Ct Saturation Analysis Tool - GE L30 Instruction Manual

9.1 CT REQUIREMENTS 9 APPLICATION OF SETTINGS

9.1.2 CT SATURATION ANALYSIS TOOL

The CT saturation analysis tool is an Excel spreadsheet provided for users to analyze the L30 reliability during CT satura-
tion caused by an external fault, to investigate the effect of adjusting 87L settings, and to examine the possibility of reducing
the CT requirement.
The tool utilizes the CT model and CT saturation calculation algorithm proposed by the IEEE Power System Relaying Com-
mittee (PSRC), and it simulates the analog/digital signal processing and data calculations in the L30. The figure shows the
interface.
Figure 9–1: CT SATURATION ANALYSIS TOOL MAIN PAGE
For a system where the CTs are already installed, the CT and system parameters are known. Use the procedure described
in the tool to analyze the L30 security during CT saturation and investigate the effect of adjusting 87L settings.
The CT saturation analysis tool allows you to check the application, knowing CT parameters, fault current levels, and distri-
bution through all breakers from short circuit studies, and to analyze L30 performance, having an ability to adjust settings
as needed. The tool has all instructions to perform analysis.
Once all data is entered, by clicking the Analyze button, you can observe differential and restraint currents through the sim-
ulated fault in the Results tab, shown as follows. The application is considered secure when the worst through the plot
Irestr/Idiff > 1.25 with selected settings and all fault scenarios considered.
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Figure 9–2: TOOL RESULTS FOR CURRENTS
9-2 L30 Line Current Differential System GE Multilin