IEEE C37.238-2017 pdf free downlaod – IEEE Standard Profle for Use of IEEE 1588™ Precision Time Protocol in Power System Applications.
5. Relationship to other standards
5.1 IEEE Std 1588:2008 IEEE Std 1588:2008, Precision Time Protocol, provides methods allowing accurate time and frequency transfer from one point (a grandmaster) to another (a slave) over a communications network comprising transparent clocks (TCs) and boundary clocks (BCs). It provides several alternative methods, but does not establish performance requirements. It is most often used over Ethernet, but can be used with many other network technologies. Thus, it can be applied in a wide variety of diferent industries. To address the issues that arise from the many options it provides, IEEE Std 1588:2008 recommends the creation of ‘profles.’ To enhance interoperability within an industry, a standard organization chooses particular options (from the selection provided by IEEE Std 1588:2008) appropriate for a specifc application. Profles may establish specifc performance requirements. Additional features defned in a profle, but not present in IEEE Std 1588:2008 are called extensions.
5.2 IEC/IEEE 61850-9-3:2016 This standard is a profle of IEEE Std 1588:2008 jointly developed by the IEEE Power and Energy Society Power System Relaying Committee (PSRC) Working Group H24 and Substations Committee Working Group C7, and the IEC Technical Committee 57 Working Group 10, as a common base profle for the electric power industry. It is a Layer 2, peer-to-peer profle of based on J.4 of IEEE Std 1588-2008. It specifes options to be used and device performance, with the goal to deliver time to slaves with an accuracy of one microsecond or better over a network comprising up to 15 TCs. An optional extension allows operation with doubly attached clocks for critical, high-availability applications. Transmission of local time through the ALTERNATE_ TIME_OFFSET_INDICATOR is optionally supported.
5.3 IEEE Std C37.238 This standard is an extension of IEC/IEEE 61850-9-3:2016, developed by Working Group H24/Sub C7 to provide additional functionality. The additional functions comprise two type, length, and values (TLVs): one mandatory TLV, providing additional information to monitor clock performance in real time, and an optional TLV, providing local time zone information, to ease transition from former Inter-Range Instrumentation Group B (IRIG-B) systems and for local display applications.
IEEE Std C37.238-2011 was superseded upon the IEEE-SA Standards Board approval of both IEC/IEEE 61850-9-3:2016 and this revision. NOTE—Even if it receives Announce messages with the IEEE C37.238 TLV attached, an IEEE C37.238 clock cannot detect that all TCs or BCs up to the grandmaster are also IEEE C37.238 compliant, so it is the responsibility of the network engineer to ensure this, also considering reconfguration after failure of any network element [Rapid Spanning Tree Protocal (RSTP) bridge or clock].
5.4 Confguration The default confguration for the domain, defaultDS.domainNumber, shall be 254. Implementation claiming conformance to this standard shall be able to confgure domain numbers of the range 0 to 127 and the single value 254. The value 254 shall be used only for implementations of this profle that are conformant to Annex F of IEEE Std 1588-2008.
NOTE 1—This complies with IEEE Std 1588-2008 with the exception of the use of the reserved domain 254. The value 254 is an exception granted to this profle. For operation in an IEC/IEEE 61850-9-3 network, domain number shall be confgured to IEC/IEEE 61850-9- 3 domain (93 is recommended).
NOTE 2—Network engineering should ensure that all clocks participating in the PTP time distribution are set to the same domain(s) (see 7.9 of IEC/IEEE 61850-9-3:2016). More than one domain may be in use; for example, to allow redundant masters and/or network paths. See also Annex E. Devices conformant to this standard shall have non-volatile settings that preserve their confguration during a power cycle, including the ability to be confgured to comply with IEC/IEEE 61850-9-3:2016.IEEE C37.238 pdf download