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MIL-STD-188-125-2 HEMP Protection for Ground-Based Transportable Systems

As a leader in shielding effectiveness and HEMP testing, Keystone Compliance has the expertise and capabilities to meet any test need. From the creation of test plans to the issuance of test reports, we guide manufacturers through the entire process.

Our EMC and shielding effectiveness testing capabilities can meet even the most difficult and unique test levels. With seven EMC chambers and multiple work stations, we provide extremely short lead times on scheduling. Our ISO-17025 accredited test reports are completed quickly and accurately and accepted around the globe.

To learn firsthand why so many companies partner with Keystone Compliance to meet their HEMP testing and shielding effectiveness test needs, Contact Us or Request a Quote. The remainder of this page speaks to the MIL-STD-188 125-2 test standard.

The official title of MIL-STD-188-125-2 is: High-Altitude Electromagnetic Pulse (HEMP) Protection for Ground-Based C4I Facilities Performing Critical, Time-Urgent Missions. The Part 2 is in reference to transportable systems.

The purpose of the test standard is to establish the minimum requirements and design objectives for high-altitude electromagnetic pulse (HEMP) hardening of specific systems. These systems are transportable ground-based systems that perform critical, time-urgent command, control, communications, computer, and intelligence (C4I) missions.

Systems required to fully comply with the provisions of the standard will be designated by the Joint Chiefs of Staff, a Military Department Headquarters, or a Major Command. The scope of MIL-188-151-2 is to specify the minimum performance requirements for low-risk protection from mission-aborting damage or upset due to HEMP threat environments defined in MIL-STD-2169.

The standard also addresses minimum testing requirements for verifying that the installed protection measures provide the operationally required HEMP hardness for the completed system. If the prescribed testing results in any hardware damage or functional upsets, the operational authority for the system will make the determination whether the observed event is mission aborting.

MIL-STD-188-125-2 HEMP testing defines the design and testing criteria for specifically designated transportable ground-based systems in HEMP-hardened, critical, time-urgent C4I networks. These systems include subscriber terminals and data processing centers, transmitting and receiving communications stations, and relay systems.

The standard applies to both new systems and modifications of existing systems. Although only local portions of system interconnects are addressed, it is assumed that survivable long-haul communications paths, fiberoptic links, or other hardened interconnects between systems will be provided as required for mission accomplishment.

Ultimately, the objective is survivable C4I capabilities. These systems are essential to a credible military deterrent. This standard supports nuclear survivability objectives by providing a standardized, low-risk protection approach for transportable ground-based systems in HEMP-hardened C4I networks. These uniform requirements ensure balanced HEMP hardening for all critical systems and facilities in the network.

To understand this shielding effectiveness EMC test standard, it is important to understand some of the more commonly used terms. Included in the following paragraphs are some definitions that better explain some of the terminology of this testing.

HEMP acceptance testing can be performed on a system, subsystem, or component. These tests are performed to ensure that specified HEMP performance characteristics have been met. HEMP acceptance tests are typically conducted near the conclusion of a hardening production or installation contract. These tests for the purpose of demonstrating that at least minimum performance requirements of the HEMP protection measures have been achieved before the unit is accepted by the Government from the contractor.

HEMP hardness is a quantitative description of the resistance of a system or component to temporary or permanent malfunction or degraded performance induced by HEMP. HEMP hardness is achieved through adhering to appropriate design specifications and is verified by one or more test and analysis techniques.

A HEMP hardness critical item (HCI) is an item at any assembly level having performance requirements for the purpose of providing HEMP protection. Nuclear HCIs provide protection from environments produced by a nuclear event or are specially designed to operate under nuclear weapon (device)-derived stresses. HEMP HCIs are the elements of the HEMP protection. A hardness critical assembly is a top-level definable unit of HEMP HCIs and other components, such as mounting hardware and terminal posts, that may not be hardness critical.

A Pulsed current injection (PCI) is A test method for measuring performance of a point of entry protective device on a penetrating conductor. A HEMP threat-relatable transient is injected on the penetrating conductor at a point outside the electromagnetic barrier, and the residual internal transient stress is measured inside the barrier.

Verification testing. Tests conducted for demonstrating that the installed HEMP protection measures provide the required HEMP hardness. These tests are performed after the production and acceptance testing are complete and after the equipment is installed and functioning, to determine if the operational system suffers mission-aborting damage or upset due to simulated HEMP excitations. Verification is normally a Government-conducted test and is not part of a system production contract.

As previously mentioned, Keystone Compliance is regarded as one of the best HEMP testing labs in the country. We understand that the need exists for uniform and effective hardening, hardness verification, and hardness maintenance/hardness surveillance of transportable ground based C4I systems.

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