7SG11 Argus Technical Reference
©2013 Siemens Protection Devices Limited
P20007 Page 59 of 71
P300012 REF / Primary
Balanced Earth-fault
Restricted Earth-fault
Figure 3.5-1
Balanced and Restricted Earth-fault protection of Transformers
non-linear
resistor
series stabilising
resistor
Argus REF
element
relay circuit
P300012 REF / Secondary
Figure 3.5-2
Restricted Earth-fault Secondary Circuit
Composite overcurrent and REF protection can be provided using a multi-element relay as Figure 3.5-3.
P300012 REF / Primary
25
45
49
53
46
50
54
26
non-linear resistor
series
stabilising
resistor
overcurrent
elements
REF
element
Figure 3.5-3
Composite Overcurrent and Restricted Earth-fault Protection