The Generator Line Contactor (GLC) plays a critical role in the electrical systems of modern aircraft. Understanding what is Generator Line Contactor in aviation is essential for anyone involved in aeronautical engineering, maintenance, or piloting. It serves as the bridge between the aircraft’s generators and the electrical distribution system, ensuring stable power delivery and protecting electrical components from faults.
What is Generator Line Contactor in Aviation?
The Generator Line Contactor, commonly abbreviated as GLC, is an electrical relay or switch used to connect or disconnect an aircraft’s generator from the main electrical bus. It functions as an automatic connection point controlled by the Aircraft Electrical Power Control System (EPCS). The GLC confirms that the generator operates within acceptable voltage and frequency limits before allowing it to feed power into the system.
In aviation systems, voltage regulation typically stays in the range of 115/200 volts AC (three-phase) at a frequency of 400 Hz, with some aircraft also using 28 volts DC buses. The GLC monitors these parameters and will close if conditions meet criteria such as voltage within ±5% of nominal and frequency stability within ±2 Hz. If conditions fall outside these limits, the GLC opens and isolates the generator, preventing damage to electrical systems or unsafe power conditions.
Role of Generator Line Contactor in Aircraft Electrical Systems
The Generator Line Contactor plays an essential role in maintaining reliable power distribution onboard aircraft. By controlling when the generator output is linked to the aircraft’s load buses, the GLC helps protect against power surges, electrical faults, and prevents out-of-sync power sources from damaging components.
When an engine-driven generator reaches rated speed and voltage output, the GLC closes, allowing the generator to supply electricity to the main bus. In the event of generator failure, abnormal voltage, or a fault detected by circuit protection systems, the GLC opens to isolate the problematic generator. This automatic disconnection minimizes the risk of system-wide electrical failure and enhances flight safety.
Technical Specifications and Operation of Generator Line Contactor
Generator Line Contactors are designed to withstand high electrical loads and rapid switching. They are built using electromagnetic coils and contact points that open and close under the command of the aircraft’s electrical control unit (ECU). Typical GLCs operate at current ratings up to 1000 Amps and voltages up to 270 volts AC or 28 volts DC, depending on system design.
The timing for the GLC’s operation is critical. Closing and opening times usually range from 10 to 30 milliseconds, ensuring the generator is only connected under safe conditions. These rapid switching capabilities prevent transient voltage spikes and maintain system stability. The design also incorporates arc suppression mechanisms since the contactor must interrupt high current flow without damage or excessive wear.
Modern GLCs integrate with the aircraft’s electrical monitoring sensors, enabling real-time feedback to the flight deck and maintenance systems. Aircraft such as the Boeing 737 and Airbus A320 use GLCs as part of their Integrated Drive Generators (IDGs) electrical control schemes, regulated by complex electronic controllers that manage load sharing between multiple power sources.
For a detailed exploration of aircraft generators and associated components, refer to the FAA’s handbook on [Aircraft Electrical Systems](https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/).