TR-115/36

TR-115/36 step-down transformer in aircraft electrical systems

The TR-115/36 is a compact aircraft step-down transformer designed to convert single-phase AC power from 115 V to 36 V. It is used in onboard electrical systems of airplanes and helicopters where low-voltage AC power is required for instruments, indication circuits and selected radio-electronic equipment. The transformer operates from the standard aircraft 400 Hz AC network and provides a stable 36 V output for connected consumers.

Power supply function of the TR-115/36

The main function of the TR-115/36 is to supply aircraft equipment that cannot be powered directly from the 115 V AC network. It steps the voltage down to 36 V and feeds low-power onboard consumers. One of the typical applications is power supply for remote inductive pressure gauges, including DIM-type instruments. Correct transformer operation is important because unstable or missing 36 V power can affect the indication of pressure-related systems in the cockpit.

TR-115/36 for DIM pressure indicators

The TR-115/36 is commonly associated with remote inductive pressure measurement systems. In such circuits, the transformer provides the required 36 V AC supply for the pressure indicator equipment. These systems may monitor fuel, oil, hydraulic or pneumatic pressure depending on the aircraft layout. Since pressure indication is important for crew awareness, the transformer is often treated as a small but essential part of the aircraft instrument power supply chain.

Main and reserve transformer installation

On many aircraft, transformers of this type may be installed in pairs: one main and one reserve unit. The crew can switch between them manually using a cockpit switch, depending on the aircraft electrical scheme. This arrangement improves reliability of the instrument power supply. If the main transformer or its circuit fails, the reserve transformer can be selected to restore 36 V power to the connected equipment. Exact switching logic must be checked by the aircraft wiring diagram.

Compact construction of the TR-115/36

The TR-115/36 belongs to the compact TR-series single-phase aircraft transformers. The unit is built in a small housing suitable for installation in limited equipment spaces. Its magnetic core is made from thin electrical steel laminations designed for operation at 400 Hz. The higher aircraft network frequency allows a smaller transformer size compared with standard industrial 50 Hz transformers. Depending on execution, the unit may be supplied in a protected, sealed or open-style aviation housing.

TR-115/36 operation in aircraft conditions

The transformer is designed for continuous operation in aircraft environments with vibration, temperature variation and long service life requirements. It is suitable for use in helicopters such as Mi-8, Mi-26 and Mi-171E, and in aircraft such as An-24, depending on configuration. Before replacement, the exact installation point, connection scheme, mounting version and aircraft documentation should be checked. Even if the electrical rating is the same, mounting and wiring details may differ between aircraft types.

Supply and inspection of TR-115/36

For procurement or replacement, the transformer should be specified by its full designation TR-115/36 / ТР-115/36. Before installation, the unit should be checked for winding continuity, insulation resistance, output voltage, overheating marks, terminal condition, housing condition and mounting integrity. For aviation use, passport, quality documents, acceptance marks or repair / test documents should be confirmed where required.

Product Type: Aircraft step-down transformer
Designation: TR-115/36
Alternative Designation: ТР-115/36
Function: Conversion of 115 V AC to 36 V AC for aircraft equipment
Application / Where Used: Aircraft electrical and instrument power supply systems
System / Installation Area: Instrument power circuits, pressure indication systems and selected onboard radio-electronic equipment
Typical Consumers: Remote inductive pressure gauges, including DIM-type instruments, and compatible low-voltage AC equipment
Input Voltage: 115 V AC
Output Voltage: 36 V AC
Nominal Frequency: 400 Hz
Number of Phases: Single-phase
Current Type: Alternating current
Rated Power: Approx. 20–30 W depending on series / execution
No-Load Current: Not more than 0.05 A
Operating Mode: Continuous
Service Life: Not less than 10,000 hours
Magnetic Core: Laminated electrical steel core optimized for 400 Hz operation
Construction: Compact aircraft transformer, sealed or open housing depending on execution
Mounting: Fixed mounting through holes in the base / clamp for M3 screws
Maximum Dimensions: Not more than 40 × 72 × 65 mm depending on execution
Typical Compact Body Reference: Approx. 43 × 36 × 33.5 mm without terminals and mounting lugs
Weight: Approx. 0.35–0.49 kg depending on execution and protective housing
Operating Temperature Range: −60 to +60 °C
Operating Features: Increased vibration resistance for aircraft use
Compatible Aircraft / Equipment: Mi-8, Mi-26, Mi-171E, An-24 and other aircraft / helicopters depending on electrical-system configuration
Typical Installation Logic: Main and reserve transformer installation with manual cockpit switching depending on aircraft scheme
Inspection / Testing: Winding continuity check, insulation resistance check, output voltage check, no-load current check, terminal and housing inspection
Technical Documentation: Product passport, aircraft electrical system documentation and quality / test documents as applicable

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