IEC 61000-4-36:2020 pdf download – Electromagnetic compatibility (EMC) – Part 4-36: Testing and measurement techniques – IEMI immunity test methods for equipment and systems.
5.2.4 Published conducted IEMI environments Unlike the situation with radiated IEMI sources, examples of conducted IEMI sources are less common. However, it has been shown that many conducted EMC tests exist within published civilian EMC documents such as IEC 61000-4-18 [5], IEC 61000-4-4 [6] and IEC 61000-4-25 [2] and that the sources that generate these test waveforms can be uprated or applied to equipment ports in a different way or otherwise used for malicious effect. There are also various military standards that contain relevant conducted tests. 5.3 Interaction with victim equipment, systems and installations General 5.3.1 The magnitude of the IEMI environment impinging on a victim system is primarily dependent upon two factors: 1) the range or distance between the IEMI source and the victim electronics; 2) the propagation loss, including the attenuation properties of intervening barriers. It is important to note that radiated IEMI interacts not only with apertures and structures, but also cables. The total EM disturbance presented to the victim electronics inside is therefore a function of the direct radiated IEMI and the coupling of this IEMI to EM conductors such as cables, pipe-work and ducting. When determining an appropriate test level for a particular radiated IEMI environment of concern, an assessment of the transfer of the IEMI to the victim electronics inside the building is required and this should include any attenuation afforded by the building material, propagation loss and any other aspects that can affect the resulting currents or voltages presented to the equipment. Figure 1 shows a typical radiated and conducted IEMI scenario with a vehicle-mounted IEMI source illuminating a building and separately injecting into a power cable. The fields generated by the radiating source penetrate through apertures and separately couple to conductors (both outside and inside the building), generating induced currents and voltages that can affect the victim electronic equipment.
It should be noted that cable attenuation and attenuation afforded by lumped components (such as transformers) should be considered when determining the currents and voltages presented at the electronic equipment. It should also be noted that different coupling modes (i.e. common mode or differential mode) can result in very different path losses during the propagation. 5.3.2 Protection level Given the discussion above it can be implied that victim electronics located inside equipment, systems or installations will have an “inherent protection level” which is a function of the physical distance between the IEMI source and the victim electronics and the loss in the propagation channel. A discussion on the radiated and conducted interaction of IEMI sources within buildings is provided in Annex C. Examples of protection levels are indicated in Table 3. These levels have been identified using the information in Annex C. However, it is highly important that the actual protection level is quantified through measurements, possibly as part of a site survey. Test methods which can be used to assess the barrier attenuation/propagation loss are discussed in Clause 6.
6 Test methods 6.1 Derivation of applicable test methods A detailed discussion on test methods is included in IEC TS 61000-5-9 [7]. The test methods summarised below encompass the evaluation of the “example protection level” and the immunity test level for potential victim equipment. As IEMI falls into two main categories, namely radiated and conducted, the methods for testing against IEMI fall broadly into the same categories. Testing against radiated IEMI can be undertaken with the IEMI source of interest, a simulated environment such as that shown in IEC TR 61000-4-35 [8], or by injecting the signal expected to be induced into conductors by exposure to the IEMI radiated environment. The latter relies on knowledge of the transfer function 2 of each conductor of concern (typically these conductors are cable bundles that carry power and/or data that is vital to the continuing function of the equipment or system).