MAIN ENGINE ROTATIONAL SPEED DETECTOR

PURPOSE:To detect with low cost and simplicity and without using a separate detector changing rotatinal speed of a main engine of a ship, etc. by obtaining frequency signal from the output of the electric power generator driven by the main engine in a main engine rotational speed detector. CONSTITUTION:A propeller 2 is driven by a diesel main engine 1 and an A/C generator 5 is also driven by it through a speed up gear 3 and clutch 4. The output of the A/C generator is converted to electric power of roughly constant frequency through a frequency converter 6 and this power is supplied to the general load (a) in the ship. The output frequency of the generator is transmitted to a controller 12 through the branch line 9 for sending frequency signal that is brached off from the bus bar 8 of the electric power source to control the induction motor 11 of the ship vibration damping device 10. Since the output frequency of the generator is proportional to the speed of the main engine, it is possible to synchronize the damping device with the main engine speed.