OMICRON Magazine

GOOD VIBRATIONS Listen to your on-load tap changer, it may be trying to tell you something. The on-load tap changer (OLTC) is an essential component of a power transformer that helps maintain a stable voltage level within the electrical grid. It adjusts the transformer turns ratio, which regulates the system voltage. Various diagnostic tools are available to assess the static and dynamic characteristics of the tap-changer. While a DC winding resistance measurement can reveal wear and tear of the main contacts, the dynamic resistance measurement is sensitive to timing changes and current interruptions during the switching operation. The vibro-acoustic measurement (VAM) is a new tool in the diagnostic toolbox that records the vibrations produced during switching operations. This means that all the OLTCs’ components that create a certain vibration level can be analyzed and evaluated. It’s even possible to conduct an in-depth condition assessment by combining it with our well-established dynamic resistance measurement (DRM). The best results are achievable when the VAM and DRM readings are compared with reference data, either from the same unit or a comparable sister unit. 6

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