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How do I set the CT ratio and FLA on a C445 w/ external CT's?

The C445 Motor Management Relay can control and monitor applications up to 800 amps. Above 136 amps, external current transformers (CT’s) are used to measure current flow. Parameterization is simply entering the ratio of the CT’s as shown below using either the Monitoring User Interface C445UM or Power Xpert inControl Software. The XCT-300-5 CT parameter values are shown in Figure 1. The XCT-300-5 CT will accommodate motor nameplate Full Load Amps (FLA) of 60 to 300 amps. Additional information may be found in the User Manual MN042003EN.

Figure 1 - CT Ratio Parameterization


After the CT Ratio’s are set, the Motor Nameplate FLA value can be set in the Motor Configuration menu. Note that the FLA range has shifted to reflect the CT range as shown in Figure 2.

Figure 2 - Motor FLA Range Shift to XCT Range


The available XCT unit parameters are shown in Table 1.

Table 1 - XCT... Parameterization and FLA Range Values