NEMA Type 6 Meets EMI/RFI

NEMA Type 6 Meets EMI/RFI

Whether you’re in the defense space or a private industry such as energy or mining, protecting your valuable and sensitive equipment is vital. This includes combating water, dust and impact damage. A NEMA Type 6 enclosure can help with this.

But when your equipment is at risk of electromagnetic interference (EMI), such as radio frequency interference (RFI), your cabinet will need to provide EMI protection, too.

The Threat of Water, Dust and Electromagnetic Interference

EMI protection allows you to reliably operate sensitive equipment in electromagnetic environments. Without this protection, EMI could cause:

  • Distorted audio and video signals.
  • Interference with monitoring and control systems, such as GPS and RADAR.
  • Trouble establishing a wireless connection with your equipment.
  • Overheating and other malfunctions in your equipment.

However, the typical NEMA Type 6 protection is equally important. Without this protection, your equipment will be vulnerable to water ingress mechanisms, such as rain, spray, wave impact and temporary submersion, plus various types of dust intrusion, like fine particle dust found in the desert or salt aerosols commonly found around salt water.

Dust intrusion and water ingress mechanisms can cause abrasive wear on moving parts, vent and seal clogging, and galvanic corrosion between dissimilar metals.

To avoid these problems, your equipment must be protected from EMI interference, water ingress and dust intrusion. Otherwise, you risk mission failure, expensive equipment replacements and an increased maintenance burden.

When Are EMI-Protected NEMA Type 6 Enclosures Needed?

EMI-protected NEMA Type 6 enclosures are primarily required when equipment must reliably function in environments with external frequencies or noise, dust, extreme heat or water. Saltwater is particularly dangerous to sensitive equipment thanks to its corrosive nature, making coastal EMI protection important in many offshore electronics enclosures.

The defense, energy and mining industries often use sensitive equipment in these types of environments, and so require EMI-protected and reliable equipment. To operate compliantly and safely, many organizations within these industries have to meet particular standards, such as the following:

  • MIL-STD-167
  • MIL-STD-461
  • MIL-STD-810
  • MIL-STD-901
  • MIL-SPEC-285
  • NEBS TR 63
  • TEMPEST
  • FCC Part 15
  • European VDE

How to Ensure Your Cabinet Meets Every Need

To meet both NEMA Type 6 and EMI shielding requirements, your cabinet has to meet several standards. To receive verification, your cabinet must undergo:

Submersion Testing

To receive NEMA 6 rating, a watertight shielded cabinet must protect its contents when submerged at a depth of 6 feet for 30 minutes, even when ice has formed on its surface.

Similarly, an IP68 EMI enclosure must withstand at least 30 minutes of submersion at a depth of at least 1 m, as part of the IP68 testing.

Shielding Effectiveness Testing

To meet MIL-STD-461 standards, the cabinet must undergo several tests, which can cover:

  • Radiated emissions.
  • Conducted emissions.
  • Radiated susceptibility.
  • Conducted susceptibility.

These tests are conducted at various frequencies to ensure the cabinet performs across diverse environments.

To meet TEMPEST standards, the cabinet must undergo further testing, during which specialist equipment attempts to reconstruct sensitive information from signals emitted by the cabinet. This equipment is set at 1 m, 20 m and 100 m from the cabinet, with various frequencies and orientations being tested.

Vibration Testing

 

MIL-STD-167 helps to ensure that enclosures can perform when exposed to prolonged vibrations, such as those experienced by shipboard RADAR on a naval vessel.

Environmental testing ensures the marine EMI cabinet can function well when exposed to constant and steady vibrations. Ranging from 4 Hz to 33 Hz, the cabinet must undergo triaxial vibration testing for up to two hours at a time without showing signs of damage or impairment.

Durability Testing

To ensure the cabinet can operate in harsh conditions, MIL-STD-810 testing assesses its performance under 28 extreme conditions. The cabinet’s performance may be tested under various atmospheric conditions, such as:

  • Low pressure.
  • High and low temperatures.
  • Temperature shock.
  • Fluid contamination.
  • Solar radiation.
  • Rain and humidity.
  • Salt fog.
  • Sand and dust.

