Increasing reliability and availability of telecom sites by using CCVT power solutions

Abstract

In today's competitive environment, telecom operators are continuously looking on one hand to optimize their revenues and reduce their capital and operating expenditures, and on the other hand to keep supplying uninterruptible and continuous services with the highest quality of service (QoS) and maximum availability. For many operators selecting the appropriate power solution remains a fundamental and a key factor for achieving their operating goals and objectives. When evaluating several different types of alternative power solutions, the criteria for selection may vary from one operator to another. Nevertheless, it seems that more and more operators are reaching the conclusion that proven technology, proven reliability and availability, and low equipment life cycle costs are the leading criteria for making their power selection. Over the last 38 years, the closed cycle vapor turbogenerator (CCVT) with a proven track record of thousands of successful installations worldwide, has gained the reputation as one of the most extremely reliable and proven technologies for continuous and uninterruptible power supply in the range of 200 to 6000 Watts for various off-grid and grid-connected wireline and wireless telecom applications. The CCVT system utilizes a hermetically sealed Rankine cycle generating set consisting of an external combustion system, a vapor generator, a turboalternator, an air-cooled condenser, a rectifier, and a control and monitoring module, all housed in a weather-proof self-contained shelter/enclosure. The high reliability of the CCVT technology is achieved by its simplicity. It contains only one moving part, the shaft on which the turbine wheel and brushless alternator rotor are mounted. The turbo alternator shaft is supported by working fluid film hydrodynamic bearings, which eliminate any metal-to-metal contact and any consequent wearing, resulting in years of trouble-free reliable operation. The CCVT is designed to operate at nominal power in temperature ranges of -60/spl deg/C to +45/spl deg/C (-76/spl deg/F to +113/spl deg/F), altitude of up to 4,500 m (15,000 feet) ASL, wind velocity of 120 km/hr (75 mile/hr) with acceptable gusts of up to 160 km/hr (100 mile/hr). The CCVT can be fuelled either by liquid fuel (diesel, kerosene, alcohol, etc.) or by gas fuel (LPG, natural gas, methane, etc.). The normal output voltage is 24 or 48 VDC. The life expectancy of the CCVT power solution is over 20 years, with proven turbine MTBF (mean time between failures) of over 200,000 hours. The CCVT technology appears to be the ideal power solution for many telecom applications in which extremely reliable operation, maximum availability, minimal maintenance and low life cycle cost are essential. The following paper describes the experience gained with the CCVT by increasing the reliability and availability of telecom sites, many of them in very harsh environmental conditions.