Time synchronization is a basic function common to all automation systems. The accuracy and resolution of event timestamps can be a deciding factor in the success of an automation project. The new standard for substation communication, IEC 61850, specifies that SNTP (Simple Network Time Protocol) is one of the mandatory synchronization mechanisms. The availability of SNTP in source code form induces many IED vendors to implement SNTP almost as an afterthought. However, off-the-shelf implementations are seldom optimized for accuracy and typically provide only a few tens of milliseconds of synchronization potential. There is a better way. Through careful attention to detail, time synchronization on the order of microseconds is achievable using commonly available hardware and software. This article will show how standard off-the-shelf PCs, running the standard Windows XP operating system, can achieve orders of magnitude improvements over simple implementations.
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