Telephone Interference Research Articles

Perancangan Sistem Informasi Konsultasi Dokter Pada Lapas Narkotika Kelas IIB Muara Sabak

Narcotics Correctional Institutions (Lapas) provide guidance, mental recovery, and behavior for narcotics users and dealers. Apart from that, prisons are also required to maintain the health of their inmates, as in the case study of this research at the narcotics prison class II B Muara Sabak. Health services that have been running so far are still conventional or manual, in which the inmates want to seek treatment and health checks through health workers (nurses) assigned to the prison, but in consultation services to doctors, nurses are always in contact via telephone or doctors can come directly. This is sometimes inconvenient, especially for busy doctors who can't immediately pick up the phone or who have the problem of telephone interference during consultations. For this reason, it is necessary to have a website-based consulting service system that needs to be designed to overcome this problem. The methods used in this research are problem analysis, material collection, system design, and prototypes. This research will produce a prototype of a health service information system and a doctor's consultation in which this system provides consultation services to doctors via chat via an online application system so that doctors can handle problems without having to come in person or via telephone. Consultation records and medical record history will always be stored in a database that makes it easier for officers to trace back, and health services for prison members can be handled quickly and effectively.
 Keywords : prison, consultation, doctor, online

Telephone Interference From Solar PV Switching

The emergence of solar Photovoltaic (PV) generation has been one of the biggest changes in the Power Grid in the past decade. Such generation plants are generally inverter based and these devices are known sources of harmonics of the fundamental frequency and ‘supraharmonics’ (distortion in the frequency range 2 to 150 kHz). It has long been theorized that due to factors such as the frequency response of service transformers that interface solar PV plants to the grid, impedance of the power system at the point of common coupling and the impedance of devices connected near solar inverters, supraharmonics frequencies are localized and generally do not couple to the grid. Exceptions to this general hypothesis have been reported in Europe, where supraharmonics from PV and wind power plants have been shown to couple to the local three-phase three wire Medium Voltage (MV) system. This paper shows that in three-phase four wire multi-point grounded MV systems, such as the ones used in the United States (U.S.), application of conventional grounding schemes to PV plants can lead to the unintended consequence of coupling of supraharmonics to the grid through the neutral conductor and ground circuit. It describes a case study in which supraharmonics due to inverter switching led to telephone interference for customers located around a solar PV plant. To determine the mechanism by which the supraharmonics frequencies were coupling to the grid, an investigation of the emission from the plant was performed using conducted as well as radiated measurements. The novel setup used for performing these radiated measurements, the unique underlying mechanism by which inverter switching frequencies coupled to the grid and the lessons learned in this process regarding solar PV grounding and installation practices are described in this paper.

Use of multiple methods to measure impact of a centralized call center on academic health system community pharmacies.

The process and methods used in an impact assessment of a centralized pharmacy call center on community pharmacy employee patient safety climate perceptions, telephone distractions/interruptions, and prescription filling efficiency are described. A broad-based team designed a multi-faceted, pre-post call center implementation analysis that included multiple change assessment measures. First, yearly administration of the Agency for Healthcare Research and Quality Community Pharmacy Survey on Patient Safety Culture was used to assess patient safety climate based on employee perceptions of a safe working environment and potential for errors due to interruptions and distractions. Evaluative measures of staff workload that assessed telephone interference with prescription filling activities pre and 3 months post implementation included (1) the NASA Task Load Index, (2) multi-tasking observations through shadowing of pharmacists and technicians to count number of interruptions/distractions per prescription "touched," and (3) self-reported work sampling to assess proportional time estimates of clinical, professional, and technical activities. Finally, pharmacy efficiency and prescription filling capacity were assessed using operational measures (prescriptions filled, patients served, phone call volume changes, prescription rework counting). Data analysis included summary statistics, Student's t-test, and chi-square analysis, as appropriate, in addition to assessing convergence and agreement among measures. Every evaluative method showed a positive outcome from call center implementation, although individual pharmacies may have accrued greater benefit from call reduction than others. Multiple analysis methods can be used to evaluate the impact of workflow changes.

