INTELEC - Twentieth International Telecommunications Energy Conference (Cat. No.98CH36263)

A novel topology for an AC/DC converter is proposed. An input bias capacitor connected in series with the AC mains is employed, which together with an appropriate control allows for removal of the rectification diode bridge. A bidirectional DC/DC Cuk converter is then employed to produce a closely sinusoidal input current while maintaining the bias capacitor voltage such that the sum of line and b... View full abstract»

Common-mode transients can be induced when protection devices such as fuses or circuit breakers blow due to faults that occur between the feeder and ground. Such transient voltages can be substantially larger than the powering voltage and could lead to breakdown of equipment. The mechanisms that cause these transients and a method for limiting the transients to safe levels are described using expe... View full abstract»

It is important to optimise the power system architecture because it affects critical parameters (cost, reliability, size and consumption) of the whole telecommunications system. However, the selection of the best option is complex because there are a lot of parameters involved in the selection. In this article we analyse how all these parameters affect the overall system and present a tool that c... View full abstract»

This paper examines a constant frequency quasiresonant buck converter controlled by PWM. Converter components are selected such that it operates inherently (without any control) in a constant, maximum power mode over a wide range of the load current. This mode keeps the conduction loss low and in combination with the ZCS for the active devices provides high power conversion efficiency. A complete ... View full abstract»

A new approach to the analysis of battery aging is presented. This new method takes into account the temperature fluctuations experienced by batteries in the field. It can be used not only to predict battery life for a new product, but also can be a helpful tool in the development of new telecommunication network powering strategies View full abstract»

From the environmental point-of view, low power consumption and low noise have been required in recent years and a new soft switch-mode power supply which has been developed to meet these two requirements is presented in this paper. The noise level of this new switch-mode power supply is lower than Class-B of CISPR by 30 db or more and the leakage current which tends to be increased in a low-noise... View full abstract»

This paper presents an unavilability evaluation method of power supply systems for power utility telecommunications and evaluation results using field data. Telecommunication systems in a power utility system have a numerical target of unavailability to be satisfied because they play an important role in power system protection relaying. Recently, switching-type equipment and VRLA batteries have b... View full abstract»

A new control method of a resonant DC/DC power converter with a Class DE inverter and Class E rectifier is proposed. One can easily regulate the output voltage or power with eliminating the diode voltage pulse on the rectifier at a constant rate while the operating frequency is fixed. In this paper, the authors give an analysis, design equations and experimental results for the circuit. In the opt... View full abstract»

The reliability performance of a DC UPS system having redundant (n+1) rectifiers and battery back-up of several hours can be theoretically very high. Emergence of digitalized implementation of supervisory and control functions can significantly reduce or even totally destroy the naturally high reliability performance. It has turned out in many field occasions that the reliability performance of a ... View full abstract»

This paper examines an implementation of the average current mode control (ACMC) in a frequency controlled series resonant converter used in a telecommunication rectifier. This control mode provides very fast output overcurrent protection and improves reliability of the series resonant converter. In addition it improves significantly the dynamic response of the output voltage control loop to meet ... View full abstract»

In this paper, the main principles and the general structure of battery monitoring and management systems (BMS) are explained. Furthermore, a newly developed, highly accurate and inexpensive data acquisition system for BMS is presented. The modular measuring system consists of two different types of monitoring units, a battery block-voltage monitoring unit and a battery current and temperature mon... View full abstract»

A new valve regulated battery range in gel technology for telecom application was developed. The 12 V monoblocks can be installed in 19" racks with 300 mm depth. Analysis of failures occurred in the past led to improvements of design, process and materials, which have been implemented in the new range. The charging regime was optimized to ensure high state of charge over the whole temperature rang... View full abstract»

As digital loop carrier (DLC) architectures carry fiber deeper and deeper into the local loop to satisfy ever-increasing bandwidth demands, techniques and costs for powering there architectures are sometimes ignored. Here, the authors examine the costs associated with delivering power to these O/Es or ONUs as different quantities of ONUs are powered from a single power node. The conclusions show t... View full abstract»

The International Lead and Zinc Research Organization (ILZRO), in cooperation with Sandia National Laboratories, has initiated a multi-phase project to characterize relationships between VRLA technologies, service conditions, and failure modes; establish the degree of correlation between specific operating procedures and premature capacity loss (PCL); identify operating procedures that mitigate PC... View full abstract»

A new type of monobloc battery was launched onto the telecommunications market in 1993 for 24" deep, 23" telecomms racks as the first of a series of second generation products designed from the authors' experience and user experience of earlier types originally launched in 1982. This paper describes the advantages compared with more conventional products. These include a long narrow footprint for ... View full abstract»

NTT's telecom buildings are equipped with emergency engine generators for use in the event an outage occurs in the commercial power supply. To ensure they are in proper operating condition, these engine generators must be tested to inspect their starting capability at regular intervals of one to three months. This paper discusses the results of verification tests conducted on pseudo-malfunctions u... View full abstract»

This paper proposes the analysis and design of lossless, passive soft switching methods for PWM converters. The emphasis of the design and analysis is for PWM converters that use nonminimum voltage stress (non-MVS) circuit cells to provide soft switching. PWM converters with non-MVS circuit cells have several distinct advantages over converters that use minimum voltage stress (MVS) cells. With the... View full abstract»

In the telecommunication application there is a tendency to reduce the backup times from mainly 3 to 8 hours down to 30 minutes to 1 hour. To fulfil the requirement for long lasting batteries in this application field the battery must be at least a ten years system with the ability to supply high currents on short term discharges. The combination of service life >10 years and high rate discharg... View full abstract»

This paper describes the escalating Internet development, which is characterised by the integration of telecommunications and data communications. An obvious example is Internet telephony through packet switching. Carrying voice traffic means intensified demands on power supplies of the Internet equipment, to meet public demand for an ever-functioning service. With data traffic, a small number of ... View full abstract»

This paper presents a number of case studies and technical arguments which support the concept that the -48 volt rail is the source of choice for computer equipment deployed in the telecommunications network View full abstract»

In this paper, a model of a telecom power supply including batteries is presented. The transfer functions of the system are derived to study the stability. A PID-controller is designed to stabilize the system without batteries and tuned in two control modes. When the batteries are added to the system, the stability is maintained. Simulink is shown to be a suitable simulation tool used in validatin... View full abstract»

The digitally controlled DC-DC power converter has an advantage of high reliability, high controllability and high flexibility. A new digital controller for PWM and/or PFM controlled switching DC-DC power converters is presented, which is versatile in general use such as switching frequency from 20 kHz to 500 kHz, hard-switching and soft-switching View full abstract»

Valve regulated lead acid (VRLA) batteries have been used in telecommunication power systems for over a decade and with them has followed demands on the handling of batteries at low voltages. Devices connected in series to the system are often incorporated to disconnect the batteries from the load in the event of a near deep discharge. This paper covers the design considerations for one such devic... View full abstract»