +ve
setting
c = 21LB-3P Angle -ve
setting
Point 6
Point 5
Block
Zone
Load
Impedance
b
a
c
Point 7
Point 10
Point 9
Point 8
Figure 3.5-2 Load Blinder (21) Boundary Points
Summary of Contents for Argus 7SR21
Page 1: ...Energy Management 7SR21 7SR22 Argus Overcurrent Relay Reyrolle Protection Devices ...
Page 2: ......
Page 4: ...Contents 7SR11 and 7SR12 Page 2 of 2 2018 Siemens Protection Devices Limited ...
Page 185: ...7SR210 Settings Guide Unrestricted 2018 Siemens Protection Devices Limited Page 61 of 61 ...
Page 277: ...7SR220 Settings Guide Unrestricted Page 72 of 107 2013 Siemens Protection Devices Limited ...
Page 382: ...7SR220 Technical Manual Chapter 4 Page 2 of 96 2017 Siemens Protection Devices Limited ...
Page 386: ...7SR220 Technical Manual Chapter 4 Page 6 of 96 2017 Siemens Protection Devices Limited ...
Page 398: ...7SR220 Technical Manual Chapter 4 Page 18 of 96 2017 Siemens Protection Devices Limited ...
Page 414: ...7SR220 Technical Manual Chapter 4 Page 34 of 96 2017 Siemens Protection Devices Limited ...
Page 466: ...7SR220 Technical Manual Chapter 4 Page 86 of 96 2017 Siemens Protection Devices Limited ...
Page 468: ...7SR220 Technical Manual Chapter 4 Page 88 of 96 2017 Siemens Protection Devices Limited ...
Page 470: ...7SR220 Technical Manual Chapter 4 Page 90 of 96 2017 Siemens Protection Devices Limited ...
Page 472: ...7SR220 Technical Manual Chapter 4 Page 92 of 96 2017 Siemens Protection Devices Limited ...
Page 643: ...Unrestricted ...