By Jim Kidd
PHILADELPHIA—Electromagnetic interference (EMI), virtually everyone has heard of it, and many have experienced its effects, both at home and in the Fleet. All electronic and electrical equipment create electromagnetic fields and emissions, and many can be affected by the fields and emissions produced by nearby equipment, otherwise known as susceptibility.
The electromagnetic environment aboard ship has always been harsh. Higher-powered equipment, operating at both power frequencies, as well as radio and microwave frequencies in close quarters and proximity to each other, all confined within a highly reflective environment, have created operating difficulties for shipboard equipment for decades.
The hull, mechanical and electrical (HM&E) areas have historically been less severely affected than combat systems. While electrical systems can be the source or victim of EMI, it is generally higher frequency elements that are the focus of most issues. The electromechanical nature of many HM&E-related systems from the 1950s through 1980s had left the electromagnetic compatibility (EMC) concerns of these systems as an afterthought. As electronic elements began to replace the mechanical ones in the 1990s, EMI grew as a problem below decks as well as above. Machinery spaces were no longer largely immune.
Throughout the late 1990s and into the 21st century, the proliferation of electronics in HM&E systems has been extensive. PLCs replaced relays; microprocessors replaced switches. “Dumb” equipment has become “Smart.” Wireless technology is pushing the envelope. Electromagnetic interference has left ships dead in the water.
The electromagnetic environment aboard ship has become much more difficult and will continue to degrade as more and higher power electronic elements are introduced shipboard, at a time when reduced manning is relying on “Smart” systems to function without flaw.
The EMC Laboratory has been providing electromagnetic interference support to the Fleet for more than a decade. Established in 1991, the EMC Lab, located in Bldg. 1000, has been providing testing in support of military research and development for Navy, Marine and Army systems. Its main function has been in providing electromagnetic testing in support of new technology acquisition (primarily to MIL-STD-461), as well as technical support in resolving EMI-related problems in the Fleet.
The EMC Laboratory, part of Code 9533, led by Section Head Joe McGillian, plays a leading role in the Navy’s EMC community. As part of the Technical Authority Pyramid, the technical warrant holder for Shipboard Electromagnetic Compatibility, Ron Bradley (NAVSEA 62E), has designated NAVSEA Philadelphia Code 953, led by Vince Difillipo, as the engineering agent (EA) for HM&E systems electromagnetic compatibility. The EMC Lab provides the technical expertise to perform this role. This authority extends to guidance and review in acquisition specifications with respect to EMI/EMC requirements; review and approval of EMI test procedures and reports; and resolution of identified EMC issues in HM&E systems.
Additionally, the technical capabilities of the EMC lab provide T&E services to the Navy in various ways. Compliance to testing to the military’s EMC requirements (MIL-STD-461) is a primary function. The EMC-related evaluation and militarization of COTS equipment is another service provided as part of the lab’s functions in helping to develop an EMC compliant, yet cost effective, Fleet. Assisting various LCMs and ISEAs in developing new systems and understanding the role and effect that EMC plays in the acquisition and life cycle of their systems.
The lead EMC engineer for Carderock Division is Jim Kidd, who handles the majority of EMC-related issues in support of the EA designation. Any questions, concerns or need of EMC-related assistance in specification, acquisition, and review may be addressed to him (215-897-7685 or kiddja@nswccd.navy.mil).
Shipboard EMC will remain a growing threat and challenge of which LCMs will have to be aware. The old adage that “an ounce of prevention is worth a pound of cure” was never more true than with respect to EMC. Addressing EMI/EMC issues at the earliest stages of equipment life cycles, most notably in acquisition, is the best way to ensure EMC issues don’t become EMI problems. The EMC Lab stands ready to support such efforts.
Posted by yw at November 8, 2004 06:54 PM