There are clear cases of weapon system misfires related to surges or electrical anomalies. Missile launch systems are complexly composed of electrical signals, ignition control, and safety circuits. Abnormal electrical surges or electromagnetic interference (EMI) can increase the risk of malfunction, misfire, or even unexpected explosion.

 

Missile system misfires and electrical surges

• In the actual USS Forrestal (1967) accident, an electrical surge in the launch control circuit of an aircraft missile caused the unintentional launch of an armed rocket, resulting in a massive fire and casualties. The investigation concluded that the direct cause was a combination of the electrical surge, a missing safety pin, and a design flaw. These circuits are particularly vulnerable when switching between external power sources (ground to aircraft).

• In missile and aircraft weapon ignition circuit design, EMI filters, safety switches, and redundant safety devices (interlocks) are essential for blocking electromagnetic interference (EMI) and abnormal electrical signals. The military missile industry uses high-performance EMI filters to prevent misfires and malfunctions caused by these electrical anomalies.

 

Additional Cases Related to Military Misfire Accidents

• In actual aircraft and missile launch systems, malfunctions and misfires due to electrical causes such as surges, external electrical interference, and poor grounding of the approach system have been reported.

• It was noted that the 2019 Chuncheon Cheongung missile mislaunch was being investigated as a possible cause of an electrical control circuit malfunction or equipment failure during maintenance. Surges or abnormal signal inputs are suggested as possible causes of this incident.

 

International examples

• NASA's Kennedy Space Center Launch Complex-39B uses a 600-foot lightning arrestor and a network of steel cables to collect lightning strikes and channel them to the ground, directly protecting missiles and facilities. The system suffered no damage even in an actual lightning strike.

• In the case of European space launch sites, system safety is ensured even against lightning strikes and surges of the highest intensity through mesh cages, grounding nets, and appropriate lightning rod spacing in accordance with the IEC62305 standard.

In summary, surge protection in missile launch systems requires the integrated application of multiple defense methods, including SPD installation, shielding, grounding reinforcement, EMI/EMC design, and circuit redundancy.

 

Surge protection for missile launch systems is achieved through a variety of technical methods and multi-layered protection system designs. These systems primarily aim to prevent malfunctions caused by lightning strikes, power system surges, communication line surges, and electromagnetic interference (EMI).

 

Key surge protection methods for missile systems

• Installing SPD (surge protector)

• Install SPDs (Surge Protective Devices) on missile launchers, control units, communication and data lines to prevent abnormal surge currents from flowing into sensitive electronic and control components.

• Shielding and equipotentialization

• Metal shielding or mesh cage structures and equipotential bonding minimize lightning or surge voltage leakage and prevent potential differences within the system. NASA, the European Space Launch Center, and others block lightning inflow paths with large shielding towers and cable networks.

• Strengthening bonding and earthing

• It forms an integrated low-impedance grounding network with all electrical devices, junction boxes, fuel tanks, and other external conductors, thereby quickly discharging any generated surge current to the ground.

• Install a surge monitoring system that can monitor incoming or induced surges by installing a device that monitors lightning and various surges.

 

EMI/EMC (Electromagnetic Interference/Compatibility) Countermeasures

• We install EMI (electromagnetic interference) filters, appropriate ferrite beads, and filtering circuits on cables, signal lines, and power lines, and strictly comply with EMC design standards at the system level.

• Redundancy and circuit protection

• The controller, ignition circuit, etc. are equipped with redundant safety design, insulation/constant voltage circuits, and overcurrent protection devices to protect the main system from abnormal surges.

 

Surge protection technology standards

MIL-STD-1275E

• Defines transient surge, spike, and reverse polarity immunity requirements for 28V DC-based military vehicles and munitions systems. Designs include specific specifications for 100V 50ms surge, ±250V 70μs spike, -65V reverse voltage tolerance, up to 34V under normal operation, and dual (two-stage) clamping circuitry.

 

UFC 3-575-01 / NFPA 780

• Lightning and electrostatic discharge protection standards for US military buildings and equipment. Complete guidelines for preventing lightning damage, including SPD installation, lightning protection, structural shielding, and grounding.

 

IEC/KS C IEC 61643-11

• This document defines the performance, withstand voltage, and testing methods of surge protection devices (SPDs). It also specifies requirements and installation rules for each class: main power (Type 1), distribution board (Type 2), and individual equipment (Type 3).

 

IEC 61000-4-5

• Transient voltage (surge) immunity test method, essential for ensuring immunity of systems and equipment.

 

IEEE C62.41

• Surge test waveforms for electrical equipment and electronic devices, surge immunity standards by class.

 

KEC/KS C IEC 61643-11

• Designed to be integrated with lightning protection systems and aligned with domestic electrical and defense industry SPD selection and installation regulations.