Current Transformer

Precise contactless DC and AC magnetic sensors are required by car industry, chemical industry, for measurement of power and many other applications. The emphasis is given on current sensors based on magnetic materials, but other methods are also mentioned for ...

This paper presents design and implementation of a mobile embedded system to monitor and record key operation indicators of a distribution transformer like load currents, transformer oil and ambient temperatures. The proposed on-line monitoring system ...

Three phase motor is part of many applications. These motors are widely used in industrial and agriculture area. Traditionally these are either controlled by user manually where protections are mostly not taken care or may be done using isolated unit. In industry, induction motors are used in hazardous area where human presence might be risky. " Motor protection and control unit by wireless media " unit don't require any special consideration while operating. Once user gives Command/instructions, by android application via Wi-Fi then unit automatically turns motor ON/OFF. This unit will have great application for industrial motor interface where maintenance operators need frequent access for motor status and control. Also the majority of Indian population is engaged in agriculture and lives in villages. The key issues faced by an average farmer with irrigation water pumps is water wastage, travelling long distances through difficult terrains just to operate the pumps, encountering snakes and other dangers creatures en-route erratic power supply, motor/starter damage and fuel. Thus, the Motor protection and control unit by wireless media provides a solution for these problems. New Wi-Fi technologies are coming with wider coverage, which can be used for agriculture application.

A test program was completed to measure arc flash incident energy from actual 480-V utility equipment to determine the most appropriate flame resistant clothing for utility workers. The equipment tested included self-contained and CT-rated meters, padmounted transformer secondary cubicles, power panels, and network protectors. Testing was performed to determine the sustainability of low voltage arcs in actual utility equipment, the most appropriate calculation method to predict the measured incident energy, and to identify any key variables that would effect both duration and heat from this type of equipment.

This paper presents a method for the design of
shell-type, single-phase distribution transformers to obtain
the manufacturing specifications. The method is simple, efficient
and accurate. By an exhaustive analysis, it is concluded
that the obtained solution is the global optimum. The following
constraints are imposed: excitation current, no-load
losses, total losses, impedance and efficiency. The methodology
of this paper requires only six input data: transformer
rating, low voltage, high voltage, connection of low-voltage
coil, connection of high-voltage coil, and frequency. These
data are included in the transformer nameplate. In this paper,
the minimization of the following four objective functions
is considered: total owing cost, mass, total losses and material
cost. The consideration of these four objective functions
is implemented automatically by running the optimization
algorithm four times without intervention of a designer. Consequently, transformer manufacturers save design man-hours
and increase capacity. A design example on a 25 kVA transformer
is presented for illustration. The optimized solutions of transformer design are validated with laboratory and process
measurements.

This paper describes the power factor improvement of 3-phase induction motor, as improvement of power factor is necessary for industries & to make power factor as close as unity without facing penalty from electrical distributers. Induction motors are the most widely used electrical motors due to their reliability, low cost and robustness. For industrial and mining applications, 3-phase AC induction motors are the prime movers for the vast majority of machines. At no load induction motor has very low power factor. It improves at increasing load from no load to full load. Power factor improvement is achieved by using proper algorithm with sufficient capacitors are switched on in order to compensate the reactive power. The circuit in this design has been implemented and tested in the laboratory.

The travel and tourism sector has emerged as one of the most important sectors for developing as well as developed countries. Tourism incorporates many of the features of the information society such as globalization, mobility and information richness. People from all nations, social rank, and professions are potential tourists. Tourism links a worldwide supplier community with consumers, equally distributed worldwide.

Aquaculture production has increased rapidly during the last three decades. This is due to increased production of established species as well as a continuous introduction of new species. Productivity growth is the main engine for the increased production in aquaculture, and as the accumulated knowledge is applied to new species and in new regions, production is expected to continue to

This paper presents a multi-band CMOS VCO using a double-tuned, current-driven transformer load. The dual frequency range oscillator is based on enabling/disabling the driving current in the secondary port of the transformer. This approach eliminates the effect of switches connected directly to the VCO tank whose capacitance and on-resistance affect both the tuning range and the phase noise of a

Voltage drop is the most commonly occurred problem in the distribution system due to the constantly increasing demand on the load side of the power system. The voltage dip causes serious damages to the quality of the power in the system. This paper deals with the compensation of voltage dip that occurred in the distribution side of the power system by reconfiguration of load bus in the distribution system. Current transformer senses and pass the signal to the breaker to change the switch for compensation of load demands by continuously cross-checking its rated voltage in the bus of the distribution system. Hence, the voltage drop gets compensated by the continuous reconfiguration of the load bus to match the demand in the load side of the distribution system, hence the power quality is improved in the system. PSCAD tool is used for the simulation purpose. IEEE 9 bus radial distribution system is used as a test bus for this entire simulation carried works.

Due to the current transformation of Central Eastern European (CEE) economies, not very much is known about managerial behaviour during that era. With a view of increasing such an understanding, this paper reports some observations on characteristics of the leadership styles of managers in CEE as experienced by Finnish expatriates. The emerging changes in these styles are also discussed. By reviewing relevant writings and studies, working hypotheses about expected differences between Finnish and CEE managers are formulated. Differences were identified and it was found that typical leadership styles among managers share certain common characteristics in three CEE countries but that the styles have already started to change. In conclusion, the implications of the findings for Western companies and for expatriate managers are discussed.

The authors present a frequency-output fiber-optic current sensor for high-power systems. The sensor exploits the magnetostriction of the ferromagnetic core of a standard current transformer, which is interrogated by a length of single-mode fiber coiled onto it and a Mach-Zehnder interferometer. The deformation of the core due to the magnetic field generated by the current produces a frequency-modulated output signal. The current is obtained from the frequency features of the optical signal, and so the sensor avoids certain shortcomings of other fiber optic current sensors such as light power fluctuations, phase drift, and polarization sensitivity.