Telecommunications Station

Wireless communications are becoming dominant worldwide, including in developed countries where a lined commimication infrastructure is well established. In many developing countries, many families do not install lined phones at all, and people use cell phones exclusively for communication. 

Wireless communications are made available by telecommunications stations (i.e., transceiver stations or cell towers). There are about 5 million such stations worldwide. By the end of 2011, China itself had about one 

Example Voltages Used to Start and Stop a Fuel Cell System 

DC buss voltage -53.5 This is a common preset IX buss voltage when there is grid power. 

FC startup voltage -49.5 When the DC buss voltage drops to this preset value, the fuel cell system starts. 

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Telecommunication stations based in non-interconnected to the grid areas are a promising market segment for autonomous hydrogen power systems. The power demand of such stations ranges from some Watts in the case of minimal stations to 10 kW for mobile-phone relay stations. In telecommunication applications only DC loads are usually served by the installed power system. 

Several sites built to house telecommunication stations, where the antennas, satellite aerials, and all the equipment required for the broadcasting of signals are located on... 

The DC load of telecommunications stations typically ranges from less than 1 kW to more than 5 kW. In China, most of the stations have a DC load of around 2 kW. For these kinds of loads, fuel cell systems with air-cooled stacks are the preferred choice. 

Figures 5.8 and 5.9 show the discharging processes of the 53 V/40 Ah and 53 V/10 Ah battery bank at 2350 and 2300 W constant power output with discharge rates at 1.25 and 5 C, respectively. The voltage of the 40 Ah battery bank was around 47 V, above the load s lower voltage limit of 43 V for telecommunications stations. However, the voltage of the 10 Ah battery bank dropped to 41.9 V in one minute, so this battery bank could not provide power by itself to the load with the lower input voltage limit of 43 V. Since the 10 Ah battery bank worked together with the stack to supply power to the load through the system s main DC-DC converter, tests showed that it was enough.

Eight-hour test of a 2.5 kW fuel cell system in a telecommunications station. Courtesy of Wuhan Intepower Fuel Cells. 

Table 5.5 lists the key characteristics of the fuel cell system. The RS232 communication port is used because this is the type of port used by telecommunications stations. Some warning actions had two sets of values one set for less-severe situations that triggers the warning alarm but does not shut down the fuel cell system the other set is for more severe situations that trigger the warning alarm and shut down the fuel cell system. If the fuel cell system is not able to shut down when the severe values are reached, the fuel cell system or the load it powers can be damaged. 

The fuel cell system was trial tested in a telecommunications station located in Beijing. Figure 5.32 is a picture after the fuel cell and the H2 systems were installed. The H2 system contained four 35 MPa, 30-liter reinforced cylinders, shown as an inset in the figure. When two cylinders were empty, they could be replaced while the other two supplied H2 to the fuel cell system. The... 

With impressed current installations supervised by technical telecommunications, it is sufficient to carry out operational control annually [17]. With gas pipeline grids, it is advisable to build in inspection instruments in the control installations or connecting stations since connection with the telecommunication system is possible. 

Another important area of application is the use of small power units as backup power in situations of sudden loss of grid power because of natural or technical problems. Such backup units are extremely important to those consumers who cannot tolerate power interruptions. This is the case for various stationary telecommunications installations (for instance, receivers, transmitters, relay stations, signal amplifiers). Ofher users who can use unifs of fhis fype are surgery wards in hospitals, computer units in traffic control, financial insfifufions, and emergency lighting systems in public... 

Speaking of military fuel cell applications, we must first point out the following. Most versions of fuel cell-based power plants are of ambivalent utility they are just as good for civil as for military purposes. Thus, the stationary power plants of different sizes used for unintermptible emergency power supplies for military objects such as forts, command centers, radar stations, and the like do not differ in any way from similar power plants for civil use in hospitals, telecommunications installations, computer centers of banks, and so on. Power plants for automotive land and water-bound means of transport are equally good for civil and for military vehicles. This is true, even more directly, for power sources intended to supply portable equipment. A lower volume and weight of all equipment carried by soldiers in combat (e.g., as a means of communication, as a means of orientation, as night-vision devices) is a very important point for land forces. 

Telecommunications terminal equipment and satellite earth station equipment 98/13/EEC 11/6/1992 or 5/1/1995... 

Cell Phones. The telecommunications tool used the world over is the cell phone. A cell phone system employs a series of cells, about ten square miles in size. Each cell site, or base station, is equipped with a tower and an antenna and serves subscribers only within its bounds. A cell phone moving from one cell to another will change operating frequencies automatically to conform with the frequencies assigned to the acljacent cell. This scheme makes it possible to reuse frequencies over and over again as the user moves across the country. 

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