High Voltage Feeder Research Articles

Exposure to natural stray currents of low voltage affects the behaviour and some stress biomarkers of weaned piglets

With the modernisation of pig breeding facilities, pigs may be exposed to both on-farm and off-farm sources of stray voltages. Data from ruminant species suggest that exposition to stray voltages may be a source of stress and impair animal welfare, but data are scarce for pigs. The aim of this study was to evaluate the impact of stray currents of voltages under 0.5 Volts in pig housing on piglet behaviours and some biomarkers after weaning. Two replicates of 820 piglets were reared in a farm naturally exposed to stray voltage for seven weeks. The difference in electrical potential between the floor and each drinker and feeder was measured every two weeks. Piglets exposed to high-voltage drinkers (HVD > 125 mV) spent more time orally manipulating pen mates (P = 0.0031). They also spent more time lying inactive with open eyes (P = 0.0027) and less time nosing pen mates (P = 0.043), but these effects were influenced by the voltage in feeders (P = 0.0021 and P = 0.024, respectively). Piglets exposed to high-voltage feeders (HVF > 50 mV) spent less time lying with their eyes closed (P = 0.024) and more time aggressing pen mates (P = 0.0081). Fifty days after entering the farm, blood hydroperoxide concentration was higher in piglets exposed to HVD (P = 0.039). The increase in socio-negative behaviours and oxidative stress in pigs exposed to stray voltages in pig housing suggested that stray voltages might have moderate detrimental consequences for piglets in post-weaning facilities.

Elastic topological interface states and voltage feeder by breaking inversion symmetry on thin plates

The rapid progress in the engineering of topological edge/interface states has attracted considerable interest in both photonic and phononic systems originating from their electronic equivalent systems. However, most classical wave types, such as electromagnetic/acoustic waves in topological engineering, are described by two-dimensional (2D) partial differential equations (PDEs), which are not suitable for thin plate motions. We present a 1D elastic topological interface state induced by symmetry breaking to bridge a knowledge gap in 4D PDE, particularly for flexural waves on thin-plate frameworks. We also leverage the localized state at the interface for energy harvesting, which can provide a sufficiently high voltage feeder by piezoelectric effects.

Euler's Formula-Based Stability Analysis for Wideband Harmonic Resonances

During propagation along medium- or high-voltage feeders, the currents generated by distributed generation power plants (DGPP) can exhibit harmonic tendencies to deteriorate over wide frequency ranges. These phenomena are construed as wideband harmonic resonances. Although the shapes of these harmonic resonances can be delineated by using the Π-type feeder model with hyperbolic functions, the involved sinh or cosh terms can hinder researchers from obtaining the relative stability of the systems by applying classic stability criteria. To this end, we proposed transforming the hyperbolic functions via Euler's formula for complex numbers. These transformations enable us to evaluate the relative stability of the system in terms of poles and zeros in the complex plane. We find that: first, the underlying causes of the wideband harmonic resonances correlate with the motion patterns of the eigenvalues on the complex plane; second, a recommended coordinated damper restricts the motion ranges of the eigenvalues as the system frequency varies, and this restriction guarantees the invariability of the time-domain performance of the systems. Simulation, experimental results, and a case study verify the applicability of the proposed stability-analysis method.

Two-Stage Load Profiling of HV Feeders of a Distribution System

This paper describes a two-stage unsupervised clustering based on the g-Means approach, which can employ any partitional or crisp clustering algorithm for load profiling of high-voltage (HV) feeders of a distribution system. The methodology proposed can evaluate number of clusters and its respective members from input data. The outcome of g-Means is dependent on a significance level— $\alpha$ . This paper is based on feeder loading data, which are recorded at a transformer secondary at a distribution substation. Real-life active power data of 33-kV feeders acquired through existing supervisory control and data acquisition (SCADA) system of Central Indian state distribution company have been taken as a case study, as it is being processed for the first time, and hence, no prima facie information regarding the number of clusters or classes was available. The first stage entails checking for the randomness in daily load patterns and to extract month-wise working day (weekday) and nonworking day (holidays/Sundays) patterns. The second stage is based on this outcome, where clustering is performed to group similar patterns into clusters to generate month-wise “typical monthly load profiles”. The results are acceptable and are validated by using appropriate validity indices.

Application of let‐through energy to back‐up over‐current protection on high‐voltage feeders

Let-through energy (LTE) refers to the I 2 t or Joule energy that a conductor is exposed to during a fault on the feeder. This energy is influenced by the magnitude of the fault current and time it takes for the protection system to clear the fault. If the LTE exceeds the conductor thermal energy limit, the conductor will get damaged. This concept of LTE evaluation is applied to the inverse definite minimum time (IDMT) current based back-up protection elements on a multisource high-voltage feeder in a hypothetical and actual network. Another method to calculate the relay operating time for IDMT relays was developed based on an average disk speed of electromechanical over-current relay and the proportionality of its speed to the magnitude of the fault current. This method was incorporated into a software application to generate results. These results allow the user to evaluate the conductor LTE exposure, total fault time exposure, the effect of instantaneous fault clearing and the application of auto-reclose cycles. An energy-area evaluation was applied to quantify and evaluate small protection settings changes. The conclusion is that LTE analysis on back-up protection should be considered for high-voltage feeders to ensure that the conductors are protected.

