Simulating Fire Scenarios within an Anechoic Chamber

In closed and climate-controlled spaces, such as an EMC chamber, heat spreads particularly quickly in the event of a fire. A key challenge is assessing the heat input into the space caused by the burning test object (DUT). While common fire protection concepts exist for enclosed spaces, the heat resistance of EMC absorbers in EMC chambers presents a particular challenge, as conventional absorber materials often have low heat absorption capacity and therefore react sensitively to heat exposure.

The fire simulation specifically aims to determine the maximum temperatures at various points in the EMC chamber on walls, ceilings, and near the test specimen. This allows an assessment of the extent to which the absorbers are at risk of overheating from the heat input and potentially igniting.

Information about heat load of different DUT's:

• 1 MW = small size DUT (multimedia products, e.g., television)
• 5 MW = medium size DUT (industrial products, e.g., refrigerator)
• 10 MW = large size DUT (automotive products, e.g., passenger car)

Fire simulations can provide valuable insights into the effectiveness of existing fire safety systems, such as water fog fire extinguishing systems, and highlight the need for additional measures.

The absorber materials used in these chambers to attenuate electromagnetic waves are typically sensitive to high temperatures and carry a potential fire risk. In the event of a fire, these materials cannot only contribute to the spread of heat but may also release toxic gases (e.g., HCN), further endangering personnel safety.

By using fire simulations for EMC chambers, companies can ensure both the quality of testing and that safety standards for employees and infrastructure are optimally met. A fire simulation demonstrates that both the heat input from the test object (DUT) and the size of the EMC facility significantly impact thermal stress. Smaller facilities heat up considerably faster than larger ones, especially with high-power equipment like a mid-sized vehicle. The following recommendations can be derived from simulation results:

? Optimization of absorber materials: To reduce thermal stress on critical surfaces, heat-resistant materials should be used. Unwanted side effects, such as the outgassing of hydrogen cyanide, should also be considered.

? Efficient fire protection systems: Installing fire protection systems specifically designed for the temperatures and unique requirements of EMC testing facilities is essential.

? Additional measures: Effective heat dissipation can be achieved through controlled airflow and targeted cooling techniques.

? Regular monitoring and maintenance: Continuous monitoring of facility components is essential to avoid safety risks.

Simulating fire scenarios makes it possible to develop preventive measures tailored to the unique conditions of an EMC chamber.

Some examples of the heat distribution into an EMC chamber environment caused by an burning (overheated) object.

Example 1:

SAC-3, mid-size DUT (5 MW), after 3 minutes about 500°C heat at absorbers on walls and ceiling (no absorbers illustrated)

Example 2:

SAC-10, large DUT (10 MW), after 3 minutes about 350°C heat at absorbers on walls and ceiling (no absorbers illustrated)

Conclusion

The heat handling of absorber materials gets a significant importance to ensure a safe environment.

Absorber Selection Criteria's

Selecting the right EMC absorber material for an EMC (Electromagnetic Compatibility) anechoic chamber is crucial for achieving optimal performance in electromagnetic testing.

Here are key parameters to consider:

? Frequency range

? Absorption performance

? Material type and classification

? Space constraints and physical dimensions

? Environmental sustainability and fire safety (for the invest and staff)

? Power handling capacity (heat handling)

? Durability and maintenance (long-term)

? Cost and budget

? Compliance with standards

Each EMC chamber will have its specific requirements based on the testing application, so carefully matching absorber material to these parameters is essential.

Further details about fire and heat simulation and getting the right argument to invest in your safe environment, just contact us.

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