Electric power start up of aviation engines

Лабораторная работа

Астрономия и авиация

Electric power strt up of vition engines The purpose of work is fmiliriztion with the equipment intended for ircrft onbord power circuit supply for engine strt up nd power delivery of onbord consumers. Brief theoreticl dt To supply the prticulr electric power proper to the ircrft onbord power circuit when the min engines nd uxiliry power unit re not running specil selfpropelled or towed Ground Power Units re pplied for tht purposes. It lso llows performing n electricl power strt up of min ircrft jet engines by spinning the high...



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Laboratory work 1.6.

Electric power start up of aviation engines

The purpose of work is familiarization with the equipment intended for aircraft on-board power circuit supply for engine start up and power delivery of on-board consumers.

Brief theoretical data

To supply the particular electric power proper to the aircraft on-board power circuit when the main engines and auxiliary power unit are not running, special (self-propelled or towed) Ground Power Units are applied for that purposes. It also allows performing an electrical power start up of main aircraft jet engines by spinning the high pressure stage shaft using the power starter, installed on the power take-of gear box. It saves the fuel consumed by main jet engines and auxiliary power unit and power charge of on-board aircraft batteries. Ground Power Units are also applicable for on-ground aircraft power supply during in-line and periodic maintenance procedures and proper system operation of the systems and devices.

1.1. Power Standards, which is to be supplied into aircraft onboard system.

Power Standard, socket pins layout and protection system of any ground power unit should comply with the latest edition of ISO 6858 Aircraft – Ground Support Electrical Suppliers – General Requirements.

The a.c. power System shall be three-Phase, four-wire, starconnected having a nominal voltage of 115/200 V, a nominal frequency of 400 Hz and a Phase sequence A-B-C. The neutral Point shall be connected in accordance with the circuits shown in fig 1.6.1.

A.C. steady state output characteristics must be the following:

The individual and average of the three-Phase voltages at the connector shall be within the range 112 to 118 V for all loads including the permitted Unbalance, up to rated load at power factors between 0,8 lagging and l,0. The frequency of the supply shall be maintained within the limits 390 Hz and 410 Hz.

Fig. 1.6.1. Standard wiring diagram for three-Phase a.c. plug and socket

The d.c. power System shall be a two wire System having a nominal voltage of 28 V, the output of which should be connected in accordance with the circuits shown in fig. 1.6.2.

D.C. steady state output characteristics must be the following:

The voltage at the connector shall be within the range 26 to 29 V at any load condition up to rated load. When the facility is used for engine starting, the voltage at the connector shall not be less than 20 V. The maximum current rating for this condition shall be declared.

Fig. 1.6.2. Standard wiring diagram for d.c. plug and socket

The minimum protection to be provided shall meet all safety requirements. Means shall be provided for periodic checking of these minimum protection circuits. When a protective circuit has operated the facility shall remain disconnected from the aircraft until manually reset.

1.2. GPU-4000 Unit Description

Ground Power Unit made by TLD manufacturer can be made in two versions: self-propelled and trailer-mounted (fig. 1.6.3. and fig. 1.6.4.)

Fig. 1.6.3. Self-propelled Ground Power Unit mounted on the chassis of GMC W3500 truck

Fig. 1.6.4. Trailer mounted Ground Power Unit

Special equipment of the Ground Power Unit consists of the diesel engine driven generator placed in enclosure, diesel engine supply systems, control panel, relay panel, connecting cables stowage compartment.

Diesel engine driven generator assembly is shown in fig. 1.6.5.

Fig. 1.6.5. Diesel engine driven generator assembly: 1 - Air filter; 2 - Exhaust silencer; 3 - Instrument panel; 4 – Engine; 5 - Fuel Tank; 6 – Generator; 7 – Radiator; 8 - Charge air cooler;

9 - Electrical Box.

2.1. GPU-4000 Unit Operation

The GPU-4000 SERIES is a self contained, diesel engine driven, ground power unit. The unit is designed to supply regulated 400 Hz electrical power to a parked aircraft for operation of the aircraft's electrical equipment when the on-board generators are not running. The components of the GPU-4000 SERIES are of a simple but rugged design with sufficient safety devices to ensure a long, trouble free service life. The illuminated control panel provides easy night operation.

Ground Power Unit (GPU) operation features

A GPU is generally a non-motorised unit with the express purpose of delivering electrical power

to a parked aircraft, allowing the aircraft’s equipment to run when its APU (Auxiliary Power Unit) is shut down or nonexistent. The basic unit is designed to be mounted on the back of a truck, a four-wheel trailer or in the vicinity of an aircraft loading bridge.

NEVER disconnect the GPU unless given authorisation by the captain.

ALWAYS allow the engine to idle for the required time after use

(see manufacturers recommendations)

ALWAYS ensure that the power cable has been properly disconnected and stowed prior to attempting to move the unit.

NEVER use the Emergency Shut down device unless there is a real and immediate emergency. Doing so may damage this equipment. This device is not to be used to do normal shut down.

Unit Operation

This section contains information and instructions for the safe and efficient operation of the unit.

1. Ensure the fuel tank contains sufficient fuel.

A full tank will give approximately six hours running. (Full load continuous)

2.2. Engine Starting Procedure

The engine and generator operating controls and monitoring equipment are mounted on the instrument panel.

1. Turn the ignition switch to the "START" position.

2. Release the ignition switch when its starts.

3. The engines start at idle speed. Let the engine warm up to the operating temperature.

4. Hold up the engine switch in the momentarily position to bring the engine to operating speed to build up generator voltage.

2.3. Positioning the GPU

1. If required, turn the Light ON/Off switch to ON to switch on the hazard light and the panel lights.

2. Manoeuvre the GPU into position adjacent to the aircraft ground power socket and apply the parking brake by latching the drawbar in the upright position.



2.4. Deliver Power to the Aircraft

1. Connect the power to the AC external power receptacle on the aircraft.

(Get advice from the Ground Engineer or Flight Coordinator).

2. Hold the contactor switch (#1 or #2) in the "CLOSE" position.

3. When the output lamp (#1 or #2) lights, release the contactor switch.

2.5. Removing Power from the Aircraft

(Get advice from the Ground Engineer or Flight Coordinator).

1. Place the contactor switch in the "OFF" position.

2. Disconnect the power cable from the aircraft. (Get advice from the Ground Engineer or Flight Coordinator).

3. Stow the power cable on the generator in the proper location.

2.6. Shutting Down the Engine

1. Turn the ignition switch to "OFF" position. The engine will ramp down to idle and remain in idle for approximately one (1) minute to cool down. It will then shut down automatically.



1. Idle/Rated Speed Switch 2. #1 Output Contactor Switch 3. #2 Output Contactor Switch 4. 28.5 VDC Contactor Switch 5. Ignition Switch 6. Emergency Stop Switch 7. #1 Output Indication Light  8. #2 Output Indication Light 9. 28.5VDC Output Indication Light 10. Engine Cool Down Light 11. Engine Fault Light 12. Engine Maintenance Light 13. Intake Heater Light 14. Generator Control Module Scroll Up 15. Generator Control Module Scroll Down 16. Generator Control Module Scroll Left Button 17. Generator Control Module Scroll Right Button 18. Engine Diagnostic Switch 19. Engine Diagnostic Connector 20. Fuel Level Gauge 21 & 22. Panel light.



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