10 February 2018
23 February 2017
ASSESMENT ETO MMD QUESTIONS ORAL
1) Black Pen (compulsory)
2) Paper punch (recommended)
3) Stick Glue (recommended)
4) Stick File (Compulsory, Please purchase from Mangalam store saying you require file for ETO assessment)
5) Correction Pen (only if any mistake in writing)
Please carry two color passport size photo (recently taken). Please take photos in formal dress only preferably with tie. No uniform dress or with T-shirt or casual dress.
Documents Required as per Assessment checklist:
1) CDC including relevant pages of sea service - Compulsory
2) Passport (all stamped pages) - compulsory
3) INDOS Certificate - Compulsory
4) Educational Qualification - Compulsory
5) Bridging Course / ETO Course (as applicable) - Not required for Candidate who has 12 months Rank experience prior 1 Jan 2012 i.e. CAT 1, BETO course Compulsory for Candidate who has 12 months experience prior 1st July 2013 i.e., CAT 2, 4 Months DG approved ETO course compulsory for candidate who doesn't have 12 months experience prior 1st July 2013 i.e., CAT 3.
6) Approved Workshop Certificate - NA
7) Validity page of RPSL No. issued to the company - Letter issued from the company on company letter head indicating RPSL Number
8) Sea Service Testimonials, Indicating Sea Time and Propelling Days duly signed by Chief Engineer and Master of the Vessel - Not Compulsory. Submit only if you have sea service testimonial Or else Not required.
9) Article of Agreement (Only for Indian Flag vessels above 200 GRT) - Applicable for candidate sailing on Indian Flag ship. For other Flag, NA
10) Sea Service Extract - Only for Ex-Navy Candidate. For Other, NA
11) STCW Course - Compulsory, preferably refresher course as per STCW 2010
12) Certificate of Proficiency in Security Training For Seafarers with Designated Security Duties (STSDSD) - Compulsory
13) Valid Medical Fitness Certificate in ILO Form (DGS Approved Doctor) - Compulsory, Can be obtained near MMD itself
14) Seafarers Profile (Updated) - Compulsory Only DGS Seafarer Profile required.
Please carry original as well as a photocopy for the above documents. Kindly self-attest all photocopy including Seafarer profile.
Original Sea Service letter issued by the Owner or the company on Company letter head addressing
The Principal Officer,
MMD (Corresponding office for example, Mumbai, cochin, Chennai or Kolkata)
Procedure for Assessment (with respect to MMD, Mumbai):
1) Please go neatly dressed with all original documents and photocopy.
2) MMD, Mumbai office opens by 9.30 am. So, candidate can go there just before 9.30 am. There will be no queue system (like first come first serve). Every candidate will be called with name with respect to Serial Number bases as per the assessment list
3) Candidate will be called to the examination Hall and will be seated.
4) Candidate will be called with name, at that time candidate will be given application form with serial code on it, ETO Checklist and challan form.
5) Once every candidate has the application form, one of the staff member will explain you step by step about how to fill the application form. Application form to be filled in Black pen only.
6) After he explains how to fill the application form. Candidate will be given sufficient time to fill the application form as well as Challan form has to be filled. Challan form has four copies in it. Challan and money has to be deposited to the bank.
7) Kindly note that the bank accepts cash only. No card.
8) Fee is Rs 3000 for assessment, Rs 4500 for written, Rs4500 for oral and Rs 50 for bank charges. For candidate with Oral, only have to pay for Assessment and oral i.e., Rs 7550. For candidate with orals and written fee is Rs 12050.
9) Assessment will only start if the candidate has paid the fee and taken the challan. Once the fee is paid, bank will return two copy of challan, one for MMD and One for you reference. Other two copies will be retained by the bank.
10) After application form is filled, fee is paid and challan is obtained. Every candidate will be called with name as per serial number.
11) All the documents will be verified. Sea time will be verified with CDC, Sea time letter issued by company. Make sure the Sea time in CDC and company letter matches.
12) Candidate who all are applicable for orals has to mention only 12 months sea time to satisfy the category under which they come. No need to filled all the sea time.
13) Once the sea time is satisfied as per the category written exception will be given and a staff member with verified and sign it.
