7SR11 & 7SR12 Applications Guide
©2017 Siemens Protection Devices Limited
Chapter 7 Page 17 of 48
Block 50-1
INCOMER
51-1
50-1 (100ms)
51-1
F2
F1
Power
flow
50-1
(0ms)
50-1
(0ms)
50-1
(0ms)
50-1
(0ms)
Blocking outputs for circuit faults
Figure 2.5-2 Blocking Scheme Using Instantaneous Overcurrent Elements
Typically a time delay as low as 50ms on the incomer 50-1 element will ensure that the incomer is not tripped for
outgoing circuit faults. However, to include for both equipment tolerances and a safety margin a minimum time
delay of 100ms is recommended.
This type of scheme is very cost effective and provides a compromise between back-up overcurrent busbar
protection and dedicated schemes of busbar protection.
Instantaneous elements are also commonly applied to autoreclose schemes to grade with downstream circuit
reclosers and maximise the probability of a successful auto-reclose sequence – see section 4.
Summary of Contents for Argus 7SR11
Page 1: ...Energy Management 7SR11 7SR12 Argus Overcurrent Relay Reyrolle Protection Devices ...
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Page 4: ...7SR11 7SR12 Argus Contents 2015 Siemens Protection Devices Limited Page 2 of 2 ...
Page 170: ...7SR120 Technical Manual Chapter 4 Page 2 of 84 2017 Siemens Protection Devices Limited ...
Page 174: ...7SR120 Technical Manual Chapter 4 Page 6 of 84 2017 Siemens Protection Devices Limited ...
Page 196: ...7SR120 Technical Manual Chapter 4 Page 28 of 84 2017 Siemens Protection Devices Limited ...
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Page 244: ...7SR120 Technical Manual Chapter 4 Page 76 of 84 2017 Siemens Protection Devices Limited ...
Page 246: ...7SR120 Technical Manual Chapter 4 Page 78 of 84 2017 Siemens Protection Devices Limited ...
Page 254: ...7SR11 7SR12 Installation Guide Chapter 5 Page 2 of 32 2017 Siemens Protection Devices Limited ...
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