MARINERS VOICE

  Types of starters? Dol (direct online starter)-  (5hp) Star delta starter- (5 hp to 20 hp) Auto Transformer - (20 hp to 50hp) Soft starter - (above 50hp) Where its used onboard? Dol  starter Boiler feed pump  Circulating pump  Gear pump  Bilge pump  Fwg distilled pump  Stern lub oil pump.   Star delta starter  Jcw pump (HT and LT) Ballast pump  Sea water pump. Auto Transformer Bow thruster  M/e lo pump  Soft starter Washing machine  Spring drier  Grinder.

WHAT IS WELDING TRANSFORMER?  IT IS A STEP DOWN TRANSFORMER USED TO REDUCE THE VOLTAGE APPROXIMATELY 15V - 45V TO PRODUCE THE CURRENT OF 200- 600AMPS IN SECONDARY WINDING, PRIMARILY WINDING->THIN WIRE AND MORE TURN(BECAUSE LOW CURRENT THIN WIRE CAN CARRY) SECONDARY WINDING ->THICK WIRE LESS TURN(HIGH CURRENT IS PROVIDED) CONSTRUCTION OF WELDING TRANSFORMER? It is a auto Transformer It has a magnetic field core with primary winding which is thin wire and large number if turn. A secondary winding with less turn thick wire. Due to this arrangement its a step down Transformer. So we get less voltage and high current output. DC WELDING TRANSFORMER  is also same working like ac welding Transformer. But in dc welding Transformer rectifier is provided to convert ac, in out put of   secondary winding. Also connect a indictor or filter to get the smooth dc current, This is the construction of welding Transformer. (Please check  the image) Working of welding Transformer? Its is the step dow

  Reason is simple, SURVIVER MAY ASK WHY WE CAN'T SYNCHRONISE SHORE SUPPLY AND GENERATOR ? Both have different frequencies or voltage, While ship's GENERATOR is running we can't close the shore supply circuit breaker, is because interlocking is provided.

  It will reduce the strength of the crankshaft. May possible to occur crack or failure So we drill the hole in a/e Engines. For main engine we use semi build crank shaft .- web and crank pin both are single oice  For a/e engine we use forged crank shaft- its fully moulded type.good fatigue strength.

CYLINDER COOLING/JACKET COOLING FUEL VALVE COOLING PISTON COOLING CHARGE AIR COOLING CYLINDER COOLING/ JACKET COOLING   FRESH WATER OR DISTILLED WATER WILL BE USE . IT WILL INCORPORATED COOLING OF TURBINES IN TURBOCHARGER ENGINE AND EXHAUST VALVE COOLING. FUEL VALVE COOLING FRESH WATER WILL BE USED, IT WILL BE THE SEPARATE SYSTEM  PISTON COOLING USE MAY BE FRESH WATER LUBRICATION OIL OR DISTILLED WATER. IF OIL IS USED IN THIS SYSTEM, ITS GENERALLY COMMON WITH LUBRICATION OIL SYSTEM. CHARGE AIR COOLING SEA WATER WILL BE USED IN THIS SYSTEM  

 Battery Rating: Ampere-hour Battery capacity is usually rated in terms of it's discharge at the 10 hour rate. Example: A 300Amps battery would be expected to provide 30Amps for 10 hours. 

1.Providing proper ventilation inside the compartment.  Independent exhaust fan provided [Non-sparking type; should not produce static charge] Inlet duct should be below battery level. Outlet duct top of the compartment.  [Both batteries emit Hydrogen. Hydrogen is lighter than air. It accumulate on top of  the compartment]  2.By preventing any source of ignition.  No smoking; No naked flames. Battery room lighting must be flame proof (Ex d) Room temperature to be maintained between 15°C-25°C  Battery should never be placed in emergency switchboard room. [chances of sparking due to arching of circuit breakers]  Maintenance tools must be rubberized coating to prevent accidental short circuit.  No metal jugs for filling distilled water inside batteries. Cables should be adequate size and well connected.

