Breaker-And-A-Half - GE L90 Instruction Manual

9 APPLICATION OF SETTINGS
Assume a breaker-and-the-half configuration shown in the figure below. This section provides guidance on configuring the
L90 relay for this application. The L90 is equipped with 2 CT/VT modules: F8F and L8F.
1. CTs and VTs are connected to L90 CT/VT modules as follows:
– the CT1 circuitry is connected to the F1 to F3 terminals of the F8F module (3-phase CT inputs, CT bank "F").
– the CT2 circuitry is connected to the F1 to F3 terminals of the L8F module (3-phase CT inputs, CT bank "L").
– the VT1 circuitry is connected to the F8 terminals of the F8F module (1-phase VT for Synchrocheck 1, VT bank "F").
– the VT2 circuitry is connected to the F8 terminals of the L8F module (1-phase VT for Synchrocheck 2, VT bank "L").
– the VT3 circuitry is connected to the F4 to F7 terminals of the F8F modules (3-phase VT for distance, metering, syn-
chrocheck, charging current compensation, etc.; VT bank "F").
VT1
2. The CTs and VTs are configured according to the following ratios and connections (enerVista UR Setup example
shown):
3. The sources are configured as follows:
Source 1: – First current source for current differential,
– voltage source for charging current compensation,
– current source for Breaker Failure 1, and
– voltage source for Synchrocheck 1.
GE Multilin
CB1
CT1
1PH
VT3
Figure 9–1: BREAKER-AND-A-HALF APPLICATION
L90 Line Differential Relay
9.2 CURRENT DIFFERENTIAL (87L) SETTINGS

9.2.7 BREAKER-AND-A-HALF

CB2
CT2
VT2
1PH
PROTECTED
LINE
831783A1.CDR
9
9-5