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Comparison of Static and Rotary UPS

Hitec Diesel Rotary UPS versus Static UPS

There are a number of key financial, operational and physical criteria thatshould be considered when choosing a UPS System and to assist in thisdecision making process we have detailed below a comparison highlightingthe principle differences between the Hitec Diesel Rotary UPS System and anequivalent Diesel Generator/Static UPS System.

1.0 Space

The Hitec Diesel Rotary UPS System is a complete and self containedUPS and Standby Power Supply System and as such replaces thefollowing discrete components required for a Static UPS System:

i) Standby Diesel Generatorii) Static UPS Moduleiii) Standby Batteriesiv) Air conditioning module (Essential to maintain the correct

ambient temperature of between 20 to 25 degreesC for batteryoperation)

v) Mains Failure Panelvi) Output Paralleling and Bypass Switchgear Panel (Necessary for

multi-module operation)vii) Power factor correction equipment

viii) Mains filtering to achieve G5/3 compliance

When taking into account all of the items of equipment required for aStatic UPS System it can be clearly demonstrated that the Hitec DieselRotary UPS System requires in the order of 40 to 60% less space.

2.0 Weight

As well as requiring less space, the Hitec Diesel Rotary UPS Systemwill offer a weight reduction of up to 30% over that for the combinedtotal weight of all the elements necessary for a Static UPS System.

3.0 Maintenance required over a 20 year period

3.1 Static UPS System

The ultimate lifespan of a well maintained Static UPS Module isaround 10 to 12years. So, over a 20year maintenance periodthis element of Static UPS System will need to be completelyreplaced at least once.

In addition to the Static UPS Module the Batteries, despitehaving a design lifespan of up to 10years, will need to be

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Comparison of Static and Rotary UPS

replaced at least three times. This is due to extensive fieldexperience, which shows that in order to prevent failureBatteries should be replaced at least every 6 to 7years.

3.2 Hitec Diesel Rotary UPS System

In contrast to a Static UPS System, the Hitec Diesel Rotary UPSSystem combined with a standard maintenance regime can beexpected to have an operating lifespan well in excess of 20years.

Consequently, a comparison of the respective maintenance costs forthe two UPS systems proves that, over a 20year maintenance period,the Hitec Diesel Rotary System will be significantly less costly to

maintain than an equivalent Static UPS System.

4.0 Effic iency and Running Costs

The Hitec Diesel Rotary UPS System has a proven efficiency ofbetween 96 to 97%, compared to that of Static UPS Systems with theirmaximum achievable efficiency of between 92 to 94%. The differencein these efficiency figures, of between 3 to 4%, will result in significantnet annual savings; typically for a 1MVA System the saving would be inthe order of 14,000 and for a 2MVA System it would be in the order of24,000.

Additionally, the cost savings for utilising a Hitec Diesel Rotary UPSSystem will be further increased when the inefficiencies of theadditional Mains Filtering and Power Factor Correction equipment areadded to the annual running cost of the Static UPS System.

5.0 Input Power Factor Correction

The Hitec Diesel Rotary UPS System, by virtue of the uniquecombination of its Synchronous Generator and Coupling Choke,

provides natural Power Factor Correction for the load. Typically theInput Power Factor will be held at 0.98pf for all downstream loadconditions.

6.0 Input/Output Harmonic Voltage Distor tion

The unique combination of the Synchronous Generator and CouplingChoke also provides a high attenuation path for all extraneousharmonics emanating from the load. Typically the Input HarmonicVoltage Distortion will be less than 3%.

7.0 Ambient conditions

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The Hitec Diesel Rotary UPS System is designed to function in

ambient temperatures between 0 and 40 degrees C without the needfor additional cooling.

8.0 Reliability

With field experience gained over 30 years and with an installed baseof 1117 modules supporting a total critical load in excess of 720MVA,we can demonstrate though our predicted Mean Time Between Failurefigures (MTBFs) that Hitec Diesel Rotary UPS Systems are in excessof 10 times more reliable than the equivalent Diesel Generator/StaticUPS solution.

9.0 Fault Clearing

The Hitec Diesel Rotary UPS System will deliver a peak fault currentunder short-circuit conditions of 15 times the full load current of themodule. Therefore, a 1MVA module will deliver a peak short-circuitfault current of 21kA.

A Static UPS System will deliver a peak fault current under short-circuitconditions of around 1.5 times the full load current of the unit.Therefore, a 1MVA Static UPS Module will deliver a peak short-circuitfault current of 2.1kA. This level of fault current will be insufficient toclear the fault, so in order to clear the fault Static UPS Systems musttransfer its load to bypass and allow the upstream supply to providesufficient fault current.

This comparison shows that the Hitec Diesel Rotary UPS System offerssignificant and tangible benefits over a Static UPS System. Should yourequire any further information or a more detailed comparison for specificapplications please do not hesitate to contact us on 01926 484 535 or visit ourwebsite: www.hitecups.com