Cell tops must be kept clean and dry in order to reduce the risk of corrosion and electrical leakage. Terminals should be kept tight, clean and free of any deposits. The connectors can be coated with petroleum jelly. The cables should be examined from time to time for signs of corrosion. Electrolyte level should be checked and topped up with distilled water to cover the electrodes. Gas vent in the cells should be kept free from blockage by dirt or in case of alkaline batteries from crystallized electrolyte.  Pure distilled water should only be used for topping up. Specific gravity should be measured and temperature correction should be applied. A weekly log of critical parameters to be maintained.  Voltage reading of each cell should be taken while the current is actually flowing. [the voltage of battery on an open circuit is however rather misleading] First aid treatment should be understood and first aid equipment must be available at all times. 

Both batteries emit Hydrogen gas.So no naked lights allowed. Battery is stored in well ventilated room. Battery room should be clean and dry. No smoking board to be displayed. Paint work in room should be acid and alkaline resistance. Acid cells should never be placed near Alkaline cells. Never use Lead-acid batterymaintenance gear to Alkaline battery. Use proper PPE. Insulated spanner should be used to prevent accidental short circuit and may cause spark. First aid equipment should be kept near battery room. Never use the thermometer to measure electrolyte temperature. Accidental damage of thermometer cause explosion. 

Battery room  should be well ventilated, clean and dry. Both type batteries generate gas during charging. So, No smoking, Naked flames in the vicinity of batteries. Steel work and decks adjacent to lead acid batteries should be covered with acid resisting paint and alkali resisting paint used near Ni-Cd cells. Acid cells must never be placed near alkaline cells. Never use Lead-Acid battery maintenance gear to Alkaline battery installation or vice-versa.(e.g Hydrometer, topping up bottle,etc.,)

  MEO CLASS4  25/03/2021 QUESTIONS AND ANSWERS Crank case explosion Main engine one unit exhaust temperature is increased ,what PARAMETERS will you Check,what will be ur action, what can be the reason? BOILER MOUNTINGS AIR IN THE REFER COMPRESSOR,HOW WILL YOU FIND AND WHAT WILL BE THE ACTION. MAIN BEARING AND BOTTOM END BEARING CLEARANCE CRANK CASE EXPLOSION HOW IT WILL HAPPEN? TO MUCH CLEARANCE BETWEEN BEARINGS, OIL FLIMS MAY BREAKDOWN  DIAPHRAGM IS NOT SEALING PROPELY PISTON CROWN IS BROKEN, EXHAUST GAS MAY LEAK TO CRANK CASE, CIRCULATING LUBRICATION OIL NOT PROPER. ENGINE CHAIN DRIVE IS TOO TIGHT. WHICH MAY LEADS TO HOT SPOT. GEARS DONT HAVE PROPER LUBRICATION. PRIMARY EXPLOSION? DUE TO ANY ABOVE REASON HOT SPOT WILL CREATE. WHEN LUBRICATION OIL CONTACT WITH HOTSPOT  OIL BECOMES VAPOUR, AGAIN VAPOUR WILL COME AND  CONTACT WITH THE HOTSPOT, PRIMARY EXPLOSION WILL HAPPENED. SECONDARY EXPLOSION? AFTER THE PRIMARY EXPLOSION, PRESSURE WILL INCREASED INSIDE THE CRANKCASE. NOW CRANKCASE RE

Atomisation: Break up of the liquid fuel into a minute vapour mist. Factors affecting Atomisation :   small orifices of the injector. pressure difference between fuel line and cylinder. Temperature, mass flow rate and viscosity of the fuel. Effect of too high atomisation - After burning Very small fuel particles will not have enough kinetic energy to go through the whole combustion space. Fuel droplets gather near the fuel injector due to resistance from the dense compressed air.  Hence, they will be starved during combustion and after burning will take place. Effect of too low atomisation - Poor combustion  Larger fuel droplets will possess more kinetic energy and get deposited on the liner wall. This causes after burning and poor combustion. Carbon deposits will be seen on the liner walls, side of the piston crown and piston rings.

