Conducted Immunity Systems for IEC 61000-4-6 Compliance

BCI testing is an alternative method of conducted immunity testing, where an RF current is injected directly into the cable under test using a current injection probe (typically a BCI clamp). Unlike CDN-based testing, which uses defined impedance coupling, BCI allows for greater flexibility in testing non-standard cable configurations and is often used in automotive, aerospace and military EMC standards.

The clamp is placed around the cable and injects RF signals without direct electrical contact, making it suitable for systems where a CDN is not applicable. It is commonly used for frequencies from 1 MHz to 400 MHz and allows for current level calibration using monitoring probes.

An EM clamp is a non-invasive coupling device used for conducted RF immunity testing, especially in scenarios where CDNs cannot be easily applied. It works by clamping around a cable to inject RF energy using both capacitive and inductive coupling mechanisms. EM clamps are useful for testing cables connected to equipment without standard interfaces, and they are recognised in IEC 61000-4-6 as a valid alternative to CDNs.

They are particularly useful for testing cables connected to peripheral devices like printers, displays or other I/O equipment, where typical injection methods are impractical.

Mains dips and brown-outs refer to short-duration voltage reductions in the mains power supply. These are typically caused by high-load equipment switching on or grid faults. Dips can lead to malfunction or resets in poorly protected devices.

Testing for dips involves simulating sudden drops to specified voltage levels (for example, 70% or 40% of nominal voltage) for defined durations, to assess a product’s ability to ride through without failure. This is part of IEC 61000-4-11 compliance testing.

Mains transients are rapid, high-frequency voltage changes superimposed on the mains waveform. They may be caused by switching events, nearby lightning strikes or power conditioning systems.

Transient immunity testing checks whether equipment can tolerate these disturbances without suffering operational issues or damage. The most common standard for this is IEC 61000-4-4, often referred to as Electrical Fast Transient (EFT) or burst testing.

Mains surge testing evaluates a device’s ability to survive and function correctly during high-energy overvoltages, such as those caused by lightning strikes or power grid switching.

Testing simulates these surges using defined voltage and current waveforms (typically 1.2/50 μs voltage and 8/20 μs current pulses), and is specified under IEC 61000-4-5. Devices must either absorb or reject the surge energy without breakdown or loss of performance.

ESD testing replicates the discharge of static electricity from a human body or object into a device. This is one of the most common sources of real-world failure in electronic systems.

The test simulates contact and air discharges using specialised ESD simulators, applying kilovolt-level shocks to buttons, ports, seams and enclosures. ESD testing is governed by IEC 61000-4-2 and helps ensure devices will not reset, lock up or become damaged when touched.