Overview: EMP Protection

What is an Electromagnetic Pulse?

An electromagnetic pulse is a sudden burst of electromagnetic energy that radiates through the air close to speed of light. High-altitude Electro-Magnetic Pulses (HEMP) generated from both natural and intentional sources can cause disturbance and damage to ground based electrical systems, aircraft, and vehicles.

An electromagnetic pulse moves extremely fast so it generates a tremendous amount of electricity in metal objects it passes through. This is one of the reasons the lights sometimes go out near a lightning strike. A solar flare, nuclear explosion, lightning strike and such events can cause a major blast of electromagnetic energy that spreads out in all directions.

HEMP filters are designed to protect specific electrical assemblies, or sub-assemblies from HEMP Pulses. The EMP/HEMP filters protect electronics equipment by absorbing the potentially destructive EMP voltage and current within the filter before it reaches the electronic devices. Without protection from this harmful EMI, damage and disruption to system operability can be catastrophic, causing not only loss of data, security, connectivity or even loss of life.

What are the different pulse types of EMP?

The HEMP is typically defined as a combination of three consecutive pulses:

Short Pulse (E1) : Generates a brief but high energy electromagnetic field. Induces extremely high voltages as it couples with electrically conductive structures. Responsible for the most damage in any HEMP event. High voltages causes the electrical breakdown in devices and components.

Intermediate Pulse (E2) : Generated by scattered gammas and by "neutron scatter gammas". Similar to a conventional lightning strike. Approximately a few microseconds to one full second. EM energy generated by the E2 pulse is not nearly as intense as E1.

Long Pulse (E3) : similar to the geomagnetic disturbances (GMDs). E3 component, lasting from tens of seconds to minutes in duration. Potential to impact the operation of power grid transformers, relays.

HEMP protection methods and standards

HEMP Hardening : Critical electronic equipment is hardened using a shielded metallic enclosure to block electromagnetic fields, known as the Faraday Cage. This helps to bypass the damaging electromagnetic fields away from critical equipment. Electric charges of conducting material are distributed such that they cancel the field's effect in the cage's interior.

Point of Entry (POE) solutions : HEMP Energy may enter the shielded room if not protected at the Point of Entry (POE). Point of Entry is the location where the shield is penetrated. All POEs of the Faraday cage have to be protected from EM fields. HEMP Filters are incorporated on the chambers for this. Critical systems may also be protected by increasing the number of backup units.

EMP/HEMP filters are designed to comply with the following performance and safety compliance standards (Military and Commercial):

  • MIL-STD-188-125-1 & -2
  • IEC 61000-4-24
  • MIL-F-15733
  • MIL-STD-220
  • UL 1283
  • IEC 60939
  • LVD (2006/95/EC)

What EMIS offers

EMISINDIA has a strong presence in solutions for HEMP (High altitude Electromagnetic Pulse). Customer specific solutions are also delivered on request, apart from filters and shielding solutions from the EMIS product catalog . High reliability, MIL- grade EMI Filters solutions not only provide one of the smallest footprints available in the market, but also the added flexibility of widely ranging interconnect options for ease of integration into existing systems. Comprehensive EMC/EMI Testing and EMI Consultancy services can also be availed to meet various industry and military standards.

  • Solutions for all 3 types of EM Pulses (E1: 5kA 20/550ns pulse, E2: 250A 1.5┬Ás/4000ms pulse, E3: 1000A 0.2/20s pulse)
  • Can handle natural and man-made events such as Nuclear explosions (Intentional) or Solar Flare or Geomagnetic storm (Natural)
  • Architectural, Mechanical and Structural solutions for POE
  • Electrical POE Components for protection from HEMP
  • Compliance to MIL STD-188-125-1/2 and IEC 61000-4-24 standards for HEMP protection
  • All the series of POE are tested for the relevant standards
For MIL-STD-188-125-1 reference - Injected pulse characteristics and residual internal stress limits for classes of electrical POEs
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