Shielding at power frequency using femlab

In summary, the conversation discusses using femlab for 2D modeling of shielding at power frequency, specifically using reinforcement bars at 45 degrees instead of 90 degrees for better shielding efficiency. The topic also touches on when multiple reinforcement bars are used instead of a full shield in a room, typically for EMI and RF testing in a frequency range of a few 100kHz to a few GHz.
  • #1
sanshyme
4
0
Hi

I am doing shielding at power frequency using femlab. i have done 2D modeling on a room using reinforcement bars instead of a full shield and i wonder why is the bar inclined at 45 degrees will give a better shielding effeciency than at 90 degree?

in the real world, when do we use multiple reinforcement bars instead of a full shield in a room?

thanks
serene
 

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  • #2
Must be some quirk of the simulation program. Does it let you plot shielding effectiveness as a function of the radiation's angle? It sounds like your shielding simulation for "power frequency" is for 50-60Hz, right? That's not typically what I've seen shielded rooms used for. The shielded rooms and anechoic chambers that I've been in are for EMI and other RF testing work. The frequency range of interest where the room has to have very good shielding integrity is typically from a few 100kHz up through a few GHz. You only get that with a full shield room, including conductive gasketing on all openings like doors and cable feed-through ports.
 
  • #3


Hello Serene,

Thank you for sharing your work on shielding at power frequency using femlab. To answer your question, the inclination of the reinforcement bars at 45 degrees is based on the concept of Faraday's cage. This principle states that a conductive material can block electromagnetic fields by redirecting them around the enclosed space. When the reinforcement bars are inclined at 45 degrees, they create a "cage" around the room, allowing the electromagnetic fields to be redirected along the bars instead of entering the room. This increases the shielding efficiency compared to bars at 90 degrees, which would allow for more field penetration.

In the real world, multiple reinforcement bars are often used instead of a full shield when cost or space constraints are a concern. Using multiple bars allows for a similar shielding effect while using less material and taking up less space. Additionally, in some cases, reinforcement bars may also be used for structural support, making them a dual-purpose solution. However, it is important to note that a full shield will always provide the highest level of shielding efficiency.

I hope this helps answer your questions. Keep up the good work on your project!

 

What is femlab?

Femlab is a software tool used for designing and simulating electromagnetic fields in various applications, including shielding at power frequency.

Why is shielding necessary at power frequency?

Power frequency refers to the frequency at which electricity is transmitted through power grids, which is typically 50 or 60 Hz. At this frequency, electromagnetic fields can be harmful to human health and can interfere with sensitive electronic equipment. Shielding is necessary to reduce the exposure to these fields and prevent interference.

How does femlab help with shielding at power frequency?

Femlab uses numerical methods, such as finite element analysis, to model and simulate electromagnetic fields in different scenarios. This allows engineers and scientists to design and optimize shielding solutions for specific power frequency applications.

What are the key factors to consider when using femlab for shielding at power frequency?

The key factors to consider include the materials used for shielding, the geometry and design of the shielding, the placement of the shielding in relation to the power source, and the desired level of attenuation (reduction of electromagnetic fields).

Are there any limitations to using femlab for shielding at power frequency?

While femlab is a powerful tool for simulating electromagnetic fields, it is important to note that it is a numerical approximation and may not always accurately reflect real-world conditions. It is also important to have an understanding of electromagnetic field theory and the limitations of the software in order to properly interpret the results and make informed decisions about shielding design.

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