SYNTHESE ANGLAIS

Question 1

Electrical Engineering How to produce electricity Onboard

Answer 1

• Diesel engine coupled to an alternator = Genset
  (to produce electricity and share the load)
• When underway the shaft generator produce the electricity
• When stoping a genset, the load must be shifted to another
• If too much load => automatic switch off of non essential devices (load shedding)

Question 2

Transformer

Answer 2

Adjust the voltage

Question 3

Main SwitchBoard

Answer 3

Fitted with :

• Circuit breakers
• Fuses
• Dials for safe power supply to the power grid

Question 4

Circuit Breaker

Answer 4

Protect equipment from overcurrent or voltage surge

Question 5

Differential Circuit breaker

Answer 5

Protect equipment agains insulation default (driven by a time lag delay)

Question 6

Cables

Answer 6

Energy in the power grid is carried in the power grid through copper wires wrapped into insulation sheath

Question 7

Alternating Current

Answer 7

• Easier to produce and transform

- If need to produce DC current, we can use rectifier

Question 8

2 main types of electric propulsion system

Answer 8

• DC prop system : Rectifier + Power conditionner ti convert AC in DC
• AC prop system : Very advantageous
• High flexibility
• Economic (efficient fuel consumption)
• Large amont of special purpose power
• Less machinery => better space using

Question 9

EDG

Answer 9

• Heated by an Electrical heater
• Started by an electrical motor (batteries), with air or emergency hydraulic starting system
• Run with MGO with it’s dedicated tank
• Lub thanks to engine driven pump pressurises with lube oil
• Driven fan is used to cool the cooling water stored in its own header tank
• Electricity Provided by the alternator (heated by it’s own heater) to bus bar protected by a bus-tie breaker
• Regulation : Weekly starting and Monthly Loading

Question 10

Star-delta Starting

Answer 10

1) Windings are connected in star mode to reach 80% of rated speed
2) Rotor windings switch to delta connection

it divide the starting current and torque by 3

Question 11

3 types of Electric Motor

Answer 11

• Compound
• Induction
• Synchronous

Question 12

Compound Motor

Answer 12

Series + shunt technologie => High starting torque / Constant Speed

Question 13

Induction Motor

Answer 13

Widely used Onboard

• No Brushes
• Strong Starting Current
• Low Torque

Question 14

Synchronous Motor

Answer 14

3 phases alt current through coils => magnetic field

Brushes convey current to the rotor => start to rotate

Question 15

PEM

Answer 15

• 2 stator windings supplied separately via transformers and frequency converter
• EMCY : Can be used as half motor => reduced power output