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In this paper, we present a summary of lightning protection measures aimed at securing a more reliable power supply for a telecom building. Based on an analysis of the entry paths of lightning surges into telecom building, we implemented lightning protection measures for the power receiving facilities by strengthening the equipment's tolerance to overvoltage surges. This was achieved by using a multistage...
In February 2014, the NTT Group officially announced that it has launched a high voltage direct current (HVDC) (380-VDC) with a 4-MW-scale power supply system for the Tokyo metropolitan area. Activities, such as international standardization, has led to the commercial commencement of a full-fledged 380-VDC power supply system, demonstration projects, and technology development, which took more than...
We discuss the advantage of highly efficient and reliable higher-voltage direct current (HVDC) power feeding systems and the standardization activities for the power interface conditions in ICT equipment. With the recent spread of Internet services, the power consumption of ICT services is increasing annually. Many data center servicers want to decrease the power consumption of ICT equipment, cooling...
This paper describes the configurations of semiconductor circuit breakers we developed for higher-voltage direct-current (HVDC) power feeding systems. Semiconductor breakers have some merits. The shutdown parts of the breakers are compact and can be controlled remotely. In addition, they do not need to be replaced after shutting down a short circuit. When semiconductor breaker shutdown overcurrent...
We present a quantitative analysis of the benefits of the 380 VDC power distribution system compared to the current −48-VDC power supply system. The analysis is based on models of typical distribution configurations in global telecommunication sites and takes into account codes, regulations, and practices for wiring and voltage drop comparison between centralized/decentralized 48- and 380-VDC. In...
400VDC is becoming a new voltage interface for telecommunication buildings and data centers as well as for ICT equipment. 400VDC interface covers applications for up to 400VDC with a typical nominal voltage of 380VDC. Key drivers for utilizing a higher DC voltage are overall efficiency and reliability gains vs present solutions. However, introduction of a new 400VDC interface brings up some questions...
This paper describes a semiconductor breaker for higher-voltage direct-current (HVDC) power feeding systems. To reduce energy consumption of ICT devices, one effective measure is to manage their power use. To manage the power of individual ICT devices, circuit breakers, which turn ICT device power on and off, must be compact and remote-controllable. Because feeding voltage fluctuations, which occur...
Reducing the feeding loss of information and communications technology equipment, such as servers and routers, is very effective for reducing the total power consumption in data centers and telecommunication buildings. In this paper, the structure and function of a higher-voltage direct-current (HVDC) power feeding system prototype is presented. This system was developed to reduce power delivery and...
In this paper, two simple electronically-steered on-board satellite-tracking circularly polarized stacked-type dual-band patch array antennas for mobile satellite communications are numerically investigated. The configurations of the novel antennas are shown and their performances are discussed. The first model is fed by probes while the second one is fed by microstrip line. The gain obtained for...
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