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

10.2 CURRENT DIFFERENTIAL (87L) 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 two CT/VT modules: F8F and L8F.
1. CTs and VTs are connected to L90 CT/VT modules as follows:
– CT1 circuitry is connected to the F1 to F3 terminals of the F8F module (three-phase CT inputs, CT bank "F").
– CT2 circuitry is connected to the F1 to F3 terminals of the L8F module (three-phase CT inputs, CT bank "L").
– VT1 circuitry is connected to the F8 terminals of the F8F module (single-phase VT for synchrocheck 1, VT bank "F").
– VT2 circuitry is connected to the F8 terminals of the L8F module (single-phase VT for synchrocheck 2, VT bank "L").
– VT3 circuitry is connected to the F5 to F7 terminals of the F8F modules (three-phase VT for distance, metering, syn-
chrocheck, charging current compensation, etc.; VT bank "F").
2. The CTs and VTs are configured according to the following ratios and connections (EnerVista UR Setup example
shown):
10
10-6
Figure 10–1: BREAKER-AND-A-HALF APPLICATION
L90 Line Current Differential System
10 APPLICATION OF SETTINGS

10.2.7 BREAKER-AND-A-HALF

GE Multilin