Unitron UDC-420M 28V DC Aircraft Rectifier (GPU)

The Unitron UDC-420M is compatible with a wide range of fixed-wing and rotary-wing aircraft that require a 28V DC external power source. It’s designed to support general aviation, business jets, regional airliners, and military aircraft during ground operations, such as maintenance and avionics testing. The unit’s regulated output and ripple-free current ensure safe operation for modern electronic systems and sensitive onboard equipment.

The UDC-420M provides instantaneous 28V DC power, eliminating the need for the aircraft’s internal batteries and allowing maintenance crews to perform avionics testing, system calibration, and engine starts more efficiently. It reduces battery discharge cycles, extending battery life and minimizing maintenance downtime. The consistent voltage output also ensures optimal system diagnostics during preflight and post-maintenance procedures.

Safety is integral to the UDC-420M’s design. The unit features overvoltage, overcurrent, and short-circuit protection, as well as emergency shutdown capabilities. Its robust electrical insulation and compliance with UL, CE, and MIL-STD safety standards ensure operator safety and protection for sensitive aircraft systems during use.

Yes. The UDC-420M carries the CE marking, confirming compliance with European Union directives for safety, health, and environmental protection. This certification ensures that it meets international aviation maintenance standards, making it suitable for use by MROs, FBOs, and operators worldwide.

The UDC-420M is designed with towable portability in mind, featuring a durable chassis with nonmarking pneumatic tires and a foldable tow handle for easy maneuvering across hangar floors and ramps. Its compact design allows for efficient storage, while its rugged frame withstands the rigors of daily ground handling operations. These features make it ideal for both indoor and outdoor use across maintenance environments.

Unlike diesel-powered GPUs, the UDC-420M operates electrically, producing zero emissions and minimal noise, making it ideal for hangar operations. Electric rectifiers like this one reduce fire risks associated with fuel vapors and meet FAA safety guidelines for confined-space maintenance. The clean operation also contributes to a safer and more comfortable working environment for technicians.

The Unitron UDC-420M requires minimal maintenance due to its solid-state design, which features no moving parts. Routine inspections typically involve checking electrical connections, cable integrity, and filter cleanliness to ensure optimal system performance. The manufacturer recommends scheduled testing of protective circuits to ensure continued safety compliance and consistent power output throughout the unit's life.

A 28V DC rectifier, such as the UDC-420M, offers quiet, emission-free power suitable for hangar and ramp operations, unlike gas or diesel-powered generators that emit fumes and noise. It also provides clean, regulated power, ensuring that aircraft electronics are protected from surges and harmonic distortion. Over time, electric GPUs lower operating costs through reduced fuel consumption and less frequent maintenance.

Yes. The rectifier is equipped with an automatic cooling system that activates as the internal temperature increases, maintaining optimal performance during extended use. The system’s thermal protection prevents overheating and ensures a consistent output voltage, even under heavy load conditions, making it reliable for long-duration aircraft maintenance tasks.

The rectifier features automatic voltage regulation and input compensation, ensuring a stable DC output even in the presence of fluctuations in the AC power supply. Its advanced filtering circuits eliminate ripple voltage that could interfere with sensitive avionics or flight control systems. This ensures a steady and noise-free power source for precise ground diagnostics.

The UDC-420M supports optional accessories, including output cables, connectors, and protective covers for added operational flexibility. Units can also be equipped with digital metering displays, remote control panels, and cable storage racks for enhanced usability and organization. These accessories facilitate the integration of the rectifier into multi-aircraft or multi-bay maintenance setups.

Unitron provides a standard two-year limited warranty on the UDC-420M, covering defects in materials and workmanship. In addition to an extensive inventory of spare parts for the UDC-420M, PJi also offers preventative maintenance services and repairs to ensure the GPU operates within factory specifications.