MIL-STD 188-125

Hardness Maintenance, Hardness Surveillance

Throughout the lifecycle of HEMP Shielded enclosures, protection failures or degradation may go unnoticed until critical operations must be performed. Therefore, it is necessary for surveillance of the HEMP protected system to maintain mission readiness and HEMP Hardness throughout the life cycle of the system. Inspection, preventative maintenance, testing, and repairs will extend the operational life cycle and efficacy of the HEMP hardened system while ensuring sufficient protection of critical infrastructure during time sensitive operations. Gaven Industries will lead the charge in the identification of all Hardness Critical Items, and Hardness Critical Processes, as well as physically conducting the suggested maintenance practices.

Shielding Effectiveness Image

Shielding Effectiveness

MIL-STD-188-125 Shielding Effectiveness (SE) Testing

In order to confirm compliance with MIL-STD-188-125 Pulse Current Injection Testing, shielding requirements and gain confidence that critical infrastructure will remain undamaged throughout and after an EMP event, Shielding Effectiveness testing is conducted. Shielding effectiveness testing assesses the shielded enclosure’s ability to block harmful electromagnetic and radio frequency signals. Given Gaven’s decades of experience, efficiencies have been identified through the development of test methodologies and practices, allowing Gaven to accelerate the testing process without sacrificing quality. Gaven offers both Acceptance and Verification Shielding Effectiveness Test Services
Acceptance Shielding Effectiveness Testing (ASE) is conducted immediately after the construction of a shielded enclosure is completed, and all point-of-entry protective devices have been installed. This testing is conducted to confirm proper construction, manufacturing, and installation techniques were followed, and that the Shielded Enclosure meets all attenuation requirements.
Verification Shielding Effectiveness Testing (VSE) is conducted after mission-critical equipment has been installed in the shielded space and the infrastructure is able to operate. This testing is necessary to confirm that the integrity of the shield was not compromised during the installation of critical infrastructure and associated wiring.


Often power and signals need to enter and exit HEMP protected facilities/shields. Externally generated threat energies can couple onto these lines and may enter the shield through the installed filters. PCI is a test method for measuring performance of a point-of-entry (POE) protective device on a penetrating conductor. A HEMP threat-relatable transient is injected on the penetrating conductor at a point outside the electromagnetic barrier/shield, and the residual internal transient stress is measured inside the barrier/shield.

Gaven Industries has performed pulsed current injection (PCI) testing on thousands of electrical point-of-entry protection devices (PPDs) in accordance with Appendix B of MIL-STD-188-125-1 and -2 (fixed and transportable).

Gaven has designed and manufactured pulse generators capable of outputting MIL-STD-188-125-compliant double-exponential waveforms. These pulse generators output short pulse (E1) current injections up to 5 kA as well as intermediate pulse (E2) current injections up to 250 A. Gaven routinely tests power filters, audio filters, data filters, control/signal filters, as well as RF lines.

Gaven has invested in the development of proprietary software that automates the control of pulse generators, data acquisition, and real-time data analysis. This software streamlines the PCI testing process and provides graphical data moments after injection.

Acceptance PCI (APCI) testing is performed at our facility in Saxonburg, PA immediately after receipt to ensure HEMP Filters (PPDs) meet the residual norm requirements detailed in MIL-STD-188-125. This approach limits schedule risk, as performance issues are identified/rectified at the earliest time possible.

Verification PCI (VPCI) testing is typically performed on-site at the customers’ facility after critical infrastructure/mission-critical equipment (MCE) has been installed. During VPCI testing, PPDs are analyzed to confirm compliance with MIL-STD-188-125. Customers are also provided the opportunity to monitor MCE to ensure mission completion, while simulated HEMP transients are applied to power, control, signal, and RF circuitry.

Testing Services HEMP Image
Testing Services HEMP Image