Discussion on the papers “A new null method of testing instrument transformers, and its application”, by Mr. Shotter, “Some accessory apparatus for precise measurements of alternating current”, by Messrs. Spilsbury and Arnold, and “Precision testing of current transformers”, by Dr. Arnold, before the Meter and Instrument Section, 7th February, 1930

1930 ◽  
Vol 68 (403) ◽  
pp. 906-911
Keyword(s):  
Alternating Current ◽  
Testing Instrument ◽  
Current Transformers ◽  
Instrument Transformers ◽  
Precision Testing

Simulation Model for Assessing Operational Performance of Current Transformers

2007 ◽  
Vol 18-19 ◽  
pp. 71-77
Author(s):  
I. Sule
Keyword(s):  
Simulation Model ◽  
Current Transformer ◽  
Operational Performance ◽  
Current Transformers ◽  
Correct Operation ◽  
Operational Conditions ◽  
Secondary Current ◽  
Protection Scheme ◽  
The Core ◽  
Instrument Transformers

In determining the correct operation of relays of a protection scheme, proper representation of instrument transformers and their behavior in conditions where there can be saturation, is very critical. The main objective of this paper is to develop simulation model for assessing the operational performance of Current Transformer (CT). In order to test the validity of the developed model, three cases of CT operational conditions were considered, with data collected from Gombe, 330/132/33kV PHCN substation. The simulation results revealed various configuration performance responses that could affect relay protective schemes to different degrees. The CT responses revealed that the secondary current and voltage were distorted when the core flux linkages exceeded the set 9.2 pu saturation limit. It is concluded that the model developed for the CT of interest yield satisfactory results.

scholarly journals Are Inductive Current Transformers Performance Really Affected by Actual Distorted Network Conditions? An Experimental Case Study

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 927 ◽  
Author(s):  
Alessandro Mingotti ◽  
Lorenzo Peretto ◽  
Lorenzo Bartolomei ◽  
Diego Cavaliere ◽  
Roberto Tinarelli
Keyword(s):  
Operating Conditions ◽  
Accuracy Evaluation ◽  
Current Transformers ◽  
Need To Evaluate ◽  
Instrument Transformers ◽  
Instrument Transformer ◽  
Secondary Result ◽  
Error Index ◽  
Accuracy Performance

The aim of this work is to assess whether actual distorted conditions of the network are really affecting the accuracy of inductive current transformers. The study started from the need to evaluate the accuracy performance of inductive current transformers in off-nominal conditions, and to improve the related standards. In fact, standards do not provide a uniform set of distorted waveforms to be applied on inductive or low-power instrument transformers. Moreover, there is no agreement yet, among the experts, about how to evaluate the uncertainty of the instrument transformer when the operating conditions are different from the rated ones. To this purpose, the authors collected currents from the power network and injected them into two off-the-shelf current transformers. Then, their accuracy performances have been evaluated by means of the well-known composite error index and an approximated version of it. The obtained results show that under realistic non-rated conditions of the network, the tested transformers show a very good behavior considering their nonlinear nature, arising the question in the title. A secondary result is that the use of the composite error should be more and more supported by the standards, considering its effectiveness in the accuracy evaluation of instrument transformers for measuring purposes.

A Novel Method for Investigating the Frequency Dependent Behavior of Instrument Transformers

2014 ◽  
Vol 494-495 ◽  
pp. 1477-1481
Author(s):  
Yong Xin Feng ◽  
Zhao Li ◽  
Ya Qi Gao ◽  
Bing Ran Shao ◽  
Xue Wen Ding ◽  
...  
Keyword(s):  
Measurement System ◽  
Current Transformers ◽  
Frequency Dependent ◽  
Frequency Responses ◽  
System A ◽  
Dependent Behavior ◽  
Instrument Transformers ◽  
Computer Based ◽  
Novel Method ◽  
High Voltage System

This paper describes the structure and the principle of the NI DAQ based measurement system used for investigating the frequency dependent behavior of instrument transformers in the high voltage system. A computer based NI DAQ card is utilized as the data acquisition system in the new measurement system. The software digital filter and the phase locked loop are implemented to obtain the magnitude and phase angle, respectively. With this measurement system, we investigated frequency responses of several voltage and current transformers at the converter station of the Germany railway.

scholarly journals Test equipment and its effect on the calibration of instrument transformers

2018 ◽  
Vol 7 (1) ◽  
pp. 339-347
Author(s):  
Enrico Mohns ◽  
Peter Räther
Keyword(s):  
Uncertainty Budget ◽  
Current Transformer ◽  
National Standards ◽  
Test Equipment ◽  
Management Systems ◽  
Testing Instrument ◽  
Quality Management Systems ◽  
Ratio Error ◽  
Instrument Transformers ◽  
A Current

Abstract. State-approved test centres in Germany supplying accuracy tests for instrument transformers must, in the future, provide measurement uncertainty budgets for their quality management systems. In this work, the cause of ratio error and phase displacement of instrument transformers are therefore discussed. The traceability to the national standards of PTB, the attainable uncertainty, and the permitted error limits of test equipment for testing instrument transformers are presented. Finally, an example of an uncertainty budget for a current transformer of the class 0,2 S is given.

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