The scope of this TSS is limited to the testing of PMU electrical performance. As of this revision of the TSS@ the standard for PMU performance is IEEE Std C37.118.1?-2011@ IEEE Standard for Synchrophasor Measurements for Power Systems as modified by IEEE Std C37.118.1a?-2014.1 This TSS will be revised as the standard for PMU performance is revised. Users are encouraged to check for the latest revision of this document. Purpose This test suite specification (TSS) provides organizations that are testing phasor measurement unit (PMU) performance with a suite of unambiguous test plans in accordance with the Smart Grid Interoperability Panel (SGIP) Interoperability Process Reference Manual (IPRM). This TSS further provides requirements for equipment used for the testing of PMUs@ requirements for the measurements made by PMU test equipment@ and requirements for the reporting of PMU measurements. Test plans and requirements in this TSS are more specific than requirements of the standard for PMU performance. The standard specifies the test signals to be input to a PMU under test and the performance limits that must be met by the PMU@ but neither specifies the test procedure to be used nor the specific calculations made to determine PMU performance. Without specific test procedures and calculations@ tests that are implemented by different test designers may yield different results. Furthermore@ some ambiguities in the standard are identified and this TSS sets requirements based on a single interpretation of the ambiguous clauses. In accordance with the SGIP IPRM@ the authors of this document will work closely with the standard setting organizations to resolve the ambiguities in future revisions of the standard. This TSS may be revised thereafter to reflect the standard's revision once it is published. PMU testing organizations that participate in The Institute of Electrical and Electronics Engineers Conformance Assessment Program (ICAP) PMU Conformance Assessment Program must comply with the test plans and requirements in this document. Conformance with this TSS is assessed as part of the ICAP program.