Multi-Vendor Merging Units Applied to a Transformer Protection Element, and the Impact of Time Synchronization Loss
This month’s Featured Technical Paper is from the Proceedings of the 2026 International Conference of Doble Clients. The paper is titled: Multi-Vendor Merging Units Applied to a Transformer Protection Element, and the Impact of Time Synchronization Loss
Abstract
Testing of a power transformer protection scheme (ANSI 87T) is crucial to guarantee its proper operation. In a digital substation, merging units (MUs) are a key component as well as a common time reference; typically, MUs from the same brand are used. Talking about Intelligent Electronic Device (IED) interoperability, MUs from different manufacturers are possible.
This paper will present challenges in interoperability, the use of MUs from different manufacturers like sampling alignment in an 87T protection scheme. This paper will also present an explanation of the impact of loss time synchronization in which IEDs may detect misalignment as a fault, so a robust time synchronization mechanism is essential in multi-vendors to maintain protection integrity.