EMC evaluation and analysis of UPS

Computing devices are finding increasing importance day by day. Erratic power supplies pose a serious threat to the reliability and durability of data. The person working on system needs protection of data and UPS thus becomes a necessity. UPS stores energy into batteries and converts back the stored DC into an AC supply. Switching techniques are used to convert DC into AC. Switching of current generates electromagnetic emission which effects the nearby products. The emission generated from UPS may be of conducted type/radiated type or both. Advanced technologies of UPS are also sensitive and hence call for high immunity from electromagnetic noises. Since the computer supply is taken from UPS, hence the UPS shall be immune to power noises/disturbances and shall not generate such noises as well. EMI/EMC evaluation of UPS thus becomes very essential to ensure that the system works satisfactorily in the intended environment. The paper discusses various available specification for EMC evaluation of UPS and analyzes the working environment of UPS. It also highlights probable EMI sources and suppression and immunity improvement techniques for compliance of UPS to national and international norms.