IEEE Std C57.13.7:2018 pdf download.IEEE Standard for Current Transformers with Maximum Milliampere Secondary Current of 250 mA.
IEEE Std C57.13.7 is intended to define the requirements for CTs with a maximum of secondary output of 250 mA. These requirements of ratios, accuracy classes, burdens, and test methods supplement but are not subordinate to IEEE (‘57.13. These transformers arc for both indoor and outdoor applications.
1.2 Purpose
The purpose of this standard is to provide the performance requirements for electrical system and test interchangeability for CTs with milliampere output.
2. Normative references
The following referenced documents are indispensable for the application of this document (i.e., they shall be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.
IEEI- StdC57.13T1, IEEE Standard Requirements for Instrument Transformers.NCSL Z540.3:2006, Requirements for the Calibration of Measuring and Test Equipment.
3. Definitions, acronyms, and abbreviations
3.1 Definitions
The requirements for metering are defined in 5.1 and 5.2 of IEEE Std C57. 1 3TM..2008 as applicable to CTs. In Canada, regulatory references are specifically made to 80 mA and 100 mA and therefore require a specific category for each of them. The IEEE Standards Dictionary Online should be consulted for terms not defined in this cIause.
3.2 Acronyms and abbreviations
current transformer
DUT transformer under test
RCF ratio correction factor
TCF transformer correction factor
TUR test uncertainty ratio
4. Ratings
Current ratings of 80-mA class measuring CTs shall be in accordance with the values in Table 1.
6.3 Requirements for accuracy and accuracy of calibration systems
The accuracy pcrfbrmance shall be in accordance with Table 5.
The accuracy ratings of all milliampere CTs shall be verified and determined using calibration techniques and methods with an overall uncertainty. i.e., a test uncertainty ratio (TUR) of 4:1. In other words, the tolerance of the milliampere CT specification being tested shall be equal to or greater than four times the combined uncertainties of all the measurement standards employed in the test as specified in NCSL Z540.3:2006. For example, for milliampere CTs with accuracy ratings of 0.3 that have been designed for metering applications, the deviation from the marked values shall remain within 0.3% for ratio and 3 rnrad (10.3 mm) for phase angle. Therefore, the overall uncertainty of the calibration system to verify the corresponding accuracy class shall be equal to. or less than, 0.075% for ratio and 0.75 mrad (2.6 mm) for phase angle.
The calibration system used for accuracy tests shall be traceable to the SI units through national/international standards maintained by a National Metrology Institute. Records of accuracy verification for the calibration systems by an independent laboratory shall be regularly maintained. Traceability is a process by which the assigned value of a measurement is compared. directly or indirectly, through a series of unbroken chain comparisons to the value established by appropriate national/international standards all having stated uncertainty.IEEE Std C57.13.7 pdf download.