Aircraft Electrical Power Generation and Distribution - Coursework Example

This magnetism in turn induces voltage into an armature which then carries electrical power to generator control unit (GCU). This power is rectified and conducted to exciter field winding. This then induces voltage into exciter output winding field. This output is rectified to DC and flows through the output field winding and it’s induced into the main output coils. A voltage regulator is incorporated to control the voltage generated by the system depending on the load and the engine speed.

It consists of a Generator Control Unit that ensures that all the 3 phases produce equal voltages or the difference is within limits. It also has provision to ensure that the frequency is maintained within the desired limits. Over voltage (OV) - When the voltage at the point of reference (POR). Is above 125V, there is a faculty voltage regulator, and the generator control relay (GCR) is de-energized. Q2. Explain with an aid of a diagram how an integrated drive generator (IDE) works. The IDE has 2 main parts. i. A drive. ii. A brushless AC generator.

The drive part makes sure that the generator operates at a fixed rpm, regardless of the engine rpm and generator load. The IDG input shaft drives the generator through a reduction gearing and a differential gear. When the generator operates at 12000 rpm the generator frequency is 400 Hz. When the input shaft increases or decreases the frequency of the generator increases or decreases too. This deviation from 400 Hz is detected in the GCU which supplies an electrical signal to a servo valve in the IDG drive part.

This servo valve in turn controls through a control cylinder a hydraulic unit which starts to operate in an anti/clockwise direction. Since the hydraulic unit is connected to another input of the differential gear, the generator rpm increase or decrease is less than the rpm fluctuation on the input shaft. As a result, the generator frequency stays approximately constant. The hydraulic unit operates on 240 up to 280 psi. This charge pressure is made by a charge pump and charge relief valve; the charge oil is also used to cool the generator.

The oil flow is between 34 and 53 liters. Drain oil from the generator and sump is supplied through a scavenge filter to an external oil cooler by three pumps , which are driven by the accessory drive gear on the differential gear These pumps are generator scavenge pump, sump scavenge and inversion scavenge pump. The accessory drive gear also drives the de-aerator and charge pump. The return oil from the cooler passes the de-aerator and it goes back to the charge pump. Q3. Explain how a transformer rectifier (TRU) works.

The TRU as the name suggests is both a transformer and a rectifier. The transformer steps down 12000 V to 28 V while the rectifier converts the 400Hz AC power to DC. The 3 phase AC is routed to the primary side of the transformer and is in connected in star order. Two secondary sides are at the transformer. SEC 1 is in star order while SEC 2 is in delta order. The output of the secondary side is rectified by full wave rectifier circuits. The purpose of the two different secondary sides with separate rectification is to have less ripple of the rectified 28V DC power output.

If the temperature of the rectifiers is over a certain limit, overheat switches providing signals to the monitor circuit in the TRU causes the TRU