Back to case studiesBackground: Aircraft Ground Power Units
The aircraft ground power unit has an optimized 1,846 RPM brushless revolving field generator, which efficiently produces 90 kVA (72 kW) 400 Hz AC power to start and service aircraft.
The diesel generator provides critical operational and diagnostic information to aircraft operators and maintenance personnel.
Digital Generator Control Module (GCM)
The digital generator control module (GCM) features voltage regulation, generator fault protection, and a generator operating parameter display. The GCM monitors the 400 Hz output when 400 Hz is in use and automatically switches over to monitor 28.5 VDC output when the optional 28.5 VDC transformer rectifier is in use.
The voltage regulator provides line drop compensation on 400 Hz as well as line drop compensation and current limiting on the optional 28.5 VDC transformer rectifier. The GCM displays the generator output operating parameters such as voltage, current, and frequency digitally on a backlit LCD.
The Digital Generator Control Module (GCM) is responsible for:
• Voltage regulation
• Generator fault protection
• Displaying key operational parameters like voltage, current, and frequency on a backlit LCD screen.
Engine Control Module (ECM)
The engine control module (ECM) uses electronic engine governors to provide precise frequency regulation and fast transient response. Engine protection features for low oil pressure and high coolant temperature are programmed into the ECM. An engine diagnostic connector is provided for communicating with the engine.
The control module displays important operating parameters, such as engine speed, voltage and hours, oil pressure, coolant temperature, and the automatic cool-down cycle.
The combination of the GCM and ECM provides a comprehensive and unique solution for the control and management of the aircraft diesel generator, ensuring both stable power output and engine protection.
Application Requirements
All aircraft service equipment must be designed with sophisticated EMI shielding. No RF transmission can escape the unit to interfere with aircraft communication systems.
As a result, the aircraft ground power unit is built with extra-thick panel walls to offer excellent EMI shielding and protection, including all around the control panel.
The rugged diesel power generator control panel must handle extended daily use in challenging operating conditions, including varying weather conditions, wide temperature ranges, humidity, shock, vibration, and more. The reliable interface must also meet brightness requirements for daytime visibility.
Solution: CNX714 LED Panel Mount Indicator
Due to its robust and reliable design, the CNX714 LED panel mount indicator was selected for use in the aircraft diesel generator control panel.
To meet EMI shielding requirements, the CNX714 panel mount indicator was modified with an extra resistor on the PCB.
The CNX714 Series eases assembly via fast pitch threads that require only one turn.
Featuring FlexVolt technology, the LED indicator can be used with voltages ranging from 5V to 28V DC.
A wide 180-degree viewing angle delivers high visibility, particularly in daylight applications. And with an IP67 rating, the moisture-sealed LED indicator is rugged enough for the harsh outdoor conditions found at airports around the world.
CNX714FV Specifications
The RoHS- and REACH-compliant indicator has a mounting hole size of 14mm (0.551”) and 24 AWG wire leads. The LED indicator is available in red, yellow, green, blue, and white.
The series provides illumination for applications that require consistent identification and communication through light, and achieves full brightness in microseconds.
Results & Benefits
The CNX714 Series LED panel mount indicator delivers clear and reliable communication to the user via light to ensure safe and proper operation of the aircraft ground power unit.
The modified indicator ensures the control interface is free of RF interference. The LED indicator also simplifies installation and maintenance with its one-turn threaded mounting and long operating life.
Value-Added Services
VCC understands the importance of visual communication and becomes an extension of your design team, providing technical advice for your design challenge.
Contact VCC’s design engineers to discuss rugged panel mount indicators for your ground support equipment.
Case Study Media
Frequently Asked Questions About LED Indicators for Aircraft Ground Power Units
What Does an Aircraft Ground Power Unit Do?
An aircraft ground power unit supplies electrical power to start and service aircraft on the ground. The unit in this case study uses a 1,846 RPM brushless revolving field generator that produces 90 kVA (72 kW) of 400 Hz AC power.
Why Do Aircraft Ground Power Units Need EMI Shielding?
No RF transmission can escape the unit and interfere with aircraft communication systems. This ground power unit uses extra-thick panel walls for EMI shielding, including around the control panel, and VCC modified the CNX714 indicator with an extra resistor on the PCB to meet the shielding requirements.
What Is FlexVolt Technology?
FlexVolt technology lets the CNX714 LED panel mount indicator operate on voltages from 5V to 28V DC.
How Is the CNX714 LED Panel Mount Indicator Installed?
The CNX714 fits a 14mm (0.551”) mounting hole and connects with 24 AWG wire leads. Its fast pitch threads require only one turn, which eases assembly.
