scholarly journals Optimised calibration programmes for comparators for instrument transformers

2021 ◽  
Vol 88 (2) ◽  
pp. 122-131
Author(s):  
Christian Mester
Keyword(s):  
Experimental Study ◽  
Operating Principle ◽  
Device Under Test ◽  
Operating Range ◽  
Ratio Error ◽  
Phase Displacement ◽  
Instrument Transformers ◽  
Instrument Transformer ◽  
Method Of Measurement

Abstract Traditionally, instrument transformers are calibrated using bridges. By definition, bridges use the null method of measurement. The traditional calibration programme for instrument transformer bridges characterise namely this null measurement. Many new commercial comparators for instrument transformer use a very different method. They sample the secondary signals of reference and device under test (dut) transformer independently. Based on the samples, magnitude and phase of both signals are determined. Ratio error and phase displacement are calculated. Consequently, the significance of their calibration using the traditional calibration programme is limited. Moreover, the operating range of modern comparators is much larger than that of bridges. The additional versatility cannot be used without an adapted calibration programme. This article analyses the calibration programmes for both technologies. An experimental study confirms both the suitability of the new calibration programme and the need to chose the calibration programme depending on the technology of the device to be calibrated. The conclusion is very general and applies to all measurement problems where an operating principle is replaced by another – when changing the operating principle, it is important to check the calibration programme and adapt it if necessary.

Highly Accurate Calibration System for Electronic Instrument Transformers

2011 ◽  
Vol 18 (2) ◽  
pp. 315-322 ◽  
Author(s):  
Yue Tong ◽  
Guoxiong Ye ◽  
Keqin Guo ◽  
Hongbin Li
Keyword(s):  
Low Cost ◽  
Phase Error ◽  
Electronic Instrument ◽  
Calibration System ◽  
Ratio Error ◽  
Asynchronous Sampling ◽  
Instrument Transformers ◽  
Convolution Window ◽  
Instrument Transformer ◽  
Electronic Current Transformers

Highly Accurate Calibration System for Electronic Instrument Transformers A high accurate electronic instrument transformer calibration system is introduced in this paper. The system uses the fourth-order convolution window algorithm for the error calculation method. Compared with Fast Fourier Transform, which is recommended by standard IEC-60044-8 (Electronic current transformers), it has higher accuracy. The relative measuring errors caused by asynchronous sampling could be reduced effectively without any special hardware technique adopted. The results show that the ratio error caused by asynchronous sampling can be reduced to 10-4, and the phase error can be reduced to 10-3 degrees when the deviation of frequency is within ±0.5 Hz. The present method of measurement processing is achieved by a high-accuracy USB multifunction data acquisition (DAQ) card and virtual measurement devices, with low cost, short exploitation period and high stability.

Measurement of Ratio Error and Phase Displacement of DC Tolerant Current Transformers

2007 ◽  
Vol 5 (1) ◽  
pp. 289-292 ◽  
Author(s):  
Pavel Mlejnek ◽  
Petr Kašpar ◽  
Karel Draxler
Keyword(s):  
Current Transformers ◽  
Ratio Error ◽  
Phase Displacement

Study on Precision Selection of Instrument Transformer and its Calibration for Automatic Test System

2013 ◽  
Vol 333-335 ◽  
pp. 2461-2464
Author(s):  
Bo Wang ◽  
Hai Sen Zhao ◽  
Shou Jun Lian
Keyword(s):  
Test System ◽  
Testing System ◽  
Automatic Test ◽  
Measuring Point ◽  
Automatic Test System ◽  
Instrument Transformers ◽  
Instrument Transformer ◽  
Transformer Ratio ◽  
The Cost ◽  
Selection Of

System accuracy is an important assessment indicator for automatic test system, which is influenced by many factors such as instrument, person, and environment. The paper takes a set of automatic motor testing system for an example, the mathematic relationship between the system accuracy and the precision of instrument transformers was analyzed, which also provides a theoretical reference for the precision selection of instrument transformer when the system accuracy was known. Some improved measures such as the selection of measuring point and the calibration of transformer ratio and phase angle are put forward. Testing results verified its simplicity and efficiency, besides the novelty above, the paper also provides a new idea to improve the system accuracy of constructed test platforms without increasing the cost for exchanging a matched transformer.

scholarly journals Experimental Study on Active Control of Surge in a Centrifugal Compression System

2000 ◽  
Vol 6 (5) ◽  
pp. 383-392
Author(s):  
Nie Chaoqun ◽  
Chen Jingyi ◽  
Chen Naixing
Keyword(s):  
Experimental Study ◽  
Control System ◽  
Active Control ◽  
Nonlinear Interaction ◽  
Compression System ◽  
Operating Range ◽  
Stable Operating ◽  
Control Scheme ◽  
On Line

