Conducted Susceptibility

A conducted susceptibility test is a procedure used to evaluate how an electronic device or system behaves when subjected to electromagnetic interference (EMI) that is conducted through power or signal lines. This test is crucial in ensuring that devices can operate correctly in environments where they might encounter electromagnetic disturbances, such as industrial machinery, medical facilities, or areas with heavy electronic equipment usage.

IEC 61000-4-6: Specifies the test method for immunity to conducted disturbances induced by radio-frequency fields.

Key Concepts

Conducted Interference:

This refers to unwanted electromagnetic energy that is transferred through electrical conductors, such as power lines or signal cables. Unlike radiated interference, which is transmitted through the air, conducted interference travels along wires and can directly affect the device's circuits.

Frequency Range:

Conducted susceptibility tests typically focus on specific frequency ranges that are known to cause problems in electronic circuits. These ranges are often defined by international standards, such as those from the International Electrotechnical Commission (IEC).

Test Setup:

The equipment under test (EUT) is connected to a testing apparatus that introduces controlled levels of conducted electromagnetic disturbances into the device’s power and signal lines.

The setup often includes a signal generator to produce the disturbance signal, coupling networks to inject the signal into the device, and measurement equipment to monitor the device's response.

 

 

Test Parameters:

  • Amplitude: The strength of the electromagnetic disturbance.

  • Frequency: The range of frequencies over which the disturbance is applied.

  • Duration: The length of time the disturbance is applied to the EUT.

  • Modulation: The pattern of how the disturbance is applied, which could be continuous or intermittent.


Test Procedure

  • The EUT is powered on and connected to the test setup. It is configured to operate in its normal mode, performing its intended function.

  • The test environment is controlled to minimize external interference.

  • The disturbance signal is generated and injected into the power and/or signal lines of the EUT. The frequency and amplitude of the signal are varied according to the test standard being followed.

  • The disturbance may be applied to multiple points in the system, including power inputs, signal inputs/outputs, and control lines.

  • The EUT is monitored for any signs of malfunction, degradation in performance, or failure. This can include observing changes in output signals, operational errors, or complete shutdown.

  • In some cases, the EUT’s internal parameters (e.g., voltage levels, temperatures) are also monitored to detect subtle effects of the conducted interference.

  • The results of the test are recorded, including any instances of failure or degradation. The data is analyzed to determine the susceptibility of the EUT to the conducted disturbances.

  • If the device fails to meet the required performance standards, it may need design modifications or additional shielding to improve its immunity.

  • A detailed report is generated, documenting the test conditions, procedures, results, and any recommendations for improving the device’s susceptibility performance.

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