Electrical Science and Technology

"Ships on Seas"

The electrical equipment aboard ship is inspected and tested during the complete engine survey which occurs every four years.

Such a survey is prescribed under the Rules and Regulations for the Classification of the Ship (depending where your ship is registered)

The electrical survey guidance in this report is based on the periodical survey regulations of Lloyd’s Register of Shipping, London.

Other classification societies have their own rules which although similar to Lloyd’s,shouldbe consulted prior to an electrical survey.

Electrical equipment and services aboard ship must also meet the minimum standards by various national and international organization.

For UMS operation, a survey of the associated alarms, controls and fire detection is required.

For tankers/gas carriers and other ships transporting flammable cargo, an additional survey of all electrical equipment in hazardous areas is carried out during each docking survey and annual survey.

The surveyorwill require that main and emergency generators are clean, respond correctly to controls and load changes, and show stable operation when required to run in parallel with other generators.

Generator windings on stator and rotor must be free of:

 A visual check will be made for any obvious deterioration, abrasion, or cracking of the insulation around the end winding coils of the stator.

An insulation testto earth and between stator phase windings (if neutral point can be disconnected at the terminal box) should be carried out while the machine is still hot after running on load.

 Remember to disconnect all AVR equipment, instrument connections and generator heater supplies when testing for IR.Special attention to the contact surface of any commutatoror slip-rings is required.

Generator running test, on load, should confirm the proper operation of governor and AVR controls with correct voltage, frequency, and current values indicated on the generator control panels.

Governor droop (typically 4%)and its response to load changes must be within the declared specification for the prime mover/generator combination.

A visual examination of circuit-breaker in main, emergency and section boards will usually precede operational tests.

The surveyor will particularly check the condition of main, arcing, and auxiliary contacts for signs of wear, misalignment and overheating.

Arc chutes must be clean, free of arc debris and correctly aligned.

 Test on a circuit-breaker will include ‘close’ and ‘trip’ operations while in its ‘isolated’ position (i.e. not connected in circuit).Over-current trips are typically set for 125% of full load current with a typical time delay of 20 sec. but this can vary to suit the thermal capacity of the generator. 

 Switchboards and fittings

 An obvious survey requirement for any switchboard, section board or distribution board is that they are clean. This includes all internal surfaces as well as the external pane surfaces, instrument faces and control switches.

A thorough cleaning job on the inside of the main switchboard can only be safely carried out when the board is completely ‘dead’ (all generators stopped and prime movers locked OFF

 Feeder isolator blades and fuse holder contacts must be checked for any mechanical wear or damage due to overheating or arcing at the contacts.

Operational test on a main switchboard under this heading will focus on the synchronizing controls and generator protection relays such as reverse power and preferential load shedding trips.

Typical reverse power trip settings may be 10-15% of generator power rating, with a time delay of 3-5 sec. for a diesel drive.  


Would IR reading of 0.5 MΩ to earth be acceptable?


Although a minimum of 1MΩ is generally specified for new equipment, Lloyd’s rules suggest that 0.1 MΩis acceptable. However, most surveyors would insist on at least 2kΩ/volt, i.e. 440kΩ, say, 0.5MΩ as a reasonable minimum value for a 440V generator. 


What is the point of earthingone end of a current transformer secondary winding?


Should the insulation between primary and secondary breakdown, the secondary circuit can be raised to full primary voltage; e.g. 440V above earth which should damage the secondary insulation with a serious risk to personnel. By earthingone end of the CT, the circuit is ‘anchored’ to zero volts. As a bonus, the earth connection will allow such a fault to be detected on the earth fault monitor.


What are the functions of EPR or butyl and PSP or CSP?


EPR or butyl rubber are good electrical insulators but are not mechanically strong or resistant to oil. This is why a sheath of PCP or CSP which is stronger and has greater oil and fire resistance is fitted around the inner insulation.

Please check your understanding on basic electrical engineering.

The author is a licensed engineer. He is an advocate of corruption awareness. He believe that thru awareness of the consequences of corruption--the community will be awaken and will not allow any form of corruption to engulf their very existence.



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I learned a lot, thanks sir.

sir i've tried to understand the article and also found the page: http://magelhaes.hzs.be/willem/site/safety/Neutral%20earthing%20of%20marine%20electrical%20power%20systems.pdf You may also consider that: If an earth fault occurs in an "earthed distribution system", it would be equivalent to a "short-circuit" fault across the load via ship's hull. The resulting large earth fault current will immediately "blow-up" the fuses in the line. Thus the equipment is isolated from the supply and thus rendered safe. This may result in hazardous situation, if the equipment is classed as "essential" for eg: steering gear. Thus the "earthed distribution system" requires only one earth fault on the line conductor to cause an earth fault current to flow The earth fault occurs in "insulated neutral distribution system", will not cause any equipment to go out of operation and thus maintains the continuity of operation of the equipment. This point is to be noted," the machinery still continues to operate". Thus a single earth fault will not provide a complete circuit for the faultcurrent to flow. If a second earth fault occurs, then the two earth faults together would be equivalent to a short circuit fault ( via ships hull) thus resulting large current would operate the protection devices, cause disconnection of, perhaps, essential services creating a risk to the safety of the ship. If you mean "earthing" to be "grounding" from an electrical point of view, then "grounding" means to provide a return path for free electrons to "ground", or simply, a return path to the negative polarity of a voltage source. Hence, the metal chassis of a car, train, ship or airplane is a good "ground" or a return path for electrons to travel. SIR i may then conclude that As with Earth grounds, this ground is never used to carry returning currents of a power line, because resistances between various structural parts might not be low, and then a dangerous voltage drop might be formed between different parts of the vehicle. It's also not used to carry small signals (such as for microphones), for a similar reason: random currents in the ground shell will cause plenty of noise and ruin the signal quality. On automobiles the whole chassis is taken as local ground, and used for returning power currents too. These are the reasons the practice might be acceptable in cars: usually a car chassis must be very well bonded together, and low cost is important compared with safety, and the voltage is not very high, and probably others... Maybe this practice is one of the reasons that cars are considered to be fairly noisy electrical environments. Ground does not always have to be connected to Earth. In cars, airplanes... even portable radios... an artificial ground is established. It is usually the chassis of the radio or car. It is treated just like a ground attached to the earth even if it does not have true ground potential. I am not that familiar with the ships sir sooo... I would still need to find out more... thank you for the points and the info sir!!! thumbs up