A Distributed Filtering Scheme to Mitigate Harmonics in Residential Distribution Systems

This paper presents a novel scheme to mitigate harmonic distortions in modern residential distribution systems. The scheme deploys multiple low-voltage filters in randomly selected locations of a distribution system. The main challenges of such a distributed filtering scheme, cost of installation and hardware, are solved through an innovative filter configuration and installation concept, namely, the filter is a 240 V device that can be easily plugged into the sockets of utility revenue meters. Analytical, simulation, and economic studies have been conducted to understand the filter design parameters, performance characteristics, and cost implications. As an example application, the scheme is evaluated for mitigating an actual harmonic-caused telephone interference problem. The results show that the proposed scheme can be a promising option to reduce the harmonic distortions in selected areas of a distribution system.

Reducing the effects of harmonics on the electrical power systems with passive filters

Users or customers of the electrical power systems must pay attention to some factors during operation and design of these systems in order to operate safe and in desired format. One of these factors is harmonic caused by non-linear elements determining the quality of the power as a parameter. Some harmful effects of harmonics can be listed as; disruption of control devices, explode of capacitors, overload of transformations and additional losses in rotating machines, motors, and the occurrence of extra noise to motors and other elements, to cause telephone interference, parallel and serial resonance frequency. The most important and useful method of eliminating or reducing of harmonics is using harmonic filters. In this study, two different factory in the city of Van located at the east of the Turkey are examined in detail with a variety of different dates by Zera MT310's power analyzer measurements (instantaneous electrical values, harmonics, current and voltage waveforms, etc.). With these measurements, some power lacks of quality are determined and examined. After this process, single-tuned passive filter is designed by using Matlab/Simulink software for these factories.

A Technique to Mitigate Zero-Sequence Harmonics in Power Distribution Systems

This paper presents a technique to mitigate zero-sequence harmonics in power distribution systems. The method is based on the concept of passive zero-sequence harmonic filters. However, its basic configuration has been expanded to create a double-tuned filtering feature. This feature makes it possible to trap two harmonics with one filter and is especially attractive in solving harmonic-caused telephone interference problems. Furthermore, this paper has shown that common utility service transformers can be used to construct the filter. As a result, a practical and low-cost solution to mitigating zero-sequence harmonics has been found. A method for sizing and loading assessment of filters has also been developed. As an example application, the proposed filter package has been applied to mitigate a telephone interference problem. Issues, such as filter location, the number of filters required, and the effectiveness of filtering harmonics produced by distributed residential loads have been investigated. The results show that the proposed filter is a very promising technique to reduce zero-sequence harmonics in primary power distribution systems.

Cellular Telephone Interference With Medical Equipment

Cellular Telephone Interference With Medical Equipment

Cellular Telephone Interference With Medical Equipment

To assess the potential electromagnetic interference (EMI) effects that new or current-generation cellular telephones have on medical devices. For this study, performed at the Mayo Clinic in Rochester, Minn, between March 9, 2004, and April 24, 2004, we tested 16 different medical devices with 6 cellular telephones to assess the potential for EMI. Two of the medical devices were tested with both new and old interface modules. The 6 cellular telephones chosen represent the different cellular technology protocols in use: Code Division Multiple Access (2 models), Global System for Mobile communications, Integrated Digital Enhanced Network, Time Division Multiple Access, and analog. The cellular telephones were tested when operating at or near their maximum power output. The medical devices, connected to clinical simulators during testing, were monitored by observing the device displays and alarms. Of 510 tests performed, the incidence of clinically important interference was 1.2%; EMI was Induced in 108 tests (21.2%). Interference occurred in 7 (44%) of the 16 devices tested. Cellular telephones can interfere with medical equipment. Technology changes in both cellular telephones and medical equipment may continue to mitigate or may worsen clinically relevant interference. Compared with cellular telephones tested in previous studies, those currently in use must be closer to medical devices before any interference is noticed. However, periodic testing of cellular telephones to determine their effects on medical equipment will be required.

