Electrical Exam Flashcards
What are the two basic reasons for having more than one type of blueprint?
A) To prevent a print from being too large for effective use.
B) To provide more legibility by not jamming the information too close together.
What are the four basic types of electrical blueprints?
Elementary, isometric, wiring plans, and schematics
why must we have standard symbols and reference designations for use in electrical and eletronic blueprints?
So that all blueprints regardless of the developing activity, are easily understood by all users
How are the identifying location numbers for electrical units assigned aboard ship?
Lowest to highest, forward to aft, starboard to port.
The letters ___,___, and ___ are used to identify the phases in a three phase electrical circuit.
A,B, and C
Power and lightning cables and circuits are classified into ___,__ and ___ groups according to their importance and are identified respectively by the following colored cabled tags: ___,___ and ___ .
Vital, Semivital, and Nonvital;
Red, Yellow, and Gray
How do the identifying numbers differ for the feeders emanating from the forward and after switchoards?
Forward switchboard feeders have odd numbers for identification; after switchboard feeders have even numbers for identification
Why was it found necessary to develop a a new electrical equipment designation system which would be an improvement over the 1949 system?
Increasing numbers of electrical equipment aboard ships made the 1949 system cumbersome and ambiguous in identification data
The ____ wiring drawing shows each individual conductor in the circuit and every connection made.
Elementary
The ____ diagram’s purpose is to show connections for operation of the electrical or electronic circuit.
Schematic
The ___ ___ ___ is a blueprint used chiefly in construction work.
Wiring deck plan
Shipboard drawings may be classified under which four general headings?
Elementary wiring diagrams, Schematic wiring diