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An annual substation equipment failure report says 3/7 capacitive voltage transformer (CVT) got damaged because of ferroresonance overvoltage. The conventional mitigation circuit fails to protect the transformer as the overvoltage may fall in the range between 2 and 4 per unit. It is necessary to develop a device to suppress the overvoltage as well as overcurrent of the CVT. This study aims to propose the suitability of memristor emulator as a mitigation circuit for ferroresonance.

The literature implies that a nonlinear circuit can protect the transformer against ferroresonance. An attempt is made with a memristor emulator using Operational Amplifier (OPAMP) for the mitigation of ferroresonance in a prototype transformer. The circuit is simulated using PSpice and validated for its ideal characteristics using hardware implementation. The nonlinear memductance is designed which is required to mitigate the ferroresonance. The mitigation performance has been compared with conventional method along with fast Fourier transform (FFT) analysis.

While the linear resistor recovers the secondary voltage by 74.1%, the memristor emulator does it by 82.05% during ferroresonance. Also, the total harmonic distortion (THD) of ferroresonance signal found to be 22.06% got improved as 2.56% using memristor emulator.

The suitability of memristor emulator as a mitigation circuit for ferroresonance is proposed in this paper. As ferroresonance occurs in instrument transformers which have extra high voltage (EHV) rated primary windings and (110 V/[110 V/1.732]) rated secondary windings, the mitigation device is proposed to be connected as a nonlinear load across the secondary windings of the transformer. This paper discusses the preliminary work of ferroresonance mitigation in a prototype transformer. The mitigation circuit may have memristor or meminductor for ferroresonance mitigation when they are commercially available in future.

The electronic component-based memristor emulator may not work at 110 V practically as they may be rated at low power. Hence, chemical component-based memristor emulator was developed to do the same. The authors like to clarify that the memristor will be a solution for ferroresonance in future not the memristor emulator circuit.

With the real form of memristor, the transistor world will be replaced by it and may have a revolution in the field of electronics, VLSI, etc. This contribution attempts to project the use of memristor in a smaller scale in high-voltage engineering.

The electronic component-based memristor emulator is proposed as a mitigation circuit for ferroresonance. The hypothesis has been verified successfully in a prototype transformer. Testing circuit of memristor emulator involves transformer, practically. The mitigation performance has been compared with conventional method technically and justified with FFT analysis.

Discusses the 27 papers in ISEF 1999 Proceedings on the subject of electromagnetisms. States the groups of papers cover such subjects within the discipline as: induction machines; reluctance motors; PM motors; transformers and reactors; and special problems and applications. Debates all of these in great detail and itemizes each with greater in‐depth discussion of the various technical applications and areas. Concludes that the recommendations made should be adhered to.

This paper aims to focus on the implementation of the International Electrotechnical Commission (IEC) 61850–9-2 standard based process bus with merging units (MUs) and sampled values (SV) to improve the protection and control systems. The digital process interface is important to be included on the process bus level.

The IEC 61850–9-2 process bus standard is not extensively used in regard to SV when the IEC 61850 standard is implemented by power utilities. Many protection and control intelligent electronic devices (IEDs) are connected to a substation communication network, routers and switches using fibre-optic linked Ethernet. However, inductive current transformers (CTs) and voltage transformers (VTs) secondary circuits are still hardwired to the IEDs. The paper highlight issues with the copper wires for currents signals and how these issues can be eliminated by using the MUs and the SV protocol. The voltage regulator control IED of each transformer is required to regulate the voltage level of the secondary side bus bar it is connected to. All the regulating IEDs of parallel-connected transformers are required to communicate with each other to share information. They collectively control the bus bar voltage depending on the switching configuration of the parallel transformers.

It is shown that process bus information such as the high voltage switchgear status information of primary plant in the yard, can be used to improve the substation protection and control systems. The power transformer protection and voltage regulator control are focused on.

The deliverables of the research work can be applied in: The Centre for Substation Automation and Energy Management systems of the Department of Electrical Engineering, power utilities and other establishments using power systems and digital substations in the electrical supply industry. The research work on the thesis led to the development of a laboratory test-bench where students can learn and understand the basics of the IEC 61850–9-2 SVs principles. The test-bench components such as the IEDs, real-time digital simulator, standalone MUs and Ethernet equipment can be used for future research applications. The test-bench can be used to demonstrate during course work for students at the University, the basics of digital substations using a process bus network with IEDs, MUs and Ethernet equipment.

The research work showed where lab equipment is getting outdated and future equipment will be required for research work in IEC 61850–9-2 process bus.

Power utilities can benefit from implementing the IEC 61850 part 9–2 of the standard and by using MUs and other process interface information in substations. A cost reduction in high voltage equipment, substation installation and commissioning costs and better performance of protection and control system can be achieved.

Problems of correct estimation of metrological characteristics of current transformers based on constructional data and working conditions are of great importance. Applying the commonly known equivalent circuit of the current transformer requires its parameters to be determined correctly. A method for determining the equivalent circuit parameters of a current transformer, based on its field models, is shown in this paper. The results obtained using field computation and real‐life model tests are compared.

The purpose of this paper is to discuss the operation of new generation electromagnetic current-to-voltage transducer. The aim of research was analysis of behaviour of considered current-to-voltage transducers during operation. The main problem was to estimate whether the external fields are able to change the value of the secondary voltage and that the replacement of the casing material by a conductive or ferromagnetic material will increase the immunity of the transducer to external magnetic fields. The immunity of current-to-voltage transducers to the external fields is very important because it influences the proper functioning of the protection system.