Digital mobile telephones and interference of ophthalmic equipment

To assess the effect of mobile telephone electromagnetic interference on electronic ophthalmic equipment. Prospective audit with mobile telephones placed at distances of 3 m, 1 m, and 30 cm from, and in contact with, electronic ophthalmic equipment. Any interruption or cessation of the function of the ophthalmic device was assessed with the mobile telephones in standby, and in dialling or receiving modes. Any alterations of displayed digital figures or numbers were also assessed. A total of 23 electronic ophthalmic devices in two hospital ophthalmology outpatient departments were evaluated. All six mobile telephones used, and 22 (95.7%) of the 23 ophthalmic equipment evaluated had the Conformité Européene (CE) mark. No device showed any interruption or cessation of function. There were no alterations of displayed digital figures or numbers. The only effect of any kind was found with four instruments (1 non-CE marked), where there was temporary flickering on the screen, and only occurred when the mobile telephones were dialling or receiving at a distance of 30 cm or less from the instruments. This study shows that among the electronic ophthalmic devices tested, none suffered failure or interruption of function, from mobile telephone interference. Although not comprehensive for all ophthalmic equipment, the results question the need for a complete ban of mobile telephones in ophthalmic departments. It highlights the need for a controlled, objectively measured study of the clinically relevant effects of mobile telephones in the ophthalmology outpatient setting.

HIA—focused on positive results

HIA—focused on positive results

Development of hearing-aid near-field EMI testing

With the introduction of digital cellular telephone technology, cellular telephone interference to hearing aids is now a noticeable problem for both hearing-impaired digital cellular phone users and bystanders. Previously, bystander hearing-aid immunity levels (far field) were defined by the IEC committee and are contained in the current IEC 118-13 hearing-aid electromagnetic immunity standard. With the realization that an up-scaled far-field test would be insufficient to provide an accurate correlation of digital cellular telephone usability, the ANSI C63.19 working group developed a near-field test procedure using calibrated dipole antennas. This paper discusses the development of near-field testing, broken down in the following topics: (1) digital cellular phone interference and spectral properties; (2) rf interference coupling into the hearing aid; (3) far-field testing and rationalization behind the use of 1-kHz 80% AM modulation to quantitatively determine hearing-aid immunity characteristics; (4) near-field simulation using dipoles and antenna calibration; (5) near-field repeatability testing; and (6) preliminary results of near-field hearing-aid interference measurements. The result of these developments has led directly to the formulation of the near-field test procedure described in Sec. 5 of the currently developing ANSI C63.19 standard.

Harmonic resonance on parallel high voltage transmission lines

Harmonic resonance has been observed, measured and modeled on parallel 500-kV lines that are about one wavelength at 2100 Hz, the 35th harmonic. A seemingly small harmonic injection at one location on the system causes significant problems some distance away such as telephone interference.

HVDC transmission and the environment

The increased use of electrical systems has led to significant changes in the electromagnetic environment (RFI, TVI, telephone interference, carrier-frequency interference). The extent to which large electrical systems, such as HVDC transmission networks, impinge on the environment has become a topical and even controversial issue. This article takes a look at some of the more important technical considerations as well as the consequences HVDC transmission systems have on human beings and the environment in general. The article also considers briefly what measures can minimise the detrimental effects of HVDC transmission including acoustic noise reduction.

