One very important component of a power transformer is the on-load tap changer (OLTC). The principal of the Dynamic Resistance Measurement (DRM) was developed to analyze the switching process of OLTCs.
The latest software version 3.40 of the CPC 100 Toolset and Primary Test ManagerTM (PTM) includes the new “OLTC scan” function, which allows DRM to be performed with the CPC 100 + CP SB1 test system.
The new “OLTC scan” can be performed as a supplementary measurement in order to analyze the OLTC’s switching process. DC current is injected in the same way as in static winding resistance measurement with the addition of recording the dynamic behaviour of the diverter switch. Based on this non-invasive testing method, failures can be detected without opening the OLTC compartment. As a result, the reliability of the OLTC can be improved, maintenance costs can be reduced and most importantly, unexpected and expensive outages can be avoided.
With the integration of the “OLTC scan” functionality, the multifunctional CPC 100 + CP SB1 test system now allows comprehensive tap changer diagnosis on all phases.
Analysis and comparison of test results
Beside the testing possibilities, the Primary Test Manager (PTM) software makes it possible to analyze and compare the switching process of the individual taps and phases using unique filtering options. As a result additional parameters of the switching process can be extracted for a more comprehensive analysis of the OLTC condition. Customers can download the latest software version 3.40 of the CPC 100 Toolset and Primary Test Manager free-of-charge from the customer area of the OMICRON website.