{"id":3817,"date":"2026-07-08T07:34:33","date_gmt":"2026-07-08T07:34:33","guid":{"rendered":"https:\/\/theemcnews.co.uk\/?page_id=3817"},"modified":"2026-07-08T07:35:29","modified_gmt":"2026-07-08T07:35:29","slug":"standards-practice-why-so-many-immunity-susceptibility-tests","status":"publish","type":"page","link":"https:\/\/theemcnews.co.uk\/index.php\/standards-practice-why-so-many-immunity-susceptibility-tests\/","title":{"rendered":"Standards Practice: Why So Many Immunity\/Susceptibility Tests?"},"content":{"rendered":"\t\t
\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t

Hello, and welcome to the first installment of this new column, \u201cStandards Practice.\u201d I\u2019m Karen Burnham, currently Vice President of Standards for the\u00a0IEEE<\/a>\u00a0EMC<\/a>\u00a0Society. I\u2019m hoping to use this space to do two things: educate people about standards and also use standards to educate people about\u00a0electromagnetic compatibility<\/a>\u00a0(EMC<\/a>) engineering.<\/p>

I\u2019d like to start out by discussing the wide variety of\u00a0immunity<\/a>\u00a0standards (known in defense\/aerospace as\u00a0susceptibility<\/a>\u00a0standards) that are out there and why we need so many of them. I will focus on defense\/aerospace and automotive since those are the areas I\u2019m most familiar with. However, there are similar motivations behind medical standards, such as\u00a0IEC<\/a>\u00a060601 and plenty of others. Here, I\u2019ll be referring to MIL-STD-461 Rev G and JLR-EMC-CS from Jaguar Land Rover (JLR), both easily available. The JLR standard is broadly representative of those automotive OEMs (original equipment manufacturers, such as Ford or Toyota) impose on module suppliers.<\/p>

Probably no one\u2019s favorite is the standard\u00a0Radiated Immunity<\/a>\u00a0test. This is exemplified by RS103 in MIL-STD-461 for defense\/aerospace and JLR RI 114 for automotive. The idea behind this test is for equipment to be immune to its electromagnetic environment. Generally speaking, the main threat to a module will be the\u00a0RF<\/a>\u00a0transmitters co-located on the same platform. Imagine a communication system on an aircraft interfering with an avionics sensor package. That class of threats should be accounted for very explicitly when a program is tailoring its\u00a0radiated immunity<\/a>\u00a0requirements.<\/p>

What\u2019s harder to narrowly characterize is the broader array of\u00a0RF<\/a>\u00a0transmitters in the world. While I don\u2019t expect to have my electronics interrupted by the local\u00a0AM<\/a>\u00a0radio\u00a0transmitter<\/a>, that may change if I drive up to the base of its broadcast tower. Then there are things like aircraft-tracking radar on military platforms like aircraft carriers and in civilian applications at airports. See Figure 1 to compare the levels specified by RS103 and RI 114. The transmitted threats can change significantly over time as different systems are developed, moved, or upgraded. In an example of testing evolving along with consumer technology, the automotive industry adopted\u00a0radiated immunity<\/a>\u00a0testing such as JLR RI 115 that specifically mimics cell phone signals since passengers and drivers can be counted on to put or drop their cell phones in the most inconvenient possible places.
\"Figure<\/p>

(a)<\/p>

\"\"<\/p>

(b)<\/p>

Figure 1: Comparing\u00a0radiated susceptibility<\/a>\/immunity<\/a>\u00a0levels from (a) MIL-STD-461 and (b) JLR RI 114.
<\/em><\/h6>

Leaving aside RS101 and 105 from MIL-STD-461 (susceptibility<\/a>\u00a0to magnetic fields and\u00a0EMP<\/a>, respectively), we can then look at the wide array of conducted\u00a0immunity<\/a>\u00a0tests. IEC-61000-4-2 and derived standards like MIL-STD-461 CS118 and Jaguar Land Rover CI 280 are all meant to address the risk of human\u00a0ESD<\/a>\u00a0to electronics. The JLR standard goes up to \u00b130 kV for certain units, while CS118 only specifies up to \u00b115 kV, presumably because the military has more control over how its equipment is used and can train personnel in a way you can\u2019t with an average driver.<\/p>

Continuing on, bulk current injection tests such as MIL-STD-461 CS114 and JLR RI 112 represent two threats: lower frequency ranges that are difficult to test via radiated methods due to chamber limitations but easily picked up by long cable runs and also\u00a0crosstalk<\/a>\u00a0between conductors in those long runs.<\/p>

All units must be immune to the\u00a0noise<\/a>\u00a0carried on shared power buses, such as voltage ripple from power supplies. In MIL-STD-461, that\u2019s covered by CS101; in the automotive world, you might look at JLR CI 210. See Figure 2 to compare the levels between the two. For a nominally 12 V system, both have max levels of 2 V (126 dB\u03bcV), but the automotive standard assumes the\u00a0noise<\/a>\u00a0will get worse with frequency, whereas the defense standard assumes it will go down with frequency.<\/p>

\"Figure\"FigureFigure 2: Comparing test levels for conducted\u00a0immunity<\/a>\/susceptibility<\/a>\u00a0addressing low-frequency\u00a0noise<\/a>\u00a0from power supplies.<\/em><\/h6>

\u00a0<\/p>

Aside from the\u00a0susceptibility<\/a>\u00a0requirements specifically applied only to\u00a0RF<\/a>\u00a0systems (CS 103\/104\/105) or large naval vessels (CS109), the remaining MIL-STD-461 tests are largely applicable to threats such as various transients or induced currents produced by direct or nearby lightning strikes or related impulses (CS115\/116\/117).<\/p>

The automotive folks have even more on their plate: wire-to-wire coupling when transients are induced by inductive loads switching on and off (JLR RI 130); or when there are continuous disturbances from pulse width modulated, high current modules (JLR RI 150); conducted transients resulting from loads switching on or off, particularly sudden voltage dips or a load dump (JLR CI 220), power cycling in cold start conditions (JLR CI 230);\u00a0ground<\/a>\u00a0voltage offsets due to using chassis as current return (JLR CI 250); and\u00a0immunity<\/a>\u00a0to\u00a0transient<\/a>\u00a0voltage dropouts that can occur for any number of reasons, including the loosening of pins over time and potentially losing connection when going over potholes, for instance (JLR CI 265).<\/p>

All of which is to say, there are a lot of different ways to disrupt a system using either radiated or conducted electromagnetic energy. Different industries have specific threats that they want to address with their\u00a0EMC<\/a>\u00a0testing requirements based on their operating conditions and platform architecture. Keep in mind that each test represents some real-world condition, even if it\u2019s a few steps removed or abstracted. When flowing requirements to your own\u00a0EUT<\/a>, give some thought to making sure that each scenario is genuinely applicable and consider making tailoring adjustments to your requirements if they don\u2019t make sense.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

Hello, and welcome to the first installment of this new column, \u201cStandards Practice.\u201d I\u2019m Karen Burnham, currently Vice President of Standards for the\u00a0IEEE\u00a0EMC\u00a0Society. I\u2019m hoping to use this space to do two things: educate people about standards and also use standards to educate people about\u00a0electromagnetic compatibility\u00a0(EMC) engineering. I\u2019d like to… <\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"elementor_header_footer","meta":{"footnotes":""},"class_list":["post-3817","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/3817","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=3817"}],"version-history":[{"count":4,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/3817\/revisions"}],"predecessor-version":[{"id":3821,"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/3817\/revisions\/3821"}],"wp:attachment":[{"href":"https:\/\/theemcnews.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=3817"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}