Derived Earth Fault (67/50N, 67/51N); Figure 2-7 Derived Earth Fault - Siemens 7SR21 Manual

2.6

Derived Earth Fault (67/50N, 67/51N)

Voltage Inputs:
Current Inputs:
Disable:
Map Pickup LED:
Other protection functions may overlap with these functions during testing, it may be useful to disable some
functions to avoid ambiguity. Derived EF, Measured EF Sensitive EF & Restricted EF protections can be
Enabled/Disabled individually or as groups in the 'Function Config' menu.
Derived EF elements can be separated from Measured EF and sensitive EF by arrangement of the secondary
injection circuit by shorting/disconnecting I
If any of these elements are defined as directional the correct voltage phase direction will be required to produce
an operation of those elements.
©2010 Siemens Protection Devices Limited
7SR21 & 7SR22 Argus Commissioning and Maintenance

Figure 2-7 Derived Earth Fault

V (V ), V (V ), V (V )
L1 A L2 B L3 C
I (I ), I (I ), I (I ),
L1 A L2 B L3 C
37, 46, 49, 60CTS, 50CBF, 60CTS, 46BC, 79
51N-n/50N-n - Self Reset
and I inputs.
4 5
Chapter 6 Page 25 of 69