An experimental study has been carried out on the active control of surge in a centrifugal compression system. With a computerized on-line control scheme, the surge phenomenon is suppressed and the stable operating range of the system is extended. In order to design the active control scheme and choose the desired parameters of the control system inputs, special emphases have been placed on the development of surge inception and the nonlinear interaction between the system and the actuator. By use of the method designed in the present work, the results of active control onsurge have been demonstrated for the different B parameters, different prescribed criteria and different control frequencies.

scholarly journals To the Problem of Protection of Medium Voltage Instrument Transformers with Fuses: Analytical Research

2021 ◽  
Vol 60 (3) ◽  
pp. 92-102
Author(s):  
Yevgen Bajda ◽  
Oleksandr Grechko ◽  
Viktor Buhaichuk ◽  
Robert Knápek
Keyword(s):  
Analytical Study ◽  
Promising Direction ◽  
Medium Voltage ◽  
Advantages And Disadvantages ◽  
Instrument Transformers ◽  
Effective Level ◽  
Instrument Transformer ◽  
Analytical Research ◽  
Further Development

Introduction. In the medium voltage power grid of 6–35 kV, there is a problem of protecting voltage instrument transformers. This is due to the insufficiently effective level of their protection with fuses. Recently, there have been more and more reports of accidents associated with the failure of voltage instrument transformers not only in Ukraine, but also abroad. The issue of conducting an analytical study of the problem of protection of medium voltage instrument transformers by fuses is relevant. Goal. Investigation of designs and characteristics of fuses for medium voltage instrument transformers to improve the efficiency of their protection. Results. The article shows that protection of medium voltage instrument transformers with epoxy insulation is often provided by fuses, in which the nominal current of the fuse-link is significantly higher than the maximum permissible long-term current of the primary winding of the instrument transformer. A comparative analysis of the current values of the primary winding of medium voltage instrument transformers with the values of the rated currents of the fuse-links of fuses of various manufacturers presented on the Ukrainian market is carried out. The design features and technical characteristics of fuses for medium voltage instrument transformers have been investigated in order to increase the efficiency of their protection. The advantages and disadvantages of the designs of fuses from various manufacturers have been investigated and it has been established that the design of fuses requires further improvement in order to increase the efficiency of protection of medium voltage instrument transformers. Discussion and prospects for further development. Since in Ukraine, the need for fuses to protect medium voltage instrument transformers is provided mainly by supplies abroad, a promising direction for further development in this direction is the creation of a domestic competitive design of a fuse and its introduction into production.

scholarly journals Measuring the Voltage Dependence of Current Transformers

2020 ◽  
Author(s):  
Helko van den Brom ◽  
Ronald van Leeuwen ◽  
Gert Rietveld ◽  
Dennis Hoogenboom
Keyword(s):  
Leakage Current ◽  
High Voltage ◽  
Voltage Dependence ◽  
Current Transformers ◽  
Ratio Error ◽  
Phase Displacement ◽  
Hv Cable

A setup has been developed to determine the voltage dependence of the ratio error and phase displacement of current transformers (CTs) used for medium- or high-voltage (HV) applications. A shielded HV cable is used to protect the reference CT for the voltage applied to the CT under test. As a first step, a method was developed to determine and correct for the effect of the leakage current through this cable on the ratio error and phase displacement of the reference CT for voltages up to 24 kV.

Condition Assessment of High Voltage Instrument Transformer Using Partial Discharge Analysis

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
Mohd Aizam Talib ◽  
Abu Sufian Abu Bakar Abu Bakar ◽  
S. Gobi Kannan
Keyword(s):  
High Voltage ◽  
Diagnostic Tool ◽  
Economic Activity ◽  
Field Measurement ◽  
Laboratory Experiments ◽  
Partial Discharge ◽  
Incipient Faults ◽  
Instrument Transformers ◽  
Customer Dissatisfaction ◽  
Instrument Transformer

Determining the incipient faults in high voltage apparatus is important because failure without warning can result in damage to adjacent equipment, personnel injures, customer dissatisfaction and disruption to economic activity. The failure of several high voltage instrument transformers during in-service prompted Tenaga Nasional Berhad (TNB) to identify more effective diagnostic tool to predict insulation breakdowns. The viability of partial discharge (PD) measurements in the field on instrument transformers is investigated. This paper presents the results of partial discharge tests that have been carried out under laboratory experiments and field measurement on high voltage instrument transformers.

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