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Thursday, October 27
PQT 14
TVSS/Surge Suppression & Conditioning 2
2:45 pm-4:45 pm
Transient voltages are, perhaps, the most misunderstood and underestimated threats to “Mission Critical” facilities. They can also be the most devastating. In this session we will look at the impact that Transients can have on your critical systems, discuss mitigation techniques and introduce some new concepts. We’ll look at the other side of Transients: Current Surges.
Facility Managers sleep easily at night because they believe that they are protected from such heinous events. But maybe they shouldn’t. Every facility in the world is subject to the devastating effects of Voltage fluctuations. We tend to think that only those who are located in a high lightning strike zone are susceptible. Think again. Spikes, noise, sags and surges can be imposed on the grid from something as simple as the arc welder in your neighbor’s garage, or self inflicted due to equipment in your own facility. Therefore, this session is a must for every Facility Manager.
And if you don’t sleep easy tonight, we’re sorry, but it’s for your own good! Some day you’ll thank me for this. Honest.
Paper Presentations
Current Surges: A Leading Cause of Damage to Electronics Equipment
Deepak Divan, Georgia Tech School of Electrical Engineering
Electronics equipment normally includes a transient voltage surge suppressor (TVSS) to guard against voltage surges and a ‘power-on inrush current limiter’ (ICL) to limit the current surge that flows when the equipment is powered on. The ICL circuit is bypassed after power-up, and cannot protect against current surges that occur after power-up.
Lightning strikes high-voltage power lines fairly frequently, but only causes a high voltage surge within ~200 meters of the impacted site, affecting few end-users. TVSS devices protect against such rare but damaging voltage surges. On the other hand, every lightning strike on a power line or other power system fault causes a short-duration voltage sag, lasting typically less than 6 cycles, impacting customers up to 200 miles away. As a result voltage sags occur much more frequently than voltage surges. At the end of the voltage sag, the ac line voltage abruptly returns to normal, causing a large current surge because the ICL is disabled. This current surge degrades equipment reliability and life, has the potential to cause as much damage as a lightning strike, and is the leading cause of equipment damage in the field.
This paper will provide the data validating the occurrence of frequent and debilitating current surges, and will discuss a new dual-mode surge protection device that can protect equipment against both voltage and current surges.
Mitigation of Utility Transients and Disturbances Using a UPS or Power Conditioner with an IGBT Rectifier
Hans-Erik Pfitzer, Eaton
The majority of utility outages that occur are not typically a complete loss of voltage, rather they are brown-outs or voltage sags of short duration. Using modern test equipment the ability to produce these severe conditions in high power applications is possible. Given the frequency of these events and the ability to reproduce these conditions in a controlled environment the next logical performance requirements of the modern rectifier become obvious. This paper describes the technology used in a UPS/Power Conditioner that enables ride through operation without a battery. It will discuss the tests performed to validate this claim and the advantages of not requiring a battery during these events.
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Tuesday, October 14, 2008
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