14) Once it is signed by the staff member, candidate will be asked to visit superintendent of examiner office where again the examiner will verify candidate sea time and applicable course ( BETO/ ETO). Once he is satisfied, he will sign the application form.
15) Once successful completion of above process, candidate has to write their name, application number, phone number in a register book and leave the office.
Hope I have given sufficient details for assessment procedure, if anyone has any doubt, please feel free to contact me.
7 January 2017
MMD QUESTIONS ORAL
Oral on Marine Electro Technology Part - 3
1. Why AC is popular on board ship ?
- Smaller, lighter and compact machine size, for a given kW
- High power and high voltage AC generator can be easily manufactured
- Voltage can be raised or lowered by transformer
- AC can be easily converted to DC
2. Precautions while working on electrical machinery ?
- Switch off the main switch
- Out mechanical lock on
- Take out fuse
- Put a signboard “Man Working on Line”
- Use LOTO (Lock out Take out)
3. What is AVR ?
- A.V.R or Automatic Voltage Regulators are used in conjuction with generator for controlling the terminal voltage to give a steady voltage under varying load.
- It senses and controls an A.C generator’s output voltage within (+ or -) 1 to 2%.
4. What are the types of A.V. R ?
- Carbon pile regulator
- Vibrating contact regulator
- Static A.V. R.
- Rotating sector
- Multi contact
- Magnetic amplifier
- Electronic amplifier
5. Carbon Pile Regulator (AVR)
- A resistance from a carbon pile (stack), which is varied by pressure changes, controls the current flow through exciter shunt field
- Pressure is applied by springs and relieved by magnetic field strength of electromagnetic coil
- Current for electromagnetic coil is supplied from alternator output to switchboard
- AVR is designed such that variations in alternator voltage, due to load change will effect strength of electromagnetic coil and hence alters carbon pile resistance
- When alternator voltage is low, spring exerts greater pressure and carbon pile resistance becomes low, so more currents flow through exciter shunt field and then increase the output voltage
- When Alternator voltage is high electromagnetic coil relieves pressure on carbon pile and resistance becomes high. Less current flows through exciter shunt field and decreases the voltage (Strength of Electromagnetic coil relieves spring pressure on carbon pile)
6. What is rectifier ?
- It is an electric device or circuit capable to allow an A.C current to be converted to D.C current.
7.What is excitation ?
- To supply and control the correct D.C current for the rotor pole winding to produce the required generator A.C output voltages.
- Production of an electromagnetic field of a generator by supplying exciting current for magnetizing the field magnet
- For excitation, DC is used because DC produces constant rate of magnetic flux
- Continually regulated to maintain the generator output voltages as the load demand fluctuates.
- The source, which generates the field current for excitation of field magnets.
9. Equalizing bar
- Equaliser is a low resistance circuit, connected across armature ends of series coils of parallel compound generators, via a special bar in switchboard
- Equaliser is fitted to stabilize parallel operation of compound Dc generators.
10. Rotary converter
- A rotating diode to convert AC to DC current for alternator excitation
- Synchronous motor and generator combined unit
- Filed and armature coils are similar to DC generator, except that slip rings are located on the end of the shaft opposite to commutator
- AC turns the converter (as synchronous motor) and DC is taken from commutator brush
11. Procedure for alternator overhaul ?
- Shut down the generator prime mover and lock off the starting system.
- Lock off the circuit breaker and isolated the alternator electric heater. Tag the label on the switchboard.
- Inspect the tightness of terminal connection and insulation.
- Check the bearing oil level and condition.
- Clean the cooling air intake filter and exhaust opening.
- Clean the rotor and stator windings by means of vacuum cleaner with rubber hose and nozzle.
- If the oil is deposited on the surface of winding, open the drain plug and then removed by special degreasing liquids. (Electro cleaner)
- Measure the air gap clearance between rotor and stator. (Carefully at lower part)
- Baking the alternator with lamp. Keep a temp not more than 43°C
- Disconnect the neutral point from the terminal box.
- Measure insulation resistance between – rotor to earth, phase to earth, stator to earth, phase to phase
- It is must at least one mega-ohm, if mega reading has reasonable value, the windings are to be covered with high quality air drying insulation varnish.
After maintenance work
- Reassemble all necessary parts.
- Check no load running, the synchronizing and loading.
