What is the role of surge protection devices in aircraft electrical systems?

• A. They clamp voltage surges to protect equipment
• B. They generate power during outage
• C. They provide EMI shielding
• D. They regulate battery charging

Answer: (A)

Surge protection devices protect by clamping voltage surges in aircraft electrical systems, keeping transient voltages from exceeding levels that equipment can safely tolerate. In flight, wiring can experience brief but intense spikes from lightning strikes, switching large loads, or faults in external power sources. SPDs provide a fast, low-impedance path for the excess energy, diverting it away from sensitive components and holding the voltage at a safe level. This limits insulation stress, arcing, and potential damage to avionics, sensors, and power electronics. They don’t generate power, shield against EMI, or regulate charging; their primary role is to absorb or redirect surge energy to protect the system.