Marine solutions

Boiler Easing Gear   Why is it fitted? As per SOLAS chapter II-1 regulation 32 “Every steam boiler and every un-fired steam generator shall be provided with not less than 2 safety valves of adequate capacity. However, having regard to the output or any other features of any boiler or un-fired steam generator, the administration may permit only one safety valve to be fitted if it is satisfied that adequate protection against over pressure is thereby provided”. Generally on boilers used on ship two safety valves are fitted. These safety valves are o/hauled in dry-dock and set to open at 3% more than the max allowable pressure, in presence of a surveyor. In case of economiser safety valves the valves are set by the chief engineer at sea and the surveyor is informed. Safety valves are provided to prevent over pressurisation of the boiler, which would cause it to explode and can be harmful and fatal for personnel. Easing gear is fitted basically to allow for

A  star delta starter  is the most commonly used method for the starting of a  3 phase induction motor . In star delta starting an  induction motor  is connected in through a  star connection throughout the starting period. Then once the motor reaches the required speed, the motor is connected in through a  delta connection . Here, the motor starts with a star connected stator winding, and as when motor reached about 80% of its full load speed, it begins to run in delta connected stator winding. Star delta starter is a type of reduced voltage starter. We use it to reduce starting current without using any external device or apparatus. The starter mainly consists of a TPDP switch which stands for Tripple Pole Double Throw switch. This switch changes stator winding from star to delta. During starting condition stator winding is connected in the form of a star. Now we shall see how a star delta starter reduces the starting current of a three-phase induction motor . For that let u

An electrical motor is such an electromechanical device which converts electrical energy into a mechanical energy. In case of three phase AC operation, most widely used motor is Three phase induction motor as this type of motor does not require any starting device or we can say they are self-starting induction motors. For better understanding, the principle of three phase induction motor , the essential constructional feature of this motor must be known to us. This Motor consists of two major parts: Stator of Three Phase Induction Motor Stator of three phase induction motor is made up of numbers of slots to construct a 3 phase winding circuit which we connect with 3 phase AC source. We arrange the three-phase winding in such a manner in the slots that they produce one rotating magnetic field when we switch on the three-phase AC supply source. Rotor of Three Phase Induction Motor Rotor of three phase induction motor consists of a cylindrical laminated core with paralle

The working principle of alternator is very simple. It is just like basic principle of DC generator . It also depends upon Faraday’s law of electromagnetic induction which says the current is induced in the conductor inside a magnetic field when there is a relative motion between that conductor and the magnetic field. For understanding working of alternator let us think about a single rectangular turn placed in between two opposite magnetic poles as shown above. Say this single turn loop ABCD can rotate against axis a-b. Suppose this loop starts rotating clockwise. After 90 o rotation the side AB or conductor AB of the loop comes in front of S-pole and conductor CD comes in front of N-pole. At this position the tangential motion of the conductor AB is just perpendicular to the magnetic flux lines from N to S pole. Hence, the rate of flux cutting by the conductor AB is maximum here and for that flux cutting there will be an induced current in the conductor AB and the direction

Alternator is really an AC generator. In alternator , an EMF is induced in the stator (stationary wire) with the influence of rotating magnetic field (rotor) due to Faraday’s law of induction . Due to the synchronous speed of rotation of field poles, it is also known as synchronous generator . Here, we can discuss about parallel operation of alternator . When the AC power systems are interconnected for efficiency, the alternators should also have to be connected in parallel. There will be more than two alternators connected in parallel in generating stations. Condition for Parallel Operation of Alternator There are some conditions to be satisfied for parallel operation of the alternator . Before entering into that, we should understand some terms which are as follows. The process of connecting two alternators or an  alternator and an infinite bus bar system in parallel is known as synchronizing. Running machine is the machine which carries the load. Incoming machine is the al

Construction wise, an alternator consists of field poles placed on the rotating fixture of the machine i.e. rotor as shown in the figure above. The rotor rotates in the stator. The field poles get projected on the rotor body. The armature conductors are housed on the stator. An alternating three-phase voltage represented by aa’, bb’, cc’ is induced in the armature conductors thus resulting in the generation of three-phase electrical power . All modern electrical power generating stations use this technology for generation of three-phase power, and as a result, the alternator or synchronous generator has become a subject of great importance and interest for power engineers. An alternator is basically a type of AC generator which also known as synchronous generator. The field poles are made to rotate at synchronous speed N s = 120 f/P for effective power generation . Where, f signifies the alternating current frequency and the P represents the number of poles. In most prac