Intentional EMI

Intentional EMI (IEMI) is an emerging phenomenon which has been causing facility operators and infrastructure stakeholders to re-think their approaches to network and site installation design. Essentially, IEMI consists of the deliberate coupling of electromagnetic energy into a system or facility in order to impair, damage or manipulate the facility or system in some way. Similar in intent to a cyber attack, an IEMI event may be intended to simply compromise the facility owner or operator, but attempts have been made to use IEMI to access and steal data from a victim system, or even to manipulate or corrupt system data in a precise and deliberate manner (IEMI Threats for Information Security: Remote Command Injection on Modern Smartphones). In 2020, Belgian researchers at were able to demonstrate that they could re-construct the images on a hidden video monitor simply by directing an antenna towards the HDMI cable connecting the monitor to its computer and analyzing the ‘captured’ EM emissions (EMC Magazine 2nd quarter 2021).

The danger of IEMI is that it can access a system from outside that system as long as it has some physical means for its interference signals to propagate to its target. This means could be cabling or metallic structures of any kind, or just an unshielded path over the airwaves. A broadband signal would likely be used if the attackers have limited knowledge about the target, but a specific narrow band pulse would be more effective if the nature of their target and its intended coupling path were well understood by them. In either case, the best defence against IEMI is basically the same as it would be for EMI: characterize the electromagnetic properties of the networks and installations, and its potential vulnerabilities, and then implement an effective strategy of shielding, filtering, grounding and component isolation. In some jurisdictions, regulatory or recommended standards have been coming into effect to ensure that new and existing facilities are protected against IEMI. (Protecting Industry from HEMP and IEMI)

Smart Grid

The Smart Grid is a system of intelligent devices distributed across electrical power networks, combined with communications networks which connect the devices to each other and to the utilities’ central monitoring and control stations. These intelligent networks monitor and control every functional aspect of the transmission and distribution systems themselves, including fault management, power quality and switching functions. Smart meters installed at customer points of connection automatically monitor energy usage in real time, both for billing as well as energy management purposes. Demand side management devices installed within customer premises also allow the Smart Grid to automatically manage customer loads at critical periods to avoid blackouts, brownouts or other undesirable conditions. In an environment of Distributed Electrical Resources (DERs), the Smart Grid facilitates a seamless management of a diversity of electrical generation or storage resources that can be switched or routed over the network for optimal results.

The Smart Grid is generally viewed as the network model of the future, and the basis of the emerging green electrification infrastructure. The communications networks interconnecting all of the Smart Grid elements can be implemented in a variety of ways. One approach has been to use the power lines themselves as a transmission path, allowing utilities to operate their Smart Grids over a completely dedicated communications system, independently of any public networks. This approach is known as Power Line Communications (PLC).

In spite of the advantages offered by PLC networks, many of the utilities employing this solution have been experiencing issues with their Smart Grid communications due to high frequency interference on their power lines. The sources of this interference are the complex electronic systems at utility stations, the power electronics and other digital devices on the DERs, and even the distributed accumulation of Smart Grid devices themselves, as well as various switching and other transients on the networks. (Analysis of noise in broadband Powerline Communications (B-PLC) in frequency range of 150kHz–30MHz | IEEE Conference Publication | IEEE Xplore) There are many advantages to large networks of interconnected grids, but this also creates a large propagation medium for interference sources all over the networks. Similar issues exist for utilities which simply route their Smart Grid communications over public networks, since those facilities can also become part of the EMI propagation path. Individual devices can also simply be impaired by local EMI conditions in proximity to power electronics or other nearby sources, or by interference that has been delivered over the grid from other points on the network. Research groups have demonstrated that Smart meters can be, and have been, adversely affected by ambient EMI effects, causing meters to report high usage levels when there has been little or no energy consumption, or reporting little or no consumption when usage has in fact been high. (Misreadings of Static Energy Meters due to Conducted EMI caused by Fast Changing Current | IEEE Conference Publication | IEEE Xplore)

These issues can be avoided, remediated or mitigated by developing adequate electromagnetic characterizations of the overall networks and their subsystems, and by implementing appropriate design, layout, filtering, shielding and grounding strategies throughout the network. The Smart Electric Power Alliance (SEPA) is an association of utilities, engineering groups and other stakeholders. Their recommendation is that before any Smart device is deployed in any network environment, that environment needs to be electromagnetically characterized to see whether the device’s EMI specifications are adequate. When that is not the case, additional EMI mitigation strategies would need to be put in place to sufficiently enhance the device’s immunity in those environments. (Electromagnetic Compatibility (EMC) Assessment, Testing and Mitigation | SEPA ( reaffirms the fact that even though a device receives a satisfactory EMI rating in isolation during certification testing, it may still behave in unexpected and unsatisfactory manners when placed within certain systems or environments.

