Читать книгу Maintaining Mission Critical Systems in a 24/7 Environment - Peter M. Curtis - Страница 36

A facility that is being built from the ground up can use proper design and installation of components that can aid in the protection from EMP. Architectural shields, as well as the use of stand‐alone shielded enclosures, are a great starting point. Through the use of architectural shielding, construction techniques can turn hallway in waveguides that can be used to meaningfully attenuate EMP or any other high RF field. Beyond shielding on the facility level, both powerline RF filtering and lightning protection can also be utilized as a “frontline” of defense. Unless the facility was “super RF secure” and most likely underground, the chances of the effects of EMP entering a facility is high.

In most cases, the equipment that would need to be protected would be classified as either commercial or industrial‐grade equipment. The selection and use of equipment that is European Union CE marked is the best choice for these cases. The mandatory CE marking ensures that products sold within the European Economic Area, and outside, meet the standards for health, safety and environmental protection. The reason for this is, as opposed to a piece of equipment that is FCC approved, CE Marked units meet not only EMI emissions requirements but also immunity or susceptibility requirements. By meeting these requirements, the equipment in question is attesting to the fact that it can withstand harmful RF energy either being conducted or injected into its power and signal leads. It can also withstand RF energy being radiated at it. Therefore, using such equipment provides another line of EMP defense.

An even greater line of defense can be achieved if “military‐grade” equipment is selected that has been testing in accordance with MIL‐STD‐461G, test methods RS105 and CS116. Test Method RS105, “Radiated Susceptibility, Transient Field,” tests the equipment’s ability to withstand the “radiated effects” of an EMP event. The test field level used for the test is 50,000 volts per meter (V/M) and is applied through a transmission line type antenna couple to a transient generator.

Test Method CS116, “Conducted Susceptibility, Damped Sinusoidal Transient, Cable and Power Leads, 10KHz to 100MHz”, tests the equipment’s ability to withstand the result of EMP energy being “conducted into” the equipment through its power leads and interconnecting cables. When performed, the damped sinusoidal transient waveforms are inductively coupled onto the unit’s power and interconnecting cabling. The minimum set of test frequencies are typically 10KHz, 100KHz, 1MHz, 10MHz, 30MHz, and 100MHz.

An approach that is radical and less frequently used is to secure backup equipment (such as communications). This approach can be expensive and sometimes impractical; however, if key pieces of the equipment can be clearly identified, storing backups in a secure storage facility is a viable option to protect from EMP. The storage facility should be a mil grade RF shielded enclosure, ideally below ground level, and should have no power supplied to it. It should be self‐contained with any needed lighting, battery power. This is simply an RF secure storage room, not an operations center. Some types of equipment that are stored are satellite phones and professional‐grade “walkie‐ talkies” so that you can re‐establish some forms of communications within your building or on your property after an EMP event. Such facilities can also be used to store hard drives that can contain backup data.