UNIT 9 ELECTRONIC LOAD CONTROL UNITS
(ELCUS)/SMART CONTACTORS
AIMS OF THE UNIT:- to understand electronic load control units (elcus)/smart contactors
TASKS 1 Do your best to answer the brainstorming question. 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 Make up exercises as in the UNIT 2 (Master`s degree students individual work with the teacher) page 210 (exercises for better remembering the topic). 7 Speak on the topic. Given schemes will help you to remember and understand the topic. 8 Find more information about the topic and make up a project work on the topic.
Higher power aircraft loads are increasingly switched from the primary aircraft busbars by using Electronic Load Control Units (ELCUs) or ‘smart contactors’ for load protection. Like contactors these are used where normal rated currents are greater than 20 A per phase, i.e. for loads of around 7 kVA or greater. The ELCU has in-built current sensing coils that enable the current of all three phases to be measured. Associated electronics allow the device trip characteristics to be more closely matched to those of the load. Typical protection characteristics embodied within the electronics are I2t, modified I2t and differential current protection.
UNIT 10 EXTERNAL/GROUND POWER
AIMS OF THE UNIT:- to understand external/ground power
TASKS 1 Do your best to answer the brainstorming question. 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 Make up exercises as in the UNIT 2 (Master`s degree students individual work with the teacher) page 210 (exercises for better remembering the topic). 7 Speak on the topic. Given schemes will help you to remember and understand the topic. 8 Find more information about the topic and make up a project work on the topic.
The aircraft battery provides an autonomous means of starting the engine. Certain types of operation, e.g. cold weather and repeated starts, could lead to excessive demands, resulting in a battery that is not fully charged. An external power supply system schematic provides power to the aircraft, even when the battery is flat, or not installed. External power can be from a ground power unit or simply from a battery pack.On larger aircraft installations, a connector with three sockets supplies external power. These sockets connect with three pins on the aircraft fuselage.Different-size pins are used on the connectors to prevent a reverse polarity voltage being applied. Some aircraft installations have a ground power relay. Power can only be supplied into the aircraft via the main pins when the third (shorter) pin makes contact. The third pin is used to energize the ground power relay; this additional relay prevents arcing on the power connector as illustrated in Fig. 8.9. External AC power is applied in a similar way, except that the three phases have to be connected via individual circuits.
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