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An indoor distributed antenna system (DAS) is a network of small antennas that prevents isolated spots of poor coverage inside densely populated indoor spaces. In addition to an antenna, a DAS node can include equipment such as amplifiers, remote radio heads, signal converters and power supplies that propagate, process or control the communications signals transmitted and received through the DAS...
During the last decade, being involved in preparation of organizations and companies for disastrous and crisis situations, I was revealed to the lack of knowledge and awareness Engineers have in the use and even existence of standards and regulations in their fields. During academic studies a lot of mathematics and physics are supplied to the engineering students enabling them to start their professional...
At current, the communications industry is still at the fast-growing stage. A large number of new base stations and equipment rooms will surely bring an enormous growth in energy consumption. As the enterprises need to maintain a sustainable development and the operators have to face the financial and social pressures from high energy consumption, it is very urgent for the operators to build green...
Off-grid Radio Base Stations are currently powered by Diesel generators. Nevertheless an alternative can be possible improving three critical aspects of the problem: efficiency, costs and environmental impact. In order to address the problem Telecom adopted the choice to host a solution based on renewable energy sources and fuel cells. The solution chosen is named “FCpoweredRBS” meaning fuel cell...
With today's new battery technology and power hungry devices that may need many hours of emergency battery backup, there is the danger of short circuit currents reaching more than 100kA and exceeding the short circuit current ratings of existing DC fuses. Until manufacturers design, test and certify DC fuses with higher short circuit current rating, excessive short circuit currents pose a danger to...
We are currently investigating the specifications of the architecture and control method of a DC power system with photovoltaics and fuel cells that achieves longer power-supply time with limited stockpiling-energy without grid power. For this paper, we focused on the case in which electric power needs to be constantly supplied to a load but photovoltaic power generation is unstable. We applied (1)...
This paper presents the design and experimental performance of a compact, 50W/in3 (3kW/liter), and 96.2% peak efficiency 3.5kW single phase rectifier for telecommunication application. The rectifier is composed of two stages connected in series. The bridgeless PFC boost rectifier with bidirectional switch has less forward diode voltage drop than conventional technologies. The DC-DC converter is based...
With the rising rate of electricity prices and peak demand surcharges contributing to increased operational expenses for today's telecommunications (Telecom) companies, the utilization of existing assets can play a key role in the management of these costs. Through the intelligent management of backup power sources, such as DC power plants with existing battery backup systems and AC UPS systems, Telecom...
In the field such as telecommunications, UPS, finance, electric power and so on, the VRLA batteries are usually used in a series connection, but when there exists a faulty or several faulty batteries, the performance/life of the battery bank will deteriorate seriously to endanger the safety of power supply. After inspecting and analyzing the problem occurred of the battery backup time shortage in...
In this paper, an energy storage system (ESS) with a photovoltaic (PV) generation and an on-line uninterruptible power supply (UPS) functions is proposed. The proposed system is composed of an inverter, a bidirectional converter, a PV converter, and a battery converter. The inverter provides a regulated sinusoidal output voltage to the load like the on-line UPS. The bidirectional converter operates...
When stationary lithium-ion batteries are used as a telecommunications backup power supply system, they need to be linked in series to achieve −48 V, and serially-connected lines must be connected in parallel to ensure capacity. To improve the reliability of a system, we must reduce the number of parallel lines. Therefore, we have developed a large capacity 200 Ah battery. We have also improved the...
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...
This paper presents a high power density DC-DC converter for electric propulsion of micro and nanosatellites. The front end of the proposed topology consists of a full-bridge LLC resonant converter. LLC resonant converter is particularly chosen since this resonant tank yields significant voltage boost without addition of external components to the resonant tank while operating in the lagging current...
We describe how inrush current flowing into an electromagnetic interference (EMI) filter when ICT equipment is connected to an HVDC system affects the operation of other currently connected ICT equipment. When ICT equipment is connected to an HVDC system, inrush current flows to the EMI filter of newly connected ICT equipment. The inrush current causes voltage oscillation at the input of other (previously...
The interchange of power between power supply systems is proposed as a way to reduce the storage battery capacity required to compensate imbalances in power generation and demand. The results of simulations for calculating the expected reduction in required battery capacity in a constructed power supply system are also reported.
With the wide application of clean energy, the technology of energy storage has been greatly developed. Conventionally we use single way of energy storage like lithium battery or lead acid battery. However, except advantages, all these ways of energy storage have their limitation. Take lithium battery for example, it has quick responding time, but it is restricted by time and space. For lead acid...
An Uninterrupted Power Supply (UPS) is typically used to supply power to IT equipment in data centers so critical telecommunications services are not disrupted in the event of a power outage. When a data center loses power, the IT equipment continues to operate on emergency UPS power, but the temperature inside the data center begins to rise because the air conditions stop running. Modern IT equipment...
For connecting HV DC grids either to AC grids or to DC sources, power electronic converters (AC/DC and DC/DC topologies) in the power range from a few hundred kilowatts up to the MW range are needed. Typical requirements are: • High conversion efficiencies, even on low load conditions • High reliability and redundancy, service under system operation • Low harmonic grid impact, provision of grid support...
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