Tap Changer Analysis

On-load tap changers (OLTC) play a vital role in regulating the voltage level in the electrical grid. Depending on the load, the transformer turns ratio has to be adapted during operation by the OLTC. These mechanical switching operations can lead to wear and tear of the tap changer contacts over time. Therefore, tap changer analysis focuses on static contact problems of the tap selector and of the diverter switch. In addition, a dynamic resistance and motor current measurement can be performed to analyse the transient switching operation for each tap position.

Expert recommends


TESTRANO 600 is the world’s first portable, three-phase test system which supports all common electrical tests on single- and three-phase power and distribution transformers.

TESTRANO 600 provides you with a convenient way of testing to gain a comprehensive insight into the condition of every part of your power transformer. It can be operated using TESTRANO TouchControl on the integrated display, or by using our Primary Testing ManagerTM software on your laptop. This makes it ideal for routine and diagnostic testing onsite or during factory acceptance tests (FAT).

Benefits of this solution

Other solutions

CPC 100 + CP SB1 + PTM

By combining the CPC 100 with the CP SB1 you can test all three phases and the tap changer automatically. Thus, power transformer testing becomes faster and safer as the rewiring effort and the likelihood of measurement errors are minimized.

The transformer ratio and winding resistance are automatically measured in all three phases (in sequence) in all tap changer positions. The measurement results are recorded by the CPC 100 and can be analysed with the accompanying Primary Test Manager™ (PTM) software.


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