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CISPR 11: “Industrial, scientific and medical equipment – Radio-frequency disturbance characteristics – Limits and methods of measurement”
This is an important standard limiting radiated and conducted emissions from non-consumer electronics, which have different concerns in terms of operating environments than tests such as FCC/ANI C63.4.
Like most CISPR standards, CISPR 11 aims to control the unintentional emission of RF energy from equipment, in this case industrial, scientific and medical (ISM) equipment. These are units designed to operate in more restricted areas than general consumer electronics. They divide ISM equipment into two classes, Class A and Class B, where Class B equipment may be used in a residential setting. However its main concern is higher power equipment, such as arc welders, that are not found in casual use. It also distinguishes between Groups 1 and 2, where Group 2 equipment includes intentional generation of RF signals. A newly revised version of CISPR 11 was published in 2024 and can be purchased here. It informs IEC 60601-1-2 on medical equipment.
CISPR 11 looks at both conducted and radiated emissions, although as Henry Ott pointed out years ago, in these cases conducted emissions tests are really radiated emissions controls in disguise. Section 6 lays out the emissions limits for different equipment in different situations, and Sections 7 and 8 concern measurements methods. Limits start at 150 kHz and, depending on application, go up to 18 GHz. They are generally expressed as both Average and Quasi Peak levels. It refers back to CISPR 16 for most measurement equipment specifications.
The test methods of CISPR 11 acknowledge that the equipment that falls under this standard may be considerably more complex than the kinds of modules you might test under MIL-STD-461 or CISPR 25. Hence it allows Class A equipment to be tested in situ (on site) if needed. As such, it has a different approach to, for instance, characterizing ambient noise levels. It also describes different kinds of LISN/Artificial Network configurations. It spends quite a bit of time concerning cable arrangements, which can be critical for accurate, repeatable measurements.
Some useful information in the appendices (Always Read the Appendices!) includes protection and concerns when using spectrum analyzers around ISM and other potentially higher power equipment; ways to handle existing RF transmissions in the environment when you can’t use a shield room; and worldwide frequency allocations and particular safety-related bands that should be protected.
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Some limits changed in the 2024 revision, mostly to cover newer equipment configurations. It also now addresses industrial robots specifically.
ICNIRP: “ICNIRP GUIDELINES FOR LIMITING EXPOSURE TO ELECTROMAGNETIC FIELDS (100 KHZ TO 300 GHZ)”
ICNIRP 2020 Guidelines help determine limits on electromagnetic fields for human protection.
ICNIRP (often pronounced “ick-nerp”) is the International Commission on Non-Ionizing Radiation Protection. They are a global research group that has been studying the safety implications of electromagnetic radiation (as opposed to nuclear ionizing radiation, e.g. Chernobyl), from DC to 300 GHz, since 1992. (The commission was chartered in 1992, but includes research and researchers going back to 1973.) They publish a wide variety of freely available guidelines, statements, and papers on their website. The most recent major guideline document for RF energy (100 kHz - 300 GHz) was published in 2020 and can be downloaded here.
ICNIRP has published major guidelines on safe levels of electromagnetic energy for both the general public and specialist workers in 1998 and 2020. It has had a significant influence on related standards such as ANSI C95.1. The two main categories of potential EM field/human body interactions with RF fields are nerve stimulation (more prevalent at lower frequencies) and tissue heating. Probably the table that product designers will reference the most is Table 2 on basic restrictions (2020), as seen below.
SAR = specific absorption rate, which is the key metric when looking at exposure from devices such as cell phones.
After this table there is a lot more information on refining these levels for different scenarios. And as always, there is extremely useful information contained in the appendices.
There is a 2010 document that covers 1 Hz - 100 kHz for low-frequency effects and exposure to magnetic fields. There’s also a 2014 document with guidance on fields that vary at less than 1 Hz.
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In general, the exposure guidelines have relaxed over time, as additional research allows the commission to refine its knowledge of human effects and move away from worst-case assumptions. However, since many medical devices are still in circulation that were built assuming the stricter guidelines from 1998, if you need to set default limits, you should use the 1998 document as your guidance.
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ICNIRP has gotten drawn into numerous controversies and public panic about high voltage power lines, cell phones, 5G specifically, and other topics. If you have concerns about any of these topics, I highly recommend you go through their meticulously researched and documented (and freely available) publications on your specific concerns. I have learned a lot about EM interactions with human bodies through reading their research.