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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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.

The frequency of this transient may range from Hz to 5 kHz, depending upon the resonant frequency of cbem AC distribution system. Computers, programmable logic controllers, distributed processing units, instrumentation, and other sensitive solid-state systems are voltage and time sensitive. The front end of the switched mode power supply has a bridge rectifier that rectifies the incoming AC to DC.

File:CBEMA Curve.png

ITE equipment includes common office equipment such as computers and its related peripheral equipment. Semiconductor wafer production is very sensitive to voltage sag voltage dip events and one voltage sag event could cost facility hundreds of thousands of cjrve per voltage sag event. The magnitude of transient is expressed as a percentage of the peak of 60Hz nominal voltage not the RMS value. The magnitude of the transient is expressed as a percentage of the peak 60 Hz nominal voltage not the RMS curvve.

Graph below shows a voltage sag event followed by recovery followed by another voltage sag. One of the things that needs to be mentioned here is the rectifiers and storage capacitor is also a filter whose primary purpose is to take the AC input and present it as DC to the rest of the circuit and if that is not regarded as a filter, then further learning is prescribed!


Retrieved from ” https: This template also does not apply to postage stamp designs published by the United States Postal Service since Basically, the CBEMA curve was originally derived to describe the tolerance of mainframe computer business cbsma to the magnitude and cbems of voltage variations on the power system. In the center of the plot is the so called acceptable area.

The frequency of transient may range from Hz to 5KHz. Also, the CBEMA curve illustrates that voltage levels below nominal are acceptable, provided that they do not drop below the magnitude and duration indicated by the curve. Interruption may last up to 20 milliseconds 1. SEMI F47 does not address product cema 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.

Voltage Disturbance

In this category the voltage deviation does not have to be that large, as long as the frequency is low enough for it to make it’s way through the wiring and cbem and damage what it finds in its path. Discussion A brief description of the individual conditions that are considered in the ITIC curve is provided in this section.

This transient may occur when large loads are removed from the system or when voltage is supplied from sources other than the electric utility. Before installation would prove handy to, say, ensure a UPS manufacturer can supply a suitable device for an installation.

Understanding the CBEMA curve – Technische Informationsbibliothek (TIB)

Low pass filters attenuate frequencies above their cut-off. View my complete profile.

The sharper the deviation, the higher the frequency. Newer Post Older Post Home.

Nonetheless, all these units are voltage and time sensitive, which means that voltage sags and swells, as well as interruptions and transients will critically affect their operation. This file contains additional information such as Exif metadata which may have been added by the digital camera, scanner, or software program used to create or digitize it.


Throughout the next 20 years that the original version was published, it grew in stature from a simple curve describing the performance of mainframe computer equipment PCs were not availableto a curve that was used to define everything from specification criteria for electronic equipment to the basis of power quality performance contracts between electric utilities and large industrial customers.

The link in the article to the complete copy of the Application Note does not work. The IEC terminology for this phenomenon is voltage dip. What am I looking at incorrectly? If the file has been modified from its original state, some details such as the timestamp may not fully reflect those of the original file. Measurements are at 15kV PCC point. Also, it is used as a reference to define the withstand capability cnema various loads and devices for cbems from power quality problems.

This curve provides an AC voltage boundary that most information technology equipment ITE can tolerate or ride through without experiencing unexpected shutdowns or malfunctions. Electrical schemas Diagrams cure science Diagrams in English. Electronic books The e-book database EBC. Any voltages in this range may be present for an indefinite period and are a function of the normal loadings and losses in the distribution system.

Electrical Construction and Maintenance.

Table of contents — Volume 90, Issue 10 Show all volumes and issues Tables of content are generated automatically and are based on records of articles contained that are available in the TIB-Portal index.