Conducted immunity refers to the device’s ability to resist unwanted RF voltages and currents that get coupled to the external wires and cables. These coupled RF voltages and currents are nothing but unwanted noise that could hamper the intended functions of the device.

What is Conducted Immunity Testing?

Conducted immunity testing is used to determine whether the Equipment Under Test (EUT) has the ability to comply with the given limits to function in an RF-exposed environment. This testing is done by simulating potential disturbances from other devices powered by the same power network or inductively coupled onto its external wires or cables. 

What is the Standard for Conducted Immunity Testing?

The IEC 61000-4-6 by the International Electrotechnical Commission is the RMC standard for induced disturbances caused by electromagnetic fields coming from intentional radio frequency (RF) transmitters in the frequency range of 150 kHz to 80 MHz.

The test levels of the unmodulated disturbing signal (Vrms) are shown in the table below:

The “X” level is for the special cases, which can be above, below, or between any levels. It has to be specified in the equipment specification.

What is the Test Equipment Required for Conducted Immunity Testing?

Major Test Equipment required for the conducted immunity testing is:

• Signal Generator
• Power Amplifier and Power Meter
• Coupling Devices:
• CDN (Coupling-Decoupling Network)
• EM Clamp
• Current Injection Clamp
• •Direct Injection
• Analyzers, oscilloscopes for detection

What is the Test Method for Conducted Immunity Testing?

The test usually is run by a software-controlled test system. An RF signal generator and the EUT are connected to the mains AC supply. The RF signal generator and amplifier generate an electromagnetic field. This electromagnetic field is injected into cables such as cables, data cables, or power cables of the EUT by an injection device. The EUT is also connected to an analyzer or oscilloscope to monitor the current and voltage waveforms and operation of the EUT. The most common injection devices are CDN, BCI probs, EM Clamp, and direct voltage injection equipment. A similar process is carried out for voltage injections.

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