The megohmmeter (commonly called a megger in the field) is used to measure the resistance of insulation in megohms (thousands of ohms). Test results indicate the presence of dirt, moisture, and insulation deterioration. Megohmmeter instruction manuals provide detailed information about connecting to and testing various types of equipment. The following sections provide general guidance […] Read more
Besides the ordinary resistors we have been looking at so far there are also resistors with quite special properties. We are not going to bury ourselves in their characteristics but merely have them presented. One which undoubtedly is known to everybody from Danfoss’ products programme is the photo resistor, the little “glass eye” which is […] Read more
Overheating problem on Ship Extremes of temperature will affect the performance and the effective life of any electrical apparatus. Devices which depend on electromagnetic operation by shunt coils will find that the resistance of the coil increases with temperature and so with less current, the field strength ‘H’ is reduced ( H=NI where N is […] Read more
The central section of the main switchboard is used for the control of the main generators. The switchgear cubicles on either side of the generator panels are used for essential services and flanking these are the grouped motor starter panels. Handles for opening the doors on switchboard cubicles are usually linked (or interlocked) to an isolating-switch. […] Read more
Marine electricians are responsible for installing and maintaining electrical systems and/or equipment on ships and boats. They typically work at sea... Read more
Occasionally a transformer winding becomes completely shorted. In most cases, this activates the overcurrent-protective device (circuit breaker or fus... Read more
Sometimes a few turns in the secondary winding of a transformer experience a partial short, which in turn causes a voltage drop across the secondary.... Read more
Dry-type transformers are a part of most electrical installations. They range in size from small doorbell transformers to three-phase 25-kVA units ins... Read more
Electrical Engineer on Container Ship at. Golf Marine Ltd. Salary:5500$ per month Duration of contra... Read more
Manned engine-rooms are rare nowadays. Modern automation systems such as remote control and alarm and monitoring systems make it possible to operate most engine-rooms unmanned, at least part of the time. In day-time engineers can execute planned maintenance and repairs or replacement of defective parts. Because engine-rooms are usually warm, damp and noisy, an un-manned […] Read more
With two sides of an ABS-R2 power system in parallel, the ship would have no power if both sides have failed. For such a system, we multiply the unreliability (probability of failure) of each side to obtain the unreliability of the total system Parallel connection on ship system Total parallel ship system unreliability = 0.05 […] Read more
There are two basic types of pushbuttons on ship electrical system which are momentary and maintained. A normally open momentary pushbutton (S1,S2) only remains closed while the button is pressed. A normally closed momentary pushbutton only remains open while pressed. A maintained pushbutton (S3,S4) will fasten and remain in the changed state when pressed. Read more
Block diagrams represent the main arrangements and inter relationships between either different systems or different modules within one system. They create a general overview of the entire plant. Units within a plant, shown in blocks, are connected by cables with their corresponding ship cable numbers voltage and number of cores. Block references consist of: unit […] Read more
The induction motor has two main components, the stator and the rotor. The stator carries three separate insulated phase windings which are spaced 120 degree (electrical) apart and lying in slots cut into a laminated steel magnetic core. This type of stator winding is similar to the construction used for an a.c. generator. The ends […] Read more
When preparing a ship spares order, the reference numbers or letters should not be ignored, particularly If the requested type of relay is not available from the supplier and another vendor is being asked for an alternative. To avoid mistakes it is suggested that the relay order form should include the following information:• Relay manufacturer• […] Read more
To successfully carry out the various test procedures suggested in this manual, certain test instruments are essential. The following lists detail the basic requirements in this respect. It should be noted that in addition to these instruments a comprehensive kit of tools is also essential. For fault finding purposes this need not include any specialised […] Read more
Power currents (a. c.) can be measured simply by means of a clamp meter which acts as a current transformer. The instrument tongs are clipped round a single insulated conductor – the circuit is not interrupted. The value of current is obtained from the magnetic flux strength around the conductor and is usually displayed on […] Read more
The cooling system runs on the following standard layout: The central freshwater cooling system with single-stage scavenges aircooler and a separate HT circuit. As freshwater is the standard cooling medium of the scavenge air cooler(s), this involves using a central freshwater cooling system. The central freshwater cooling system comprises “low-temperature” (LT) and “high-temperature” (HT) circuits. […] Read more
Diesel electric propulsion and station keeping facilities are also used in vessels for operations in more shallow waters, such as dredgers and construction vessels, wind mill installation vessels, etc. Maneuvering and fuel economy with Diesel Electric Propulsion on Dredgers Accurate maneuverability with improved fuel economy, in combination with a need to move working place frequently […] Read more
The concept of electric propulsion is not new, the idea originated more than 100 years ago. However, with the possibility to control electrical motors with variable speed in a large power range with compact, reliable and costcompetitive solutions, the use of electrical propulsion has emerged in new application areas during the 80’s and 90’s.Electric propulsion […] Read more