EMI Basics

EMI is caused by unwanted, or interfering, currents and radio waves that find their way into an electronic system or device. Its effects can be disruptive, or even destructive.  And any piece of electronic equipment, from computers and small motors to radios and cellphones, can emit EMI. EMI can also be due to natural sources such as lightning.

EMI can affect our communications and power infrastructures, undermining our services and even causing failures. But many people are not aware of these effects and their connection to the day-to-day issues they may themselves be experiencing with technology. There’s a tendency instead to just accept the issues as ‘just how it is’. In many cases, systems that we depend on may be malfunctioning due to interference without us even realizing it. 

The effects of the high frequency pulsed signalling which is now typical of modern communications and control technologies can be difficult to track, measure or predict (Electromagnetic Interference Testing (EMI) Basics – Part 1 | EMC Live). Random coupling into nearby circuitries can result in corrupted data and control errors; when the errors are minor, they may remain undetected until their cumulative effects result in more obvious, and apparently inexplicable problems. Similar issues may exist in any environment in which chaotic or intermittent interference sources are present.

Our reliance on technology will continue to increase, and so there will be more and more electronic systems in closer proximity to one another, and operating at higher frequencies than ever. Everything is becoming interconnected either deliberately or unintentionally, so the effects of EMI on our technologies are being amplified more than ever before. 

The ability of digital RF devices to share a common environment without any impairments to their functionalities or inter-operability is often referred to as wireless co-existence (FDA requests attention for wireless coexistence and RF interference risks | Philips Engineering Solutions). In these cases, the effects of mutual EMI on devices need to be considered both at the physical and protocol layers. It’s not difficult to imagine why this would be a critical factor in environments such as hospitals, where high concentrations of wireless monitoring devices are present. 

A recent example of wireless co-existence issues is the USA’s FAA decision to effectively delay 5G deployments near certain US airports (5G and Aviation Safety | Federal Aviation Administration ( The carriers were planning to implement 5G services over the lower C-Band (3.7-3.98 Ghz) portion of the spectrum, which is to close to the upper C-Band (4.0-4.4 Ghz) used by the radar altimeters of large aircraft (5G and Aircraft Safety: How Simulation Can Help to Ensure Passenger Safety ( Obviously, it would be important to have confidence that a large aircraft landing in poor visibility would not become unable to read its own altitude just because someone made a cell call.

Renewable Energy Systems

A key factor in the feasibility and efficiency of modern grid-connected renewable energy systems is the increasingly sophisticated power electronics technology which controls and manages the generation, transfer, and distribution of electrical energy throughout the interconnected systems.  Inverters, coreless transformers, DC-DC converters and other power converters, are all examples of the power electronics devices which lie at the heart of all modern electrification technologies, whether they are grid-connected PV arrays, stand-alone wind turbine systems, or electric vehicles and charging stations. Their versatility and power-handling capabilities, along with their networking and reconfigurability features, have made it possible to plan and build the electrification infrastructures that are seen emerging today. 

While the outputs of power electronics circuits have become increasingly clean and efficient, there has also been a significant increase in the high frequency electromagnetic by-products of these systems, in the form of electromagnetic interference (EMI) which can leak out of the of a power electronics device through various mechanisms. Given the opportunity, these parasitic energies can propagate over nearby structures, cabling and other system components. The nature and extent of this propagation is often unpredictable. 

In other words, power electronic devices which may operate within acceptable EMI limits when tested in isolation (i.e. in product certification testing), can display different and unexpected behaviors and effects when placed within a system. The types, lengths and orientations of cable runs, the structural configurations and locations of metallic frameworks, and the grounding strategies being utilized are just some of the situational characteristics which may affect the propagation and intensity of interference signals on a system.

These unwanted and harmful effects can be mitigated or removed with appropriate shielding, filtering, grounding and other strategies. They can also be largely prevented at the design and installation stages by considering favorable options for system layouts and locations. In order to successfully implement those strategies, however, proper electromagnetic surveys and analyses first need to be undertaken, and should be followed up with adequate monitoring to validate their results.

These effects primarily occur due to the high switching frequencies, short pulse rise times, and high circuit densities which must be designed into the systems to produce the versatile and efficient outputs that are being demanded of them. Modern power electronics designs have been moving towards the use of Wide Band Gap (WBG) semiconductors such as GaN and SiC. These devices are capable of operating at higher frequencies and at higher power levels, potentially leading to energy systems with higher power capacity and higher efficiency.  However, due to their high frequency characteristics, they can also produce increased EMI. Many of the design challenges related to WBG converter development has to do with finding a balance between those effects. (Analysis and Suppression of Conducted Common-Mode EMI in WBG-based Current-Source Converter Systems | IEEE Journals & Magazine | IEEE Xplore)

These converter-based issues have become an area of research interest for organizations such as IEEE’s Electromagnetic Compatibility Society (EMCS) and Power Electronics Society (PELS). 

Ground Reflections Electromagnetic Systems and Engineering Inc.

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