Refrigeration Compressor Starting Unloader

At a star-delta start of electric motors it is often considered necessary to limit the compression work of the machine at the starting moment in order to reduce the starting torque of the electric motor.
Usually, a solenoid valve is used in a by-pass arrangement which in the starting up phase short circuits the discharge side to the suction side of the compressor.
At the same time, a non-return valve must be fitted in the discharge line to the condenser preventing the return flow of discharge gas to the compressor.
When the electric motor has reached its max. number of revolutions per minute, a switch takes place from star to delta start.
The solenoid valve is closed and the compressor now works under normal conditions.

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Main engine interlocks

Interlocks are provided so that the engine can be started or reversed only when certain conditions have been fulfilled. When there is a remote control of engines, it is essential to have interlocks. This reduces the possibility of engine damage and any hazards to the operating personnel. Turning gear Interlock . This device prevents the engine from being started if the Turning gear is engaged. Running Direction Interlock . This prevents the fuel from being supplied if the running direction of the engine does not match the Telegraph. Starting Air Distributor in end position . This prevents starting from taking place if the shifting of the Distributor has not been completed. Main Lube. oil pressure, Piston cooling pressure, Jacket water pressure, and important parameters must be above the required minimum. Auxiliary Blower Interlock . The Auxiliary Blower is provided in case of Constant pressure turbo charging. Air Spring pressure Interlock . In case of the present generation...

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Shell Expansion Plan

It is a two dimensional drawing of a three dimensional surface of the ship’s hull form. This plan is very useful for the following information:It is used for marking the location of a hull Damage on this plan by identifying the strake number , letter and frame number so that the exact location of the damage and also suggested repairs are marked in a localised copy. The shell expansion can be used for finding areas of painting surfaces such as topside, boot topping and bottom areas by applying Simpsons rules directly. In the shell expansion the vertical scale used is different from the horizontal scale and a suitable adjustment has to be made when calculating areas. This becomes useful in solving disputes concerning areas of preparation and painting. It gives information on the thickness of the original strake which is indicated by the number in the circle shown in the strake. The quality of steel used is also shown by letters A,B,D E and AH, BH,DH, EH.

MEOclassIIexamnotes

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