ABB RELION 620 Series Technical Manual page 483

1MAC504801-IB E
620 series ANSI
Technical Manual
. . . . . .
Incoming / Outgoing
GUID-A04D625C-62E6-47A1-9306-B365FF784AAD V1 EN
Figure 225: Differential protection on Bus transfer scheme (Single phase
representation)
Figure 226shows an arrangement of double busbar scheme with two feeders and a bus
coupler. Here both the buses, main bus and reserve bus are protected by two separate 3-
phase high impedance function. Here it is important that along with current input, logic
also needs to be created for feeding correct current input to the differential protection. This
logic is created by hard wires connection and using disconnector positions.
Feeder
Section 4
Protection functions
Main Bus
Transfer Bus
Stabilizing
resistor R
s
Differential protection
(87A, 87B, 87C)
477