INTERPRETING THE READINGS: Understanding the. CBEMA Curve. ” Determining Susceptibility”. Throughout the sphere of Power Quality you’ll hear the terms. The ITI, formerly CBEMA, curve was developed by the Information Technology Industry Council of the. United States of America. The curve describes an AC. Abstract: The ITI, formerly CBEMA, curve was developed by the Information Technology Industry Council of the United States of America. The curve describes an.

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Due to the importance of the previous CBEMA curve, a working group and several sponsors undertook the task of revising the curve based on actual test results.

The frequency of transient may range from Hz to 5KHz. While there is no harm in using this as a reference to establish a baseline power quality, it is important to recognize that the original intent of the curve was for V single phase computer equipment.

Voltage Disturbance

If ITE is subjected to such conditions, damage may result. Page navigation Document information Table of contents Similar titles.

In other words, t he concept is that if the supply voltage stays within the acceptable power area then the sensitive equipment will operate well. This transient could occur during a temporary fault in the power system followed by clearing of the fault. H, HJ Elsevier A lightning strike, even when reasonably nearby, will often not damage equipment. British Library Conference Proceedings Tables of content are generated automatically and are based on records of articles contained that are available in the TIB-Portal index.


You state “the CBEMA curve shows that voltage levels of even zero can be tolerated for a very brief period of time – 4. The normal functional state of the ITE is not typically expected during these conditions, but no damage to the ITE should result.

File:CBEMA Curve.png

Advanced Search Watchlist Search history Search help. Power Quality in Electrical Systems. They are very much ‘grey areas’ where one needs to consider the effect of the disturbance and define it accordingly.

In the center of the plot is the so called acceptable area. The importance of these especially the second are used to determine the extent of possible current export and inrush during the disturbance. I have been working in an electric distribution utility for more than a decade.

File:CBEMA – Wikimedia Commons

This range is those deviations with extremely sharp rise and fall times deviate from and then return to the normal waveform extremely quickly. The higher the frequency, the higher the attenuation.

These two filters, between them, will establish the devices susceptibility to variations in the mains waveform – and the susceptibility is dependent on distortion vs. Voltage sags, dropouts, and steady state voltages in this region are not expected to damage the ITE equipment. However, cjrve such an event persist for a longer time, then the sensitive equipment might fail.

Note that these are long term changes i. Power Systems Engineering Research Center. The longer the deviation, the more it can affect the capacitor. Press and information Press releases Press Archives. Newer Post Older Post Home. Electrical schemas Diagrams about science Diagrams in English. The best scientific cutve of the curve can be given in terms of a voltage standard applied to the DC bus voltage of a rectifier load.


The magnitude of the transient is expressed as a percentage of the peak 60 Hz nominal voltage not the RMS value. One of the most effective ways to prepare for optimum operation of sensitive electronic equipment is to understand and use the Computer Business Equipment Manufacturers Association CBEMA curve and related guidelines.

The graph below shows the cbena state cuvre variation over a period.

Ahead of the rectifiers and storage capacitor is the EMC filter whose primary purpose is to stop the muck generated by the switching circuit from being radiated onto the mains, and not as protection for the power supply. Power Acceptability CurvesStandards.

SEMI F47 cueve that semiconductor manufacturers may use this standard in their specification whenever they purchase equipment.

It would, however, be erroneous to use them in defining areas of responsibility either for the power supplier or device using the power.

Many will try to use one point to indicate a complicated disturbance. Some of which are unequal ground potentials, Electromagnetic Noise Interference etc. SEMI F47 does not address product quality and the purpose of the standard is to keep the equipment running without any operator intervention when exposed to voltage sags above the tolerance curve.