Showing posts with label electric equipment. Show all posts
Showing posts with label electric equipment. Show all posts


English tests for electrical engineers with the answers

A list of the most common questions for electrical engineers (ETO) that are asked in crewing companies or when passing qualification testing. These questions and answers will also help you prepare for the CES test at a basic level.

English tests for electrical engineers with the answers


Ordering Directions and Standard Equipment

For ordering electric drive equipment for ship's deck machinery consult tables listing electric drives of various applications.

After determining the power rating of servo motors from the formula given in the catalogue select a power drive equipment with the nearest power rating and then make sure that the control properties of the drive indicated on the mechanical characteristics suit the operating conditions of the electric equipment set.

The order for delivery of an electric equipment set or a separate motor must contain the following information:
  • name of the machinery (gear), kind of the current and the ship's mains voltage;
  • type of the motor and its electrical characteristics as indicated in tables;
  • provision of a built-in disk brake and the operating conditions of the brake;
  • design version of the motor;
  • number of the free ends of the shaft (without a built-in brake); set number according to tables;
  • number and type of limit switches in the standard equipment; provision of a spares set;
  • provision of a Certificate issued by the Register.
For ordering separate electrical apparatuses use the data given in tables.

The order for delivery of a magnetic controller and a cam controller must contain the following information: application of the magnetic and cam controllers; class protection; rated current; number of startings per hour; type; operating duty; electric wear resistance level; control circuit voltage; voltage; settings of thermal protection relays.

An example of an order for an electric equipment set:
Electric equipment set for a mooring capstan, 380 V A. C. Motor MA 11 421-4/8 A, two-speed, power rating 7.0/5.6 kW, rotation speed 1400/650 rpm, 30/30 min duty.

Built-in brake type TNT 42, braking torque 12 daNm, 60 min duty. Design version-vertically mounted, flange type, without feet, M 302, for building into capstan head. Set No. 8 acc. to Table 15.
One set of spare parts per standard equipment set. With Certificate of the Register.

The spare parts set for the electrical equipment comprises parts and assemblies which can be used for the repairs to be carried out on the ship. The spares sets are packed in sturdy wooden cases adopted for long storage on the ship.

The spares set comprises the following parts and assemblies: braking disks for brakes — 1 set; brake coil — 1 set; brake spring — 1 set; moving and stationary contacts of all types — 1— 3 sets; springs for apparatuses of all types — 1 — 4 sets; apparatus coils — 1 per design version; fuses — 2 sets: rectifiers-—1 set; vitrified resistors — 1 per design version; cam assembly — 1 — 11 per design version.

The list of spare parts supplied with the given equipment is included in the set of technical documentation.

A-C Electric Equipment of Ship's Deck Machinery

Modern electric equipment of ship's deck machinery comprises electric motors and electric apparatuses of specially developed series and individual designs.

The fact that this machinery has to operate on weather decks predetermines special environmental conditions of the electric equipment: ambient temperatures ranging from —40 to +50° C, high humidity up to due fall with frequent cyclic variations, pitching and rolling, strong vibration, periodic splashing with sea water, high dynamic overloads and a large number of on-load startings.

The electric equipment of deck machinery meeting all specific requirements of marine service is noted for a high electrical strength and mechanical robustness. With regular maintenance and timely replacement of worn parts the service life of the electric equipment is as long as 15—20 years.

Utilized construction of the electric equipment, used in deck machinery makes it possible to provide for any operating conditions in the course of its service.

To improve its reliability and efficiency the electric equipment is being constantly developed through the use of new structural materials and new switching and control systems and through a detailed study and overall improvement of the interaction between the electric drives of the deck machinery and other ship's equipment.