28V

28V refers to a nominal electrical potential of 28 volts in direct current (DC) power systems. It is a standard commonly used in aerospace, military, telecom, automotive, and industrial equipment to power avionics, sensors, actuators, control systems, and other loads. The term describes the nominal level; actual voltages in operation can vary within specified tolerances and transient conditions.

In aviation and aerospace, the 28V DC system has been a long-standing standard for primary electrical power. It is typically supplied by onboard batteries and power sources such as generators or alternators, and it distributes to a wide range of equipment through protected buses and regulators. Nickel‑cadmium batteries have historically been associated with 28V systems because of their robustness and high discharge rates, although newer aircraft may employ alternative chemistries such as lithium-based batteries for weight and performance benefits. The bus voltage is nominally 28V, with operating ranges commonly defined to accommodate charging, start transients, and load changes.

Electrical protection and regulation are important aspects of 28V systems. Circuit protection devices, such as fuses and circuit breakers, are used to prevent overcurrent conditions. Power conversion stages, including DC-DC converters, provide lower voltage rails for avionics and control electronics. Standards and specifications governing 28V air systems include aerospace power requirements and environmental testing, which address voltage tolerance, surge handling, electromagnetic compatibility, and reliability.

Beyond aviation, 28V DC is also used in some military vehicles, industrial equipment, and telecommunications infrastructures, where higher voltage at low current improves efficiency and reduces conductor size compared with lower-voltage systems. The 28V designation remains a practical label for a widely adopted, high-availability DC power level.