MIL-STD 188-125-1 evaluates low-risk protection from mission-aborting damage due to HEMP attacks. The description of these threats are defined in MIL-STD-2169. MIL-STD-188-125-1 also addresses requirements for demonstrating that prescribed performance has been achieved. The military standard verifies that the installed protection subsystem provides the operationally required hardness for the completed facility.
The MIL-STD-188-125-1 test standard defines the design and testing criteria. Specifically designated for fixed ground-based facilities in HEMP-hardened, critical, time-urgent C4I networks. Facilities include subscriber terminals and data processing centers, transmitting and receiving communications stations, and relay facilities. MIL-STD-188-125-1 applies to both new construction and the retrofit of existing facilities.
Local portions of facility interconnects are addressed. However, it is assumed that survivable long-haul communications paths, fiber optic links, or other hardened interconnects between facilities may be required to pass. MIL-STD-188-125-1 can also be used for HEMP protection of other ground-based communications-electronics facilities that require HEMP hardening.
Scope of the Military Standard Test Method 188-125-1
To gain a better understanding of the requirements, it is important to understand the specific terminology used in HEMP testing.
Electromagnetic stress is a voltage, current, charge, or electromagnetic field that acts on a piece of equipment. If the electromagnetic stress exceeds the vulnerability threshold of the equipment, mission-aborting damage or upset may occur.
Facility HEMP shield is the continuous conductive housing that substantially reduces the coupling of HEMP electric and magnetic fields into the protected volume. The facility HEMP shield is part of the electromagnetic barrier.
HEMP hardness surveillance/re-verification testing is testing conducted at prescribed intervals during the operational phase of the facility life cycle. This testing is for evaluating whether the HEMP protection measures continue to provide the required HEMP hardness. HS/re-verification test requirements are established in the technical manual.
A main barrier electrical POE protective device is a protective device installed on an electrical conductor that penetrates from the system exterior, through the HEMP shield, and into the protected volume. Main barrier protective devices must meet the performance requirements of this standard.
A special protective volume is a HEMP-protected space within the facility, where electromagnetic stresses due to HEMP may exceed the residual internal stress limits for the protected volume. The special protective barrier may be a separate shield with protected penetrations. These are more commonly, shielded cables or conduits, and equipment cabinets and closed piping systems are used to provide the needed electromagnetic isolation from the protected volume.
The vulnerability threshold (of an equipment) is the minimum stress level that causes the equipment to suffer definite damage or performance degradation. In the context of this standard, the vulnerability threshold is the minimum electromagnetic stress that causes mission-aborting damage or upset.
Expert HEMP Military STD-188-125 Compliance Testing
Keystone Compliance has completed numerous site surveys to determine the level of protection against HEMP attacks. Our team diligently completes the assessments and provides valuable feedback on any weaknesses that should be addressed. This feedback often includes suggestions for remediating any aperture points of entry (POE) and conductive points of entry.
Lastly, our experience provides insight on improving protection as well as in determining specific locations within the facility that be more likely to serve as a point of entry.