SGS-40PU

SGS-40PU aircraft AC generator

The SGS-40PU is a three-phase synchronous AC generator used in aircraft electrical power systems. It supplies onboard AC consumers and works as one of the main electrical power sources on helicopters such as Mi-8MTV and Mi-17, where this generator type is installed according to the aircraft configuration. The unit is driven from the engine accessory gearbox and produces three-phase alternating current for the aircraft network. It does not work alone: voltage regulation, switching, protection, and load distribution are handled by related electrical equipment installed on the aircraft.

SGS-40PU as the main onboard power source

In operation, the generator converts mechanical rotation from the engine drive into electrical power. On helicopters with TV3-117 family engines, the generator is installed on the engine drive gearbox and runs within the specified rotor speed range. Its output feeds the aircraft AC system, which then supplies connected onboard equipment directly or through conversion and distribution units. If the generator output is unstable, the fault is not always inside the generator itself. Drive speed, voltage regulation, wiring, protection relays, bus condition, and load level also need to be checked.

Electrical system around generator SGS-40PU

The SGS-40PU works together with voltage regulation equipment, generator protection circuits, switching devices, aircraft AC buses, feeder lines, and cockpit indication. In a complete power supply system, the generator output must be controlled and protected before it is connected to the onboard network. The associated equipment monitors voltage, current, phase condition, and operating mode depending on the aircraft scheme. During maintenance, the generator is usually checked as part of the whole electrical chain, not as an isolated rotating machine.

Cooling and service points for SGS-40PU

The generator uses forced air cooling by airflow through the unit. Cooling condition matters because the generator works under load and produces heat during normal operation. Blocked airflow, worn brushes, poor contact, bearing condition, or drive-related issues can affect operation. The generator uses electrocarbon brushes, including the 555.126 brush type specified for this equipment. For service work, technicians normally check brush wear, collector condition, fastening, electrical connections, external damage, and signs of overheating.

Identification and ordering checks for SGS-40PU

Before ordering, the marking on the installed generator should be checked against the aircraft parts catalog, engine drive equipment list, or maintenance documentation. Helicopters of the same family may have different electrical configurations after overhaul or modification, so the aircraft type alone is not enough for final selection. A request should include the generator designation, helicopter type, engine or gearbox installation reference, required condition, and documentation requirements. The product is also known under alternative designation СГС-40ПУ.

Product Type: Three-phase synchronous aircraft AC generator
Function: Generation of onboard three-phase AC electrical power
Application / Where Used: Aircraft electrical power supply systems
System / Installation Area: Engine accessory gearbox / onboard AC power system
Compatible Aircraft / Equipment: Mi-8MTV, Mi-17 and applicable helicopter configurations with TV3-117 family engines
Rated Power: 40 kVA
Rated Voltage: 208 V line voltage
Rated Load Current: 111 A
Current Type: Three-phase AC
Frequency Range: 387.5 to 417.5 Hz
Nominal Frequency: Approx. 400 Hz
Rotor Speed: 7750 to 8350 rpm
Number of Phases: 3
Cooling: Forced airflow cooling
Drive: Engine accessory gearbox, including TV3-117-type installations
Brush Type: Electrocarbon brush 555.126
Weight: Not more than 41 kg
Technical Documentation: Aircraft electrical system documentation / generator technical documentation

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Warranty
All products are covered by a standard 6-month warranty.
Extended warranty is available upon request and is agreed individually; it may affect the final product price.