Free Piston Engine

The Free Piston Engine is a combination of reciprocating engine and rotary turbine. It is called free piston engine because the freedom motion for Mechanical linkage which gives variable stroke according to load.

ADVANTAGES

1. Mechanical simplicity

2. Less power to weight ratio

3. Lower turbine operating tempeatures

4. Multi fuel capability

5. Flexibility and reliability

6. Easy starting and control

LIMITATIONS

1. Poor fuel economic

2. Less stability

3. Poor part load efficiency

4. High combustine rates

5. Reduction gearing

APPLICATIONS

1. Free piston engines are widely used as submarine air compressor units

2. These engines are suitable for power generation in medium power range

3. Free piston engine have been tride in ship propulsion, road and rail traction and even in aircrafts.

4. It is used in mixed gas steam cycle.

         keep reading.......   

QUESTIONS ON MARINE ELECTRICAL PART....(with answers)-PART I

1. What is the only indication of a fully charged alkaline cell?              Ans :1.6-1.8v
2. How is salt contamination of motor removed?                                Ans : wash fresh water & dry
3. Electrical insulation will break down more quickly due to?                Ans : high temperature & vibration
4. What can excessive application of petroleum jelly cause?               Ans: burning & pitting of constriction 
5. What is used to adjust power factor?                                                 Ans:  The excitation of alternator used to adjust
6. Which of the listed section of an emergency switch bus is used to supply power to alarm signal under emergency situation?              Ans: 24v dc busbar
7. Equal power factor on parallel AC generator are maintain by an automotive?                                                                                Ans : voltage regulator
8. Can you normally the shore supply with the ship alternator?            Ans: its not possible.
9. What is minimum allowable temperature of electronic during the charging of lead acid battery?                                                             Ans:  45⁰c
10. If transformer is connected to dc source the transformer     will overload at the ……………….                                                                              Ans: primary coil
11. What should be used to dress the copper contacts?                       Ans: a fine file or glass paper.
12.  What         is    the    main        function             in the                use of a capacitor is starting a single phase motor?                                                                                  Ans: split the phase to establish a rotating magnetic field.
13. What is usual short circuit time delay for the alternator over current production?                                                                                 Ans: 0.1 to 3 seconds
14. What a star- delta star when is the change over operated?            Ans: at fully rater speed
15. A purpose of suppressor?                                                              Ans: to reduce electrical inter France.
16. The force that causes free electronics to flow in conductor as an electric current flow is called?                                                          Ans: electromotive force.
17. What mist is    guarded      against where clearing     alternator winding with low pressure air?                                                                        Ans: 1.dirt is not pushed. 2. deeper into winding.
18. A circuit with a blown fuse can be described as?                            Ans: open circuit.
19. What is the starting torque? When the motor winding are in star as percentage of fully load torque?                                                     Ans: 80%
20. What is air pressure to be used when blowing out motors?              Ans: 1.75 bar                                                    Keep reading the blog for the futher questions on different parts of marine engineering.....happy reading..(the answers are given may be approx. please refer someother sources also.)