The use of analytical methods to assess the influence of external fields was impossible due to the complexity of the geometry. The 3D computations were necessary because of different cross sections of circuit boards at different heights. Therefore the numerical 3D field-and-circuit method based on finite element method was applied. The wide range of dimensions in computation system, ranging from 0.15 mm (print paths) to 0.22 m, made it necessary to use the mesh of millions of elements. The division of this type of system into elements requires a diverse and extremely dense mesh in the area of printed circuits board (PCBs).

The 3D analysis of magnetic field distribution was performed for different external field effect upon a current-to-voltage transducer. The magnetic field distributions and the induced secondary voltage for several different cases were presented. As a conclusion it can be said that in this particular case the magnetic shield is most effective. The influence of external magnetic fields caused by currents passing through the other neighbouring phase bars near are insignificant for the transducer with non-magnetic core.

Commonly used in measuring and protection systems of the transmission lines are induction instrument transformers. The instrument transformers are very precise devices and their errors are counted in tenths of a per cent, and phase displacement of signals in minutes. Especially in HV systems they are very big and their cores are heavy. Replacement of instrument transformers by the current to voltage transducers cooperating with electronic measuring systems will reduce the size and cost of devices.

The requirements set for protective current transformers concern the transformation of currents, with high accuracy, especially at transient states. Therefore magnetic characteristics of their cores should be linear. It causes that cores are large and have some air gaps. Current-to-voltage transducers based on Rogowski coil are particularly suitable for the replacement of the protective current transformers because of their linearity. The traditional technologies used for making Rogowski coil consisted in winding a wire on a non-magnetic carcass. The development of technology has enabled the use of new technologies PCB high density interconnect in the production of Rogowski coil.

Supply chain management.

The case is suitable for post graduates in management, and for those managing small sector supply and manufacturing systems.

ACPL is an organisation which moved from trading to manufacturing a technology product instrument transformers (ITs) for power utility companies for 11 years, competing with the best in industry, reducing internal costs, and modernising the supply chain. ACPL was started as a trading organisation in electrical items in Delhi by Munish Kumar, an engineer by profession in 2001. In 2004 he ventured into manufacturing, which expanded in two locations in Ghaziabad, NCR Delhi. Later his two sons, engineer and management graduate, respectively, joined the organisation. In less than a decade, by 2007, ACPL had grown to be a private limited organisation. ACPL manufactures ITs required by power boards and companies for conversion and usage of high voltage (11 kV/33 kV) transmitted power into 220 V single phase/440 V three phase power. From tender/enquiry through manufacturing to inspection and despatch takes a long supply chain cycle time holding space as well as inventory. An interview with the chairman of ACPL in the case highlights issues affecting its margins and growth. The long process to delivery time may be in vogue in this type of industry but this holds up a huge inventory. The company management has been working to resolve this crisis along with an urgent need to grow in a competitive environment. The problem is being addressed.

This case study should help students to understand the concept of the supply chain and supply cycle, in a manufacturing company in particular. It has been found that students understand the supply chain as part of the marketing function dealing with finished stocks, warehousing and delivery to end customers as per agreements, and arranging payments from customers. The supply chain also deals with in bound materials management. Raw materials planning, purchasing, inventory management are crucial for effective business operations management in any organisation.

Teaching notes are available; please contact your librarian for access.

In the paper, some cases of using HV insulator in SF6 gas medium are discussed. Computations, permitting to optimize the insulation system geometry and to make use of the HV insulator in atypical constructions, were carried out. The equipotential lines and diagrams of the electric field strength, enabling to draw conclusions concerning shapes of constructions are presented.

The year 2013-14 was very significant for Raychem RPG Ltd (RRL) - a joint venture between RPG group, India and TE Connectivity, USA. The sales were looking up and order book was promising. Newly restructured units were working well and business in new segments was picking up. There were several initiatives undertaken by the CEO in last five years of his tenure. His team had achieved the desired stability and turnaround was successful. A high-growth future in a slowing global economic scenario had to be converted into a more profitable opportunity. However, he faced several questions. Was the strategic transformation journey that he embarked on four years ago complete? Could he have done something different? Which were the areas where the next focus should be? Did RRL have the required competences to succeed in those areas? How would RRL manage the changing expectations of the two JV partners?

The purpose of this paper is to consider a constructional solution of the combined instrument transformer: constructed so that the voltage part is a column transformer, which means that the magnetic circuit of it is open and situated into a composite insulator. The aim of this research was to achieve optimal configuration of open magnetic circuit of the column voltage transformer.

The authors made analyses of electromagnetic field distribution and computed the voltage error and phase displacement for many different cases of magnetic circuits of the column voltage transformers. The analyses of the electromagnetic field distribution and computations were carried out using the 3D field‐circuit method based on the finite‐element numerical method. The results were compared with tests of a real‐life model.

The result of research is the selection of the best constructional version of the column voltage transformer; the research also gives some guidelines for design and manufacture of this construction of combined transformers.

The paper is meant for constructors of instrument transformers and presents results of research into new constructional solutions of combined transformer.

Considers the concerns of engineers designing overcurrent protection and measuring systems. Looks at the use of software to determine the instrument security fader with higher accuracy than with traditional calculation methods. An application of a space‐and‐time analysis makes it possible to calculate the peak value of the secondary voltage.