The cabinet may also be tested to see how it performs when it experiences several types of physical stress, such as gunfire shock, ballistic shock, acoustic noise, vibration, immersion and acceleration.

Why Many NEMA Type 6 Enclosures Don’t Provide EMI Protection

NEMA Type 6 enclosures protect electronic equipment from water, dirt and other foreign objects. However, many do not provide EMI protection due to the challenges of constructing an enclosure that meets all requirements and the additional cost this entails. NEMA Type 6 enclosures must be carefully engineered to meet the required standards, as must EMI-protected enclosures.

Creating enclosures that meet all standards and engineering technical requirements can be challenging. For example, the conductive metals commonly used in EMI shielding can experience galvanic corrosion when they become wet, which is possible due to the wet environments in which NEMA Type 6 enclosures are commonly used. Additionally, the typical NEMA 6 gasket materials aren’t suited to EMI shielding.

Any access points in the enclosure must also maintain both the NEMA 6 seal and the EMI shield, which requires specialized cable glands, conductive gaskets and shielded windows. These components must all:

  • Be watertight and dust-tight when under compression.
  • Maintain electrical conductivity through environmental exposure.
  • Resist galvanic corrosion when interfacing with dissimilar metals.
  • Prevent dust accumulation that could compromise seal integrity.

Creating NEMA Type 6 Enclosures With EMI Protection Using Dual-Function Materials and Designs

For an enclosure to provide EMI, water and dust protection, certain materials and design changes must be implemented into the enclosure’s gasket.

To ensure the conductive elastomers maintain conductivity and an environmental seal, silver- or nickel-filled silicone is regularly used. A knitted stainless steel or monel mesh is also placed over the elastomer core to increase resistance to salt fog, while also providing a watertight and dust-tight seal. Beryllium-copper or stainless steel fingerstock is also nested in the gasket.

The installation and bonding must also:

  • Have a continuous perimeter around the gasket.
  • Ensure any splices overlap and are compression-bonded.
  • Have bonding at every fastener.

The enclosure must also meet the active cooling requirements of electronic equipment without compromising the environmental seal or causing thermal expansion.

To achieve this, manufacturers can use a honeycomb structure in the air vents that facilitates safe airflow. Additionally, vent cells can be backed by a hydrophobic membrane to prevent water and dust ingress. Finally, the enclosure can be cooled through internal heat exchangers.

Benefits of EMI-Protected NEMA Type 6 Enclosures

Beyond helping you achieve compliance and protecting your equipment and data, NEMA Type 6 enclosures with EMI protection can provide many other benefits, such as:

  • Reduced downtime: Protecting your equipment from extreme temperatures, water and other dangers helps it to consistently operate efficiently and reduce downtime.
  • Enhanced equipment longevity: By protecting your equipment from potential damage, you increase its lifespan.
  • Increased operational safety: Fully functioning equipment reduces the risk of electrical hazards, as well as incorrect data readings.
  • Reduced costs: Enhanced equipment longevity, lower maintenance costs and reduced downtime can all result in lower costs.
  • Enhanced data: By preventing data from being interfered with, EMI protection leads to more reliable and higher-quality data and communications.

Why Trust Equipto Electronics Corp?

At Equipto Electronics Corp, our cabinets are always tailored to your needs, whether that’s by customizing a standard model or custom-making a cabinet based on your specifications. We’ve been creating modular cabinets since 1960, and in that time, we’ve been trusted by organizations in various industries, from government and the military to energy and utilities.

Our experience and dedication to delivering a comprehensive solution mean that all of our NEMA Type 6 cabinets provide EMI protection. We can also build each enclosure to comply with several key standards. What’s more, we’ll share test reports on our products so you can see the results for yourself before you buy.

Protect Your Equipment With Custom Cabinets From Equipto Electronics

Whatever environment you need to use your electronics in, Equipto Electronics can help you protect your equipment as you do so. Whether you need a shipboard watertight rack, a full-size enclosure or a cabinet built to your specifications, we build every option with performance in mind.

To find out more about how our custom EMI-protected NEMA Type 6 cabinets can meet your needs, contact us today.