Protection of modern supersensitive electronics used in power systems (Digital Protective Relays (DPR), control devices and microprocessor-based communication equipment) against High Altitude Electromagnetic Pulse (HEMP) and other Intentional Electromagnetic Interferences (IEMI) is a vital task for today's world [1, 2]. Measures and methods of protection against HEMP and IEMI are well defined and described in technical literature [1, 2]. However, they usually require fundamental change difficult to realize in existing power systems. The article discusses the range of measures and simple technical means designed for existing power systems.