- On load, practically check for excessive temperature rises and load sharing stability when running in parallel.
12. Inspection and Maintenance of Battery Room
- Battery installation and its charging rectifier checked.
- Battery room environment must be dry and well ventilated.
- Battery tops shall be clean and dry, and terminal nuts must be tight and a smear of petroleum jelly applied to prevent corrosion.
- Electrolyte at proper level, and shall have correct value of specific gravity by checking with a hydrometer.
- Rubber gloves and goggles used when handling electrolyte.
- Charging equipment checked for dirt, overheating, loose connection and correct functioning of indicators.
- Ventilation arrangement for battery locker checked. Battery installation of both lead acid and alkaline needs good ventilation.
- Since both type generates hydrogen gas during charging, no smoking and naked light allowed.
- Steel works and decks adjacent to lead acid battery, should be painted with acid proof paint. [For Cad-Ni cell, alkaline resistance paints].
13. Battery Room Safety Arrangement
Safety is provided by
- Proper ventilation
- Prevention of heat source for ignition
- Independent exhaust fan provided
- Inlet duct should be below battery level, and outlet at top of the compartment
Prevention of heat source for ignition
- No naked light and no smoking
- Uses of externally fitted light or flameproof light
- Cables of adequate size and they are well connected
- Never place Emergency Switchboard in this room
- Use insulated spanner and plastic jug for distilled water, to prevent short circuit
- Room temperature, maintained at 15 ~ 25 °C
14. Nickel Cadmium battery [alkaline battery]
- + ve plate is Nickel hydroxide + graphite
- –ve plate is Cadmium + Iron
- Electrolyte is Potasssium hydroxide solution (strong alkaline)
- Normal specific gravity [1.21] does not change with charging or recharging
- But specific gravity of electrolyte gradually decrease, and electrolyte should be renewed when specific gravity becomes [1.160]
- It is a sealed battery, thus no gassing during charging
- Very low open circuit losses, but requires 67% more cells than Lead Acid battery [1.2 V per cell and when fully charged 1.7 V per cell]
- Not harmful when overcharged
- Left for long period, either fully charged or fully discharged, without deterioration
- Better mechanical strength and durability than lead acid battery
- High initial cost but longer life
15. Lead Acid Battery
- + ve plate is Lead Peroxide [chocolate brown]
- – ve plate is Spongy Lead [slate gray colour]
- Electrolyte is H2SO4 , specific gravity 1.8 when fully charged, renew when specific gravity is 1.110.
- 1.8 V per cell when fully charged 2 V per cell
- When undercharge, + ve plates are pale brown or yellowish, instead of deep chocolate and very difficult to convert back to normal form
- Efficiency (watt hour efficiency) is higher than Alkaline Cells
16. How do you know when the battery is full charge ?
- It can be known by measuring the electrolyte specific gravity by using hydrometer.
- If fully charge it has a specific gravity of about (1.27 – 1.285), hydrometer scale 1270 to 1285
- If fully discharge which fall to a specific gravity of 1.1 (1100)
17. How can you know battery is over charge ? Effect of overcharge ?
- When battery is overcharged bubbles will form at the surface, the current flowing into the cell causes breakdown or electrolysis of water in the electrolyte.
- Both hydrogen and oxygen are evolved and released through cell vent caps into the battery compartment.
- There is an explosion risk if hydrogen is allowed to accumulate. (4% of H2 in air).
18. What happens when lead acid battery is overcharged ?
- Overheating cause buckling of plates
- Internal short circuit
- Sludge formed at the bottom of cells (lead peroxide)
- Battery may be ruined
- Lower the capacity
19. What happens when lead acid battery is undercharged ?
- Over discharging
- + ve plates are pale brown or yellowish, instead of deep chocolate
- - ve plates, almost white colour
- Falling of voltage 1.8 V / cell, and specific gravity of H2SO4 1.15
- Liberation of hydrogen ions at – ve electrode (cathode) and that will decrease the current flow.
18 December 2016
MMD QUESTIONS ORAL
Oral on Marine Electro Technology Part - 2
1. What is induction motor ?
It is a motor which run at a speed below that of the rotating magnetic field.
Types are squirrel cage induction motor and slip ring induction motor.
