Manual MRG3
SEG Electronics GmbH
DOK-TD-MRG3, Rev. D
11
Figure 3.6: Connection diagram with time over current protection and detection of the residual voltage
For the unit version including the earth fault directional feature (ER unit type), the residual voltage
U can be generated internally in the secondary measuring circuit. The device shall then be encod-
ed as described in chapter 3.1.8. Thus, star connection of voltage transformers is imperative. For
the detection of residual voltage from the open delta winding, it is possible to connect the voltage
transformer directly to B1 and A2. Connection of voltage transformers in isolated/compensated
grids is explained in chapter 4.7.3