Imagine building a 4,100 km fiber optics network across Argentina and Chile, through the Andes. Think about the ruggedness of the terrain, the cold temperature, the high altitude and the lack of an AC electrical grid to power the network in those remote locations. These were some of the challenges Silica Networks faced in implementing the first phase of construction of their fiber optics network. When searching for a company to provide highly reliable primary power for those remote sites, Silica Networks selected Ormat Energy Converters.
Silica Networks, a partnership between three significant industry players: National Grid, a UK power transmission company, Williams Communications, an international provider of telecommunications services and products for the carrier marketplace; and Manquehue Net, a Chilean voice and data provider, was formed in response to the tremendous demand for communications services in Latin America. Silica Networks promotes high-speed transmission, high reliability and network security as the main offerings to its customers. The reliability of the power supply in these remote, inhospitable areas of the network, is particularly critical to their success in the market, making the Ormat Energy Converters (OEC) a logical choice for the power solution in remote sites.
With more than 3,000 OECs deployed around the world, to power telecommunications sites, gas pipelines and offshore production platforms and more than l00 million hours of field operation, Ormat's OECs have demonstrated impressive reliability in the harshest conditions with minimal maintenance. For example, since 1976 over 100 OECs have been operating effectively on the Alaskan pipeline project.
The OEC, a closed
cycle vapor turbo generator (CCVT), utilizes a hermetically sealed Rankine
cycle generating set that contains only one smoothly rotating part, the
shaft on which the turbine wheel, brushless alternator rotor and return
feed pump are mounted. The turbo alternator shaft is supported by working
fluid film bearings, which eliminate any metal-to-metal contact, resulting
in years of trouble-free operation. The system can be run with different
fuels, since the fluid cycle is closed, and requires only the application
of external heat, for continuous, maintenance free applications. In this
application, natural gas is used in Chile and LPG in Argentina. 
The OECs installed in this network supply 2,500 watts of 48 VDC, to power the electronic telecommunications equipment. In addition, the OEC provides non-electric heating for the equipment shelter. The heating system is essential for reliable system performance since, in the winter months, temperatures inside the shelter can reach far below 0°C) and cause the electronic communications equipment to malfunction. The Ormat OEC provides a non-electric heating system based on co-generation from unused heat. This heating system keeps the equipment in the shelter above 5°C without consuming any electricity, thus assuring a safe temperature for the electronic equipment.
The first stage of this project was completed and commissioned in May 2001, with dual, redundant Ormat OECs powering two sites in the Andes at 8,000 feet elevation. Ormat's Energy Converters were selected to power these remote sites because of their proven capability to provide highly reliable power, supporting Silica Network's promise to its customer to deliver highly reliable communications services.
For
more information contact Sharon Sugarek at
214-221-9398, ssugarek@orbitpower.com or www.ormat.com
Ormat Energy Converter System Description
The Ormat Energy Converter (OEC), a closed cycle vapor turbogenerator (CCVT), is a fully integrated and tested power system developed for remote applications. Basically a self-contained power package, it consists of a combustion system, a vapor generator, a turboalternator, an air-cooled condenser, a rectifier, and alarms and controls, housed in a shelter. The system can provide from 200 to 3,000 Watts of filtered DC power on a continuous basis for up to 20 years with minimal maintenance.
The OEC system utilizes a hermetically sealed Rankine cycle generating set which contains only one smoothly rotating part, the shaft on which the turbine wheel, brushless alternator rotor and return feed pump are mounted. The turbo alternator shaft is supported by working fluid film bearings, which eliminate any metal-to-metal contact, resulting in years of trouble-free operation.
The fluid cycle is closed and requires only the application of external heat, for continuous, maintenance-free applications. Because of its purity, liquefied petroleum gas is a desirable fuel for typical telecommunications applications. However the system may be fueled by natural gas, kerosene, jet fuel or diesel fuel as well.
Ormat Energy Converter System Operation
The burner heats the organic fluid in the vapor generator-some of it vaporizes and expands through a turbine wheel thereby producing shaft power to drive the alternator the vapor then passes into a condenser where it is cooled and is condensed back into the liquid state. The liquid passes back into the vapor generator, cooling the alternator on its way and lubricating the bearings. The cycle continues as long as heat is applied to the vapor generator. Because the liquid/vapor stainless steel canister is sealed, none of the organic fluid is lost in the process. Furthermore, the working fluid is totally immune to climatic conditions outside the sealed canister.
The turboalternator produces three-phase AC power, which is rectified and filtered. The standard output is 24 or 48 volts DC although other DC voltages and auxiliary AC can be made available.
The system is controlled by a digital turbine control unit, with safety controls to protect against any abnormalities, including overheating. Because of the low operating pressure and temperature of the system, personnel safety is assured.
OEC Applications and Experience
OECs have been deployed in a wide variety of applications: Since 1970, hundreds on OEC units have been deployed to power microwave networks for ENTEL and Telefonica Argentina. Today most of these units are still in operation from central Argentina to Tierra del Fuego.