VII Using the figures describevariable frequency (VF) power generation.
Variable frequency power generation VSCF power generation UNIT 3 EMERGENCY POWER GENERATION
AIM OF THE UNIT:- to identifyemergency power generation
TASKS 1 Do your best to answer the brainstorming questions. 2 Read the text for general understanding. 3 Make up questions to the text. 4 Find the sentences with the new words in the text. Give the Kazakh or Russian equivalents of the words. 5 Write sentences with the new vocabulary. 6 Do the given exercisesfor better remembering the topic. 7 Speak on the topic. Given schemes will help you to remember and understand the topic. 8 Make up a project work on the topic.
1 How many main standard methods of providing back-up power are there on civil transport aircraft? 2 What is RAT? In certain emergency conditions the typical aircraft power generation systemmay not meet all the airworthiness authority requirements and additional sources of power generation may need to be used to power the aircraft systems. The aircraft battery offers a short-term power storage capability, typically up to 30 minutes. However for longer periods of operation the battery is insufficient. The operation of twin-engined passenger aircraft on ETOPS flights now means that the aircraft has to be able to operate on one engine while up to 180 minutes from an alternative or diversion airfield. This has led to modification of some of the primary aircraft systems, including the electrical system, to ensure that sufficient integrity remains to accomplish the 180 minute diversion while still operating with acceptable safety margins. The three standard methods of providing back-up power on civil transport aircraft are: 1 Ram Air Turbine (RAT); 2 Back-up Converters; 3 Permanent Magnet Generators (PMGs) The Ram Air Turbine or RAT is deployed when most of the conventional power generation system has failed or is unavailable for some reason. The RAT is an air driven turbine, normally stowed in the aircraft ventral or nose section that is extended either automatically or manually when the emergency commences. The passage of air over the turbine is used to power a small emergency generator of limited capacity, usually enough to power the crew’s essential flight instruments and a few other critical services. Typical RAT generator sizing may vary from 5 to 15 kVA depending upon the aircraft. The RAT also powers a small hydraulic power generator for similar hydraulic system emergency power provision. Once deployed then the RAT remains extended for the duration of the flight and cannot be restored withoutmaintenance action on the ground. The RAT is intended to furnish the crew with sufficient power to fly the aircraft while attempting to restore the primary generators or carry out a diversion to the nearest airfield. It is not intended to provide significant amounts of power for a lengthy period of operation. EXERCISES FOR BETTER REMEMBERING THE TOPIC
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