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Sepam MCS025 Synchro-check module - why are asterisks (" *** " or stars) displayed for the differences in the measurements screen of SFT2841?

This FAQ provides some suggestions for troubleshooting an issue that is sometimes encountered with the Sepam MCS025 module.

In some cases, especially during the commissioning or testing phases of a project, a user may notice that asterisks (or stars) are displayed in the Measurements screen of SFT2841 for the "Differences measured by MCS025."  The issue that will be discussed in this FAQ is depicted in the screen capture below.

The most likely reason for this phenomenon is that either no voltage is being applied to the voltage inputs on the MCS025 module itself, or that the voltages being applied are below the "Us Low" threshold programmed in the tab for the ANSI 25 protection function.  The following screen shot shows the screen where the ANSI 25 protection function settings can be modified:

Referring to the first screen capture, it is important to note that the Measurements screen in SFT2841 does not display numerical values for the voltages applied to the MCS025 module.  In other words, all voltage values shown in the Measurements screen refer to values measured by the Sepam base unit, and not the MCS025 module.  This is true for all versions of SFT2841 up to and including V14.1.

To resolve this issue, ensure that your ANSI 25 protection settings are correct, and verify that the voltage you are applying to the MCS025 voltage inputs is an AC voltage at the Nominal Frequency programmed in the relay.  Once you have applied a valid voltage signal to the MCS025 voltage inputs on both "sides," the display should update correctly.

As with all issues involving Sepam accessories, it is also advisable to download the SFTSAV report from the relay, and to check the Diagnostics screen of SFT2841 while connected to the relay.  However, in most cases, the solution described above should resolve the issue in the vast majority of cases.


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