Here’s a nice article extolling the use of online double conversion UPS Systems for hospital laboratory applications:
http://www.laboratoryequipment.com/article-sh-reliable-test-results-1009.aspx
We couldn’t agree more.
Laboratory Equipment needs clean power to operate effectively, and this comes from being supplied by a good quality sine-wave power waveform at all times. If you actually read through on the article above you will see an image of a “standard generator output”. Don’t be fooled by this. Generators are never as bad as this – ever. However there is a degree of switching transients, power glitches and frequency variations that can cause havoc with lab equipment (so much so that I’ve known hospital labs to routinely unplug equipment during generator testing – so what will they do when the generator kicks in for real?). Depending upon the generator used and connected loads, the output from the generator can become distorted however, and this is where the online UPS will correct this. Other technologies cannot. I include in this galvanically isolated products that are based on line interactive technology. They cannot do anything about distorted waveforms except drop to battery and go dead a few minutes later.
Another issue that is technically incorrect is the use of galvanic isolation to correct stray earth currents. Since in most galvanically isolated equipment the earth is connected straight through, any current that is flowing will still flow, if the load is galvanically isolated or not. What galvanic isolation does do, is remove any neutral-earth voltage that may exist if the electrical infrastructure is poor or the line is long with heavy load equipment sharing it.
Our recommendations therefore, are for online double conversion for all laboratory products and there’s no need for galvanic isolation meaning smaller, lighter and ultimately cheaper products can be used instead.
