Jul 17 2011

Uninterruptible Power Systems

Published by genportadministrator at %I:%M %p under Fuel Cell System

Over 50% of failures for critical loads are due to the electrical supply and the hourly cost of downtime for the corresponding applications is generally very high. It is therefore vital for the modern economy, which is increasingly dependent on digital technologies, to solve the problems affecting the quality and the availability of the power supplied by the distribution system when it is intended for sensitive loads.

Digital equipment (computers, telecom systems, instruments, etc.) use microprocessors that operate at frequencies of several mega or even giga Hertz, i.e. they carry out millions or even billions of operations per second. A disturbance in the electrical supply lasting just a few milliseconds can affect thousands or millions of basic operations. The result may be malfunctions and loss of data with dangerous (e.g. airports, hospitals) or costlyconsequences (e.g. loss of production).

More than 35 years after they first appeared, Uninterruptible Power Systems (UPSs) now represent more than 95% of back up power interfaces sold and over 98% for sensitive IT and electronics applications. Acting as an interface between the mains and sensitive applications, UPSs supply the load with continuous, high quality electrical power regardless of the status of the mains.

UPSs deliver a dependable supply voltage free from all mains disturbances, within tolerances compatible with the requirements of sensitive electronic devices. UPS can also provide this dependable voltage independently by means of a power source (battery) which is generally sufficient to ensure the safety of individuals and the installation.

UPSs are currently made up of three main sub-assemblies :

  • a rectifier-charger to transform the alternating current into direct current and charge the battery;
  • a set of batteries (generally lead-acid type) enabling energy to be stored and instantly recovered as required over a 5 to 30 minutes period, or even more;
  • a static converter to convert this direct voltage into an alternating voltage that is perfectly regulated and filtered in terms of voltage and/or frequency.

Use of Batteries lead-acid has several relevant limitation, health and environmental problem:

  • Low energy density – poor weight-to-energy ratio limits
  • Cannot be stored in a discharged condition
  • Allows only a limited number of full discharge cycles – well suited for standby applications that require only occasional deep discharges.
  • Lead content and electrolyte make the battery environmentally unfriendly.
  • Transportation restrictions on flooded lead acid – there are environmental concerns regarding spillage.
  • Thermal runaway can occur if improperly charged
  • Elevated temperature reduces longevity

Due to these relevant problems, Fuel Cells are becoming the technology choice for Uninterruptible Power Systems (UPS),  and PEMFC are being taken up by end-users in the telecoms, utilities, IT and other industry sectors.

The potential to move into formal system implementation in the field is driven by the Total Cost of Ownership gains resulting from the substitution of batteries by fuel cells.

These gains can be very significant in areas where grids are unstable (Asia, Africa, India) but are still significant in Europe where grid networks are quite stable.

Power sources  like G300 HFC and G300 HPS are ideal substitute technologies to lead-acid based UPS.

Quick start up, no environmental and acoustic emission, reliability, shock resistance, light weight are key advantages enabling Genport power source to fully satisfy requirements of small portable UPS, utilized in field surgical hospitals, mobile army medical corps, yachts, tactical telecoms units.

Power, Current and Voltage profile of G300 HFC. Voltage is stable (not decreasing as battery) while current is dynamically changing following the load demand.


G300 HFC powers a mobile communication system

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