EMI-EMC Tests

EMI EMC tests have majorly two categories: Emission and Immunity
 

​1. EMI (Electromagnetic Interference) Tests

These tests measure the electromagnetic energy emitted by a device to ensure it does not exceed permissible limits.

a. Conducted Emission Testing

  • Measures unwanted electromagnetic energy conducted through power or signal lines.

  • Test is performed using a Line Impedance Stabilization Network (LISN).

  • Frequency range: 150 kHz to 30 MHz (typical).

 

b. Radiated Emission Testing

  • Measures electromagnetic energy radiated through the air by the device.

  • Performed in an anechoic chamber or open-area test site (OATS).

  • Frequency range: 30 MHz to several GHz.

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c. Harmonics and Flicker Testing

  • Measures the emission due to the unbalanced load and switching of the components.

  • Relevant for grid-connected equipment.

 

2. EMC (Electromagnetic Compatibility) Tests

These tests ensure that a device can operate correctly in its electromagnetic environment without interfering with other devices.

a. Conducted Immunity Testing

  • Evaluates the device’s immunity to electromagnetic noise on power or signal lines.

  • Test involves injecting RF signals (150 kHz to 230 MHz) using a coupling device.

 

b. Radiated Immunity Testing

  • Ensures that the device can function correctly under exposure to radiated electromagnetic fields.

  • Test frequency range: 80 MHz to several GHz.

 

c. Electrostatic Discharge (ESD) Testing

  • Simulates static electricity discharges to verify device robustness.

  • ESD simulators are used to test contact discharge (direct) and air discharge (indirect).

 

d. Electrical Fast Transient/Burst (EFT) Testing

  • Evaluates the immunity of devices to fast, repetitive bursts of electrical energy.

  • Typically tests power lines, signal lines, and I/O ports.

 

e. Surge Immunity Testing

  • Simulates high-energy transient surges, such as lightning strikes or power line switching.

  • Tests conducted on power and communication lines.

 

f. Power Frequency Magnetic Field Testing

  • Verifies immunity to magnetic fields from power lines or industrial equipment.

  • Typical frequency: 50 Hz or 60 Hz.

 

g. Voltage Dips, Interruptions, and Variations Testing

  • Simulates power supply disturbances to check the device's behavior.

  • Tests short-term power interruptions and voltage dips.

 

3. Specialized Tests

These tests apply to specific industries or advanced devices.

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a. Cross-Talk Testing

  • Measures interference between closely spaced conductors or circuits.

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b. Reverberation Chamber Testing

  • Exposes the device to multiple electromagnetic waves to test robustness in a reflective environment.

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c. TEM Cell Testing

  • Used for small devices to simulate a controlled electromagnetic field for emissions and immunity.

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