Comparison of the measurements of current transformers

Project Description

The comparison is carried out for the following current ratios: 4000, 2000, 1000, 500, 100, 5, 1 and 0.1/secondary 5 A. All ratios should be measured with a burden 5 VA at unity power factor. Measurements will be performed with the following % of rated current: 120, 100, 20 and 5. For ratios with primary current less than 5 A the point 5 % should be replaced by 10 %.
Traveling standards: 5 Instrument Current Transformers as follows: Tettex 4720, CLA 2.2, CLA 3.2, CLB 10 and I 523.
The comparison is carried out as Supplementary Comparison EURAMET.EM-S30.
The comparison is organized and funded within the framework of PHARE project BG 2005/017-353.02.02, LOT 1

Final Report 2009-10-26

The comparison has been completed and results are published in the KCBD

The supplementary comparison was carried out between CMI, Czech Republic and BIM, NCM Bulgaria in the field of current transformer ratio measurements. The current errors and phase displacement of the traveling standards, current transformers: Tettex 4720, CLA 2.2, CLA 2.2, CLA 3.2, CLB 10, I 523 were determined at 50 Hz, 5 VA burden at unity power factor at ratios: primary (4000, 2000, 1000, 500, 100, 5, 1 and 0.5) A/ secondary 5 A. Both participants used their own standard measurement method.
The obtained results show good agreement for all of the current ratio error measurements (except for the measurements at 2 kA) and for the current phase displacement measurements (the agreement on several measurement points is marginal). The aim of the comparison was to demonstrate the improvement and extension of the calibration and measurement capabilities (CMCs) of BIM in this working field and to support the improved CMCs in Appendix C of the CIPM mutual recognition arrangement (MRA).