Particle electrification in an apparatus with a draft tube operating in a fast circulating dilute spout-fluid bed regime

The intensity of the electrostatic charge accumulated during the flow of Cellets® particles in a modified Wurster apparatus is investigated in terms of the bed mass, and the initial moisture and velocity of the spouting gas. Particle electrification is proportional to the increase in the velocity of the spouting gas, which is connected with a higher velocity of the cores and the strength of their impact on the walls of the device. The presence of moisture in the bed facilitates electrification, but does not affect circulation, since moisture simultaneously lowers the bed resistance and reduces the relaxation time of particles, leading to rapid discharging if brought into contact with the conducting elements of the apparatus. Therefore, with regard to classic dry-powder coating, the velocity of the spouting gas should be minimized to ensure good circulation, with the particle moisture held at the maximum level admissible for a given product. The investigations show that a unique construction of the apparatus, which brings about an intense natural electrification of the cores, makes it suitable for the electrostatic dry-coating process by means of a high-voltage feeder with the controlled charging of coating powder in the spray nozzle.

Continuous Remote Online Partial Discharge Monitoring of HV Ex/ATEX Motors in the Oil and Gas Industry

This paper presents results from the continued application of a new technique for the remote online partial discharge (OLPD) testing and monitoring of in-service high-voltage (HV) explosive atmosphere (Ex)/atmosphere-explosive (ATEX) motors operating in hazardous gas zones. The technique employs high-current wideband high-frequency current transformer sensors located remotely from the motor under test, at the switchboard end of the HV feeder cable. Significant cost and operational benefits can be gained from this remote monitoring technique as the stator winding condition of these motors can be monitored without having to enter the hazardous gas (Ex/ATEX) zone. The work described in this paper is a continuation of that carried out by the same authors, as reported at the 2012 IEEE Petroleum and Chemical Industry Technical Conference, and includes the development of proposed condition guidelines for assessing the condition of the stator winding insulation systems of large populations of aged HV motors, based on an OLPD “league-table” database. Two case studies are presented wherein the HV stator insulation condition and reliability of in-service motors, operating in hazardous gas zones, and HV generators were assessed using both online and offline partial discharge (PD) testing and monitoring techniques. The case studies emphasize the importance of carrying out extended continuous OLPD monitoring of in-service rotating HV machines to detect underlying trends in PD activity over time. This paper concludes with how condition monitoring data can support reliability-centered maintenance and condition-based management regimes.

Forced Cooling of High-Voltage Feeders

Oil-filled cables, pipe-type, and self-contained lend themselves easily to forced cooling by oil circulation, with return The éither by an auxiliary pipe or another identical feeder.

Line-to-Line Faults on A-C Network Feeders

This paper deals with the magnitude of currents in a secondary a-c network due to a line-to-line fault on the high-voltage feeder, and gives the analysis of the double-unbalance circuit resulting when a network protector fails to open during such a fault, and one of the protector fuses blows. Results of field tests made on an actual network are included.

Line-to-line faults on A-C network feeders

This paper deals with the magnitude of currents in a secondary a-c network due to a line-to-line fault on the high-voltage feeder, and gives the analysis of the double-unbalance circuit resulting when a network protector fails to open during such a fault, and one of the protector fuses blows. Results of field tests made on an actual network are included.

A New Hydro-Electric Power Scheme in Sweden

A FULL description of the hydro-electric power scheme at Krangede, Sweden, which has been in operation for six months, is given in the A sea Journal of May and June, published by the Asea Company of Vasteras. Krangede is situated in about lat. 63° N. at the site of a natural fall on the lower part of the Indalsalven, an important river in the Jamtland district of Sweden draining a large area containing many lakes and extending back to the Norwegian borders. The link with the power station lies well up in 'Norrland', and in the south consists of a high-voltage feeder carried direct down to a main substation at Horndal in South Dalecarlia. It is thus within convenient range of Stockholm and is in touch with the large supply networks of central and southern Sweden.

