MIL-STD-188-125-2: High-Altitude Electromagnetic Pulse Protection For Ground-Based C4I Facilities

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

Keystone’s EMC and shielding effectiveness testing capabilities can meet even the most difficult and unique test levels. With seven EMC chambers and multiple workstations, we provide extremely short lead times on scheduling. Additionally, 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.

Summary of MIL-STD HEMP Compliance Testing

The MIL-STD-188-125-2 standard evaluates a system’s ability to comply with high-altitude electromagnetic pulse (HEMP) hardening of transportable ground-based systems. These systems have features of time-urgent command, control, communications, computer, and intelligence missions.

Specifically, this is a series with a companion specification of MIL-STD-188-125-1, with the only difference being that this specification addresses only transportable systems. Whereas MIL-STD-188-125-1 addresses fixed facilities. In other words, this addresses the minimum requirements for showing a predetermined performance has been achieved and for verifying installed protection measures provide operationally required HEMP for the completed system.

System examples include, and are not limited to, subscriber terminals and data processing centers, transmitting and receiving communications stations, and relay systems under the assumption that long-haul communications paths, fiber optic links, or other hardened interconnects between systems are provided as required as such in the field.

These relate to transportable systems such as electrical shielding enclosures or fixed rooms in buildings. However, this is as long as the unit fulfills the sole purpose of the specification. The owner will determine if the observed event is mission aborting.

The test setup is the same as other shielding effectiveness, with the determination of the dynamic range and the actual measurement of the signal for the sample in question. If the system involves a weapon enclosure, all internal components need removed such that only the enclosure is being tested.

Scope of MIL-STD-188-125-2 Regulatory Compliance

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 are 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. Furthermore, HEMP hardness is achieved through adhering to appropriate design specifications and is verified by one or more test and analysis techniques.

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 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.

Pulsed current injection (PCI) is a test method for measuring the 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 is a test 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 operating 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.

Expert MIL-STD-188-125-2 Compliance Lab

Keystone Compliance has the capabilities to test any size enclosure to MIL-STD-188-125-2. We have tested large items such as entire on-site installation buildings and small items that can be easily transported to our lab. Thus, our accurate test reports are delivered quickly to avoid product launch delays.

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.

Are you ready to partner with Keystone Compliance to determine the shielding effectiveness of your product when tested to the requirements of MIL-STD 188-125-2? Let’s get started!