2. Squirrel cage induction motor
- Most widely used of all types of AC motors, due to simplicity, strength of construction and ease of maintenance
- Made up of two main parts, rotor and stator and no direct electrical connection between them.
- No wire winding or slip rings.
- Rotor has a series of plain bars (copper or Al) running in slots the length of the iron core
- Each end of the bar is brazed into 2 heavy copper rings, one at each end. Those bars form a cage, that looks like squirrel cage
- Stator has 3 separate windings supplied from a 3 phase AC supply
- Phase difference 120 and number of poles 2, 4, 6 or more, depending on speed required
3. Difference between Synchronous Motor and Induction Motor ?
- Synchronous motor is almost exactly the same as an alternator
- Induction motor cannot run normally at synchronous speed. It has slip.
4. What are AC motor overloads protections ?
- Magnetic overload relay
- Thermal overload relay
- Built-in protective device
5. Causes of motor overheat ?
- Motor running at overload
- One phase failure (single phasing)
- Defective cooling fan blades
- Bearing failure
- Poor ventilation
6. When phase failure occur, A.C motor run or not ?
- When motor is running, the motor keep on running but over load and over heat will occur.
- When motor is starting, the motor cannot run.
7. What is moving iron instruments ?
It is an instrument suitable for measuring A.C voltage or current as well as D.C voltage or current.
8. What is potentiometer ?
It is an instrument which is used to measure or adjust the potential difference in the circuit.
9. What is moving coil instruments ?
It is an instrument used for D.C only and as voltmeter or ammeter.
10. What is Static Electricity ?
- Electricity at rest instead of in motion
- Electric charges may be induced by friction or atmosphere effect
11. How to prevent Static Electricity hazards in oil tanker ?
Earthing device, earth bond across flanges on pipeline
12. What are the causes and effects of Single phasing in motors ?
- Single phasing occurs when one of the 3 phase circuits is opened, hence the remaining circuits carry excess current.
- One phase of the circuits becomes open, due to blown fuse, faulty contactor, or broken wire.
- It prevents a motor from starting, but a running motor may continue to run with this fault.
- For a running motor, it can be detected by overloaded device in supply line, or overheating.
- For an idle motor, it cannot be started.
- Due to single phasing, overheating in a stalled or running motor will cause, burnt out overloaded coil.
13. What is residual magnetism ?
- Magnetism remaining in the fields of a generator, after exciting current is cut off.
- Residual magnetism is essential for initial generation of current, necessary for further build up of shunt field strength.
- Generator may fail to excite, if there is loss or reversal of residual magnetism of the pole.
14. What action, when generator fails to excite ?
- Pass a current through shunt field coil in correct direction
- Correct direction means the current will re-magnetise the iron core in the right way
- Current for restoration can be obtained from another DC generator or from a battery.
- If battery is used fro re-magnetising: A 12 V battery is connected [exclusively] across shunt field coil with the machine stopped
- Current flow in right direction, for a few seconds, only will establish the field.
- During this time faulty generator must be in stopped position.
15. What are windlass safety devices ?
- Emergency stop
- Overload trip
- Over speed trip
- Mechanical break
- Slipping clutch for over load, to prevent any undesirable damage such as hull damage due to anchor and rope brake out.
16. What is Slipping Clutch in windlass ?
- Slipping clutch is commonly fitted between prime mover and gearing
- It is incorporated with motor, magnetic brake and drive shaft
- Set to slip at approximately 133% of full load torque
- Letting go or dropping speed is controlled by friction brake
- Hauling speed is 0.15 m/sec
17. Why Slipping Clutch is fitted in windlass ?
- In windlass, undue stresses must not be applied to chain cable and machinery
- Without slipping cultch, excessive stresses could be applied to cable, by armature momentum, by sudden obstruction when heaving, or when bringing the anchor into hawsepipe.
- Fitted also to avoid inertia of prime mover being transmitted to windlass machinery in the event of shock loading on cable, when anchor is being housed
- When ship is riding at anchor, bow stopper prevents the strain for windlass
18. Explain electric breaking system in marine machinery ?
- When electric deck motor is used for lowering or lifting load, electric brake system is used. All brakes are failsafe types.
- In the event of power failure, brake automatically applied, thus preventing the load running back. A number of brake pads [free to move] are located in carrier, which is keyed to motor shaft.
- Armature plate applies pressure to brake pads, by means of a number of springs, to force against friction surface of back plate, so that it prevents the motor shaft from turning.
- When energized, armature plate is attached to magnet, thus releasing the thrust pressure and allowing the shaft to rotate
19. What is synchroscope ?
- An instrument fitted at the main switchboard which indicates when two electrical supplies are in synchronism and can be paralleled.
- An instrument, which indicates that, voltages, frequencies and phase angle of two electrical supplies of running machine and incoming machine, are in synchronism and can be paralleled.
- Synchroscope should not be left in circuit for more than 20 minutes as it cannot continuously rotate.
- Synchroscope is a small motor with coils on the two poles connected across red and yellow phase of the incoming machine and the armature winding supplied from the red and yellow switchboard bus bars.
20. What is the synchronizing ?
The process of bring the voltage, frequency and phase angle of electrical supplies into line in order to be paralleled and share the loads.
21. Explain Synchronising methods ?
- Synchroscope is the main method
- Back-up methods are: Lamp dark method
- Lamp bright method
- Rotating lamp method or Sequence methods (preferable)
22. Explain Rotating lamp method or Sequence method ?
- One of the lamps known as key lamp is connected in one phase
- Other two lamps are cross-connected
- If two frequencies differ, lamps will bright up in rotation. Clockwise indicates incoming machine is fast, and counter-clockwise indicates it is slow
- Synchronising moment is when key lamp is dark and other two lamps equally bright
- If phase rotation is wrong, all lamps will become bright and dark together.
- Remedy is to interchange any two phase connections
23. How to parallel the two generator with the aid of synchroscope on ships ?
- All meters and indicators must have in good working order.
- Start the incoming generator with the correct staring procedure.
- Check the working condition by readings pressure gauges, thermometer and audible and visual.
- Watch for a minutes until prime mover come to stable.
- Check the voltage of existing and incoming generator on the switchboard, check trip if have reset.
- Move the selector switch to incoming generator. At that time, synchroscope pointer will rotate clockwise or counter clockwise direction.
- Check the frequency and voltage of existing and incoming.
- Carry out the adjustment by means of speed adjuster of prime mover to obtain the condition such that synchroscope pointer rotate in the clockwise direction at a speed of about 4sec/rev.
- Close the circuit breaker of incoming generator when the pointer reaches just before 12’ O clock position.
- Made off the selector switch.
- Made load shearing the two generators by the speed adjuster of generator.
24. How do you parallel the two generators if synchroscope is out of order ?
- If synchroscope is out of order, the two generators can be paralleled by emergency synchronizing lamps with sequence method.
- The lamps are fitted as triangle forms, one on top and two on bottom.
- To make parallel, reset if any trip
- Move the selector switch to incoming generator. At that time, synchronizing lamps will give bright and dark sequence rotate clockwise or counter clockwise direction.
- Check the frequency and voltage of existing and incoming.
- Carry out the adjustment by means of speed adjuster of prime mover to obtain the required frequency.
- Adjust the speed to meet the slow clockwise direction.
- Incoming machine breaker is closed by hand when the top lamp (key lamp) dark and the both bottom lamps are equal brightness.
- Off the selector switch and make load sharing the two generators by speed adjusting.
25. How do you monitor the correct instant for synchronizing without the aid of synchroscope or synchronizing lamps ?
- It can be synchronized with 500V voltmeter as follow.
- Connect a pair of 500V voltmeter probes across the one phase of the incoming machine circuit breaker and bus bar.
- Adjust the generator speed until the voltmeter slowly fluctuates from zero to maximum.
- Close the breaker when the voltmeter passes through zero.
26. Can you parallel the load of main G/E with emergency G/E and shore supply ?
It cannot paralleled, circuit breaker interlocks are arranged in this system.
27. What are the generator safety devices ?
- Over speed trip
- L.O low pressure trip and alarm
- F.O low pressure alarm
- Jacket water high temperature alarm
- Jacket water high temperature trip
- Pressure gauge
- L.O high temperature alarm
- Dip stick
- Crankcase relief valve
28. Methods of armature reaction compensation ?
- By fitting inter poles between the main poles
- By fitting carbon brush rocker
- By fitting neutralizing winding
Oral Guide by – MIN ZAR TAR
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