The 230 V CBEMA curve — Preliminary studies

The ITI, formerly CBEMA, curve was developed by the Information Technology Industry Council of the United States of America. The curve describes an AC input voltage envelope which typically can be tolerated by most Information Technology (IT) Equipment. Although the curve ostensibly applies only to IT equipment it is often used throughout the electricity supply industry to provide an indication of the input voltage tolerance of a wide range of equipment. In spite of the fact that the curve was designed to apply to equipment supplied at 120 V 60 Hz nominal voltages it is widely used in Australia which has a 230 V 50 Hz system. This paper details a preliminary study aimed at developing a CBEMA style curve to suit Australian conditions. A range of domestic equipment has been tested to determine sag susceptibility. The types of equipment tested are not limited to IT equipment and represent a cross section of appliances likely to be found in most homes. Overall, results for domestic appliances show that equipment connected to the Australian 230 V network has sag immunity considerably greater than that defined by the ITI Curve. As such, the applicability of the curve for individual pieces of equipment connected to Australian 230 V electricity networks is highly questionable and the need for further work in this area is apparent.