Evolution of the automatic network relay

Low voltage a-c. networks are coming into use as a means of providing a source of power having the dependability of the Edison d-c. network, and at the same time having the efficiency which can be obtained by supplying power from high voltage feeders with transformers located near the point of utilization. As in the case of d-c. networks, it is assumed that all trouble on the network itself will be burned clear without seriously interfering with any of the service. In case of trouble on a primary feeder or in one of its transformers, however, it is necessary to disconnect the feeder from the system. The a-c. network unit has been developed to connect these transformers to the network, and the “brains” of this unit, which is the automatic network relay, is described in this paper. This relay not only opens the network breaker whenever there is trouble in any of the high tension equipment or when the power feeds back into the high tension feeder but also recloses the breaker when conditions are restored to normal and the feeder is in condition to supply power to the network. The difficulties which were encountered and the relay characteristics necessary to overcome them are explained briefly. The first installation of network units was made in April 1922 on single-phase, three-wire and two-phase, three-wire networks fed by three-phase, 2750-volt primary feeders. Since that time numerous improvements have been made and new designs created to extend the field of application, but the same general scheme of operation has been retained. The automatic network relay is now past the experimental stage, approximately 1000 of them having been in service for some time. The probable future development of the network relay based upon operating experience to date is pointed out. Attention is called to the close relation existing between the operating characteristics of the automatic network relay and the characteristics of the system on which it is to be installed.

Evolution of the Automatic Network Relay

Low-vottage a-c. networks are coming into use as a means of providing a source of power having the dependability of the Edison d-c. network, and at the same time having the efficiency which can be obtained by supplying power from high voltage feeders with transformers located near the point of utilization. As in the case of d-c. networks, it is assumed that all trouble on the network itself will be burned clear without seriously interfering with any of the service. In case of trouble on a primary feeder or in one of its transformers, however, it is necessary to disconnect the feeder from the system. The a-c. network unit has been developed to connect these transformers to the network, and the ``brains'' of this unit, which is the automatic network relay, is described in this paper. This relay not only opens the network breaker whenever there is trouble in any of the high-tension equipment or when the power feeds back into the high-tension feeder but also recloses the breaker when conditions are restored to normal and the feeder is in condition to supply power to the network. The difficulties which were encountered and the relay characteristics necessary to overcome them are explained briefly. The first installation of network units was made in April 1922 on single-phase, three-wire and two-phase, three-wire networks fed by three-phase, 2750-volt primary feeders.

Underground alternating-current network: Distribution for central station systems

1. Certain experimental arrangements for an underground alternating current distribution system are covered in the paper. 2. Low costs and characteristics satisfactory for general utilization of alternating current are contrasted with difficulty of obtaining reliability. The advantage of adopting system characteristics which will make each service suitable for lighting, appliances, and motors is indicated. There is described experience with a combined light and power network on one set of mains. Effect of voltage variation on incandescent lamp illumination is discussed. An appendix covers tests on this subject. 3. Reliability in service of standard distribution materials is considered. Tests on cables are described which indicate that for underground distribution conditions, low-voltage cables will eliminate arcing faults while high-voltage cable will not do so. An appendix of arcing tests is attached. 4. Certain factors are discussed relative to size of mains and location of transformers necessary to make the low voltage network clear its own faults. 5. There is a description of an experimental system consisting of several radial high-voltage feeders, the distribution transformers of all these being connected on the low-voltage side to a common low-voltage cable network. 6. The reactance of the transformer circuits is almost three times that of standard distribution transformers. 7. The only protective devices used are automatic circuit breakers installed in the low-voltage cables between the distribution transformers and the network. The switches open on a reversal of energy from the network and close when the transformers are in a condition to supply power to the network. The devices are sensitive enough to open on transformer magnetization energy. 8. Great reliability is obtained for the network as a switch failure an a high-voltage fault is the equivalent of a short-circuit on the secondary network. 9. Ability to switch automatically all transformers by controlling the supply end of the feeder to which they are connected allows a higher all-day efficiency due to the saving of iron loss at periods of light load. This feature also makes it easy to work on high-voltage equipment. 10. A description of the equipment used in this experimental installation and operating results of switch equipment from date of installation in April 1922 to March 1924 are given. 11. It is believed that with low-voltage a-c. underground networks arranged as described, the reliability is the same as the reliability of the sources supplying the various radial high-voltage feeders. The possibility in the future of a protected network arrangement of the supply system is mentioned.

Underground Alternating Current Network Distribution for Central Station Systems

1. Certain experimental arrangements for an underground alternating current distribution system are covered in the paper. 2. Low costs and characteristics satisfactory for general utilization of alternating current are contrasted with difficulty of obtaining reliability. The advantage of adopting system characteristics which will make each service suitable for lighting, appliances, and motors is indicated. There is described experience with a combined light and power network on one set of mains. Effect of voltage variation on incandescent lamp illumination is discussed. An appendix covers tests on this subject. 3. Reliability in service of standard distribution materials is considered. Tests on cables are described which indicate that for underground distribution conditions, low-voltage cables will eliminate arcing faults while high-voltage cables will not do so. An appendix of arcing tests is attached. 4. Certain factors are discussed relative to size of mains and location of transformers necessary to make the low voltage network clear its own faults. 5. There is a description of an experimental system consisting of several radial high-voltage feeders, the distribution transformers of all these being connected on the low-voltage side to a common low-voltage cable network. 6. The reactance of the transformer circuits is almost three times that of standard distribution transformers. 7. The only protective devices used are automatic circuit breakers installed in the low-voltage cables between the distribution transformers and the network.