A three-pulse model of DC side harmonic flow in HVDC systems

A model for analysis of DC side harmonics in HVDC systems is proposed. The model includes the stray capacitances of converter transformers and bushings and represents the 12-pulse converter as four three-pulse harmonic voltage sources. The appearance of ground-mode triplen harmonics of troublesome magnitude in pole and electrode lines, as noted in recent site measurements, is explained, as is the increase in magnitude of the characteristic 12-pulse harmonics. The consequences for DC design and the specification of telephone interference criteria are also discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Telephone Interference Criteria for HVDC Transmission Lines

The telephone interference caused by a transmission line is primarily characterized by the equivalent line disturbance current defined as: l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</sub> =√Σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> · I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> where C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> = C-message weighting factor for the n:th harmonic l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> = residual line current of n:th harmonic For many HVdc lines, particularly in North America, this current has been required to be <270 mA. During the last few years, however, values as low as 100 mA have even been specified by some utilities. Since the cost for installation of dc filters in the converter stations becomes high and very progressive if the equivalent line disturbance current has to be limited to less than about 1 A, it is very important that the specified value reflects the actual need from a telephone interference standpoint. The object of the report is to identify the maximum tolerable equivalent disturbance current for transmission lines. This is done by means of a combination of calculations and measurements in which different key parameters are scanned and evaluated. Based on a general calculation of coupling impedance versus soil resistivity and frequency, specific data are defined for a typical "worst case" coupling between a HV line and a telephone system in a suburban area. Disturbance current criteria for a dc line are given in the report based on a maximum noise metallic voltage at a telephone set of 17 dBrnC (OdBrnC = 24.5 μV across 600 ohm) and a circuit balance of 60 dBrnC.

Telephone interference criteria for HVDC transmission lines

The coupling between a transmission line and telephone cables is calculated on a general basis. Based on field measurements of the current harmonic spectrum from a modern 12-pulse HVDC (high-voltage direct current) converter, the ratio between disturbance current and resulting noise level in a telephone system is established. Disturbance current limitation criteria are identified based on tolerable noise level and assumptions regarding typical worst-case coupling conditions in a suburban area between a transmission line and a telephone system. It is concluded that disturbance current criteria as currently specified for some HVDC lines are substantially more stringent than corresponding criteria for both distribution lines and HVAC (high-voltage alternating current) lines.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Impact of stray capacitance on HVDC harmonics

Stray capacitances inherent to HVDC converters are shown to cause all triplen harmonics to appear on the DC side. In particular, odd-triplen harmonics are produced which in a bipolar DC system will cause ground-mode simulation of the DC transmission line. The levels predicted by simulation can be large enough to cause significant telephone interference if the DC filtering, including both pole and neutral buses, is not designed to accommodate these harmonics. Field experience provides qualitative support for this theory.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Measurement of harmonic currents and evaluation of the DC filter performance of the New England-Hydro-Quebec Phase I HVDC project

Measurements were conducted to determine the cause of increased telephone interference and to evaluate the DC filter performance. The measurements revealed unexpected high levels of three-pulse harmonic currents in the DC pole conductors. The cause is attributed to imbalances within the six-pulse bridges caused by the converter transformer and valve stray capacitances to ground. The conventional model of the converter power circuit used as the basis for the DC filter design does not reproduce the measured three-pulse harmonics.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

DC System Resonance Analysis

DC filters and dc smoothing reactors are primarily designed to meet performance requirements with regard to telephone interference levels and commutation failure frequency. Other factors, however, place constraints on the size of the dc filter capacitance and the smoothing reactor inductance. The principal constraint is the avoidance of resonance conditions on the dc side at a low order harmonic of the commutating voltage. This paper discusses the factors which must be considered when analyzing dc side resonance. Specific considerations for the Intermountain Power Project are given.

Distribution Feeder Harmonic Study Methodology

The procedures for performing harmonic studies are becoming more important to distribution engineering as more harmonic-producing loads are added to distribution feeders. This paper summarizes the methodology used to perform these studies and describes some of the tools used in the analysis. A typical example illustrates the methodology for a feeder that has a telephone interference problem.