Boiler water tests: Alkalinity test. [a.Phenopthelin (P) alkalinity test  b.Total (T) alkalinity test ] Chloride test Excess phosphate test pH test  Amerzine test (Hydrazine test) Conductivity test (total dissolve solids test)  Hardness test Purpose of Boiler water Test: To ensure that proper chemical treatment are maintained at all time. To detect the presence of contaminants in the water that may damage the boiler and feed system. How to collect water sample for test? Test sample must be cooled to 25°C with the help of sample cooler. Allow sufficient water to flow through sample line before taking the sample, this will clear it from sedimentation. Let the water overflow from sample bottle to prevent air being trapped. Keep the bottle air tight for testing. If sample is colored or turbid, filter paper should be used for testing. Try to take sample  from same point. Try to avoid the sample to contact with air,  this will change the dissolved Oxygen content. Alkalinity test:   This is t

 Reasons:  Generator lost its residual magnetism. Faulty synchroscope. Faulty Air Circuit Breaker. Loss connection of Automatic Voltage Regulator. (exciter circuit may be open) Faulty power cable. Frequency and Voltage not matching with busbar.

 Brushless alternator  Number of phases : 3 output: 937.5 KVA  volts:  450V  frequency: 60Hz  RPM: 720rpm Insulation : Armature 'F' class  Rating: CONT Power factor:  0.8  Number of pole: 10  Amps: 1203A  Field: F'class  Excitation phase: 3 Excitation output: 21.7KVA  Excitation p.f: 0.95 Exciatation frequency: 84Hz Excitation No. of poles: 4  Excitation volts: 112V  Excitation Amp: 112V  Prime mover: Diesel engine  (this is jz one of the example of  alternator specification. surveyor may ask this specification rarely and he will ask cross  questions about insualtion and its class,power generation, power factor ) 

 Upon 1 hr. notice: Stop FWG and shut valves. Change over to high sea suction. Soot blow Auxiliary boiler, check firing amd put on auto mode. Check all air compressors oil level and put on auto mode. Charge both air bottles and drain any water from bottles and air dryer.  Shut and lock bilge overboard valve and hand over key to cheif engineer. Ensure that all bilge suction valves are shut, however not locked. [Thr security seals may be used to avoid inadvertent opening of any bilge suction valve] Start additional generator for power to mooring machinery, thrusters, deck  water, etc., Shut steam to D.B F.O.T's. Put on sewage plant and changeover valves.  At standby start additional generator as required. At standby record M/E counter, flowmeter readings, L.O sump and cyl. oil tank levels. Ensure adequate manpower available for arrival port. At FWE (finish with engine) Take over control from bridge to ECR and stop auxiliary blower. Open indiactor cocks and engage turning gear. Turn M

 check M/E preheat temperature maintained between 60° - 70°C. Check L.O p/p pr. and temp. within normal parameters. Check crosshead L.O p/p pr. and current within normal parameters. Check JCW p/p pr. and current within normal parameters. Check M/E fuel pr. and viscosity/ temperature. Check all standby pumps selected and reset repose switch. Check control air/Exh. v/v spring air pr. normal. Check Exh. Boiler circulating p/p running and pr. normal. Check stern tube L.O p/p running; pr. normal and sump level OK. Check all air compressors oil level and put on Auto mode. Charge both air bottles and drain water to air bottles and dryer. Confirm M/E L.O sump level normal. Check M/E T/Cs and governor oil levels normal. Check F.O purifier, service tank and drain tank levels. Check L.O purifier running normal. Check steering gear and confirms oil levels normal. Complete all steering gear check with bridge. Start 2nd generator or standby generator and take on load and put necessary breakers ON. T

Back pressure low alarm and shut down Back pressure high alarm and  shut down Feed pressure low alarm and shut down High oil temperature alarm and shut down Low oil temperature alarm and shut down Heavy phase overflow (purifier abnormal alarm will come) Low sealing water pressure  Bowl not open (detected by a current sensing relay) water in oil (detected by transducer)

 Safety valve Pressure gauge Easing gear Air vent Water level indicators (Boiler control panel & ECR panel) Boiler gauge glass Low water level alarm Low low water level alarm and shut down (Trip) High water level alarm Low F.O pressure alarm Low F.O temperature alarm (Trip) High F.O temperature alarm (Trip) Low steam drum pressure alarm  High steam drum pressure alarm (Trip) Forced draught fan stop alarm Flame failure alarm Smoke density high alarm  Note: surveyor will ask what are alarms and what are trips 

Drain valve Unloader  Bursting Disc (Copper disc)  Fusible plug (50% Bi, 30% Tin, 20% Pb) Relief valve L.O low pressure alarm and trip Jacket Cooling water High temperature trip Jacket water no-flow trip High air temperature trip Motor overload trip