that was impressive sir. simplifying things that are found on the pages of the book. :)

simplified lectures of electrical equipment on board ships. this will help in my studies. this is pretty impressive. thank you sir!

As an engine cadet, this lecture help me in my preparation for my upcoming shipboard training. Hope you can upload more articles that will surely help me and other engine cadet that will board their respective vessels. Thank you Sir!

Sir thank you for the superb information, I know for sure that it will help me when I'll board an international vessel in the next few months.thanks a lot

Sir Thanks for this Information! Knowing that most of the ships nowadays are required to have wi fi on board, we may easily access this information if we have or we need some references. In this way we can still learn from you sir! well appreciated sir! :) More topics/Lessons to come sir.

Pretty much appreciated sir. Thanks a lot.

Sir please explain the importance of governor droop?

i am very impress for the effort of the writer, he is really giving all of his effort to teach his students the importance of electrotechnology :)

thank you sir, i learned a lot regarding electrical equipment and electrical survey guidance :D

This article is very comprehensive. The lengthy and very difficult topic was reduced to such level.It has given the readers the idea of how and why electrical system on board is inspected thoroughly. there different rules for inspection and it depends on the classification societies. the article also highlighted the idea that the generator windings is supposed to be free from dust, oil, moisture since it is a part of the inspection. the article also provided a very good explanation about .5M ohms is acceptable as the minimum standard. I love this article.

I believe this isn't a simple topic at all. But, the explanation has been presented in a way that is easy to understand and relate to, especially in our chosen profession. The Q&A portion is also a very helpful tool in aiding the questions that may have lingered at the back of the readers mind while reading the article. Thanks for the wonderful read sir! :D

Now for this one, it has more insight than the previous one I read, but I saw some parts in this one that is also on the last one. That is all I could comment on this one. Thank you sir "J

The article is so encompassing... I really learned a lot about electrical equipment and electrical survey guidance. Looking forward for more articles. ;)

the topic being discussed will help a lot for us, especially those who will go on board the ship. the discussion is light, that it can be easily understood by anyone. i'm just wondering why the inspection is being done every four years. i think it is better if the survey will be conducted every 2 years. since safety is the primary concern aboard ship, and a ship is typically made by a huge conductor, and we are inside that vessel. what if in a span of 2 years, the electrical system is being damaged or destroyed, without the noticed of anyone, are we still going to wait for 4 years? i'm wondering why... Good day!

the topic was discussed in a way that we would able to understand and relate it in our profession . I've learned that checking of the insulation around the end winding coils of the stator is only through visual examination . thank you sir.!

Modern ships are increasingly dependent upon the electrical and control engineering installations for their operation. There is also greater use and reliance on complex computer-based systems. It is therefore essential that seagoing and shore-based staff have a good appreciation of such systems, ensuring that they are maintained in an efficient operational and safe condition. -Octaviano NOSHIRO

It is good to see the term "UMS(unattended machinery space)".UMS is very common in ship nowadays. It consist of many alarms, detector, switches, relay and light. This topic may helps us aboard ship and it enhances our knowledge in electric matter on board.

sir, thank you for all the efforts you have given to all of us. we appreciate it. all the knowledge you shared to us will help us when we board our own commercial vessels for shipboard training.

Electrical equipment includes any machine powered by electricity. They usually consists of an enclosure, a variety of electrical components, and often a power switch. electrical equipment on board are very delicate and it is important to learn and master all of its operation and safety process. Electrical safety is crucial in a marine environment because of potential dangers of shock, electrical arcs and electrical blast, which are especially hazardous in the confined spaces often found aboard boats. Good design and safety practices can help prevent any electrical accidents on board ship. For safety purposes in working on electrical equipment on board ships, all workers should have adequate protective gear including rubber gloves, hard hats, eye protection, insulated hand tools and voltage measuring instruments. Clear procedures should be established for de-energizing equipment. In addition, workers should strictly observe all clearance distances around electrical equipment. In short wear the proper PPE in order to prevent this hazards that might harm you.. SAFETY FIRST!!!

This article is very helpful to students and cadets taking up engineering courses especially in the fields of Marine and Electrical. While it is more focused on the systems on a ship, Electrical Engineering students may still find this useful in their own field of study. Thank you for sharing your knowledge with us Sir. \m/

in learning something we must first know the basics and this article will help us in our shipboard applications.

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