IT IS THE ALLAH WHO SUBJECTED THE SEA TO YOU.THAT SHIP MAY SAIL THROUGH IT BY HIS COMMAND ,THAT

YE MAY SEEK OF HIS BOUNTY,AND THAT YE MAY BE GRATEFUL

(Al-Quran)

Marine Engineering

DC and AC motors

Motors parts

• Field system or stator

• Armature or rotor

DC motors

• Direct current motors is generally divided into three categoriesShunt wound motorSeries wound motorCompound wound motor

• We can control motor speed by changing the voltage across field or armature winding. For this purpose the resistor is employ across series or shunt winding

Shunt Wound Motor

• The shunt is attach in parallel with the motors

• Speed drops but little with increasing load

Series wound motor

• Series falls heavily with increasing load starting torque is high

• Speed falls heavily with increasing load starting torque is high

Compound wound motor

• Shunt and series both are attach in compound motor

• This motor can function of shunt as well as series motor.

Interpoles

In addition to the main field, across field due to current in armature winding effects the field distribution under poles. This affect can be neutralized either by shuffling the brushes from zone or belt by interpoles.

Author Introduction

ZEESHAN AHMED, Marine Engineer. After doing FSc(pre-engineering) from PAF(fazaia) intermediate college Lahore cantt. I joined Pakistan Marine Academy and choose Marine engineering branch. Two years of training at academy (practical + theoretical) we learned a lot of thing like CNC (computerize numeric code), trained on various models (like control valve, solenoid valve, flow meter, refrigeration system,

CPP propeller, Main engine model (TWO stroke), Boiler model (water tube) ……………………………….. in GEK (general engineering knowledge) lab, Mechanical and physics lab, Engineering workshop. ETC . After two years, we joined PNSC workshop for the training of ONE year Industrial training. That was also the golden time where we learnt a lot of things at different shops as well as onboard (repairing and watch keeping). I learn many thing on tanker E.g. MT Johar (learn how to dismantle turbine rotor from casing and what are the precautionary measurement while working on turbine, learn how to change the diaphragm(stationary blade) Plate type heat exchanger gasket change, shell and tube Cooler Anode replacement and (Cont.)

Introduction (cont.)cleaning of SALT WATER tubes etc.) , MT Swat (major thing which I learn in Swat is how to dismantle head of main unit and copper gasket replacement with a minor facing defect which is found during overhauling which is filled and faced by Belzona) , MT Lahore(About the DEAD MAN ALARM, Alpha lubricator for Cylinder Main Engine Unit, Pump operation and watch keeping), MT Quetta(Auto load sharing of Generator Set, MT Karachi (Dry washing of the main engine turbocharger with granules, water washing of IG Fan of Inert Gas system, sludge removal of from purifier(centrifuge) etc., . One thing I want to added is that the trend in ship building is more toward based on electronic and electrical application. So a marine engineer must strong in automation, instrumentation and control system. PLC (programmable and logic control) and SCADA (supervisory central access and data acquisition) are the upcoming technology that are using on modern ship. The latest engine of MAN B&W is based on Camless technology. Chain is removed ; fuel pump and exhaust valve actuation is control by hydraulic servo(lub) oil which is driven by Axial piston pump mounted on the Fly wheel.

Regards,

Z.A.

Author contact information

• zeetec4@yahoo/gmail/hotmail.comzeetec4@yahoo/gmail/hotmail.com

Social networking sites• Facebook: mariner46

Website: zeetec4.googlepages.com

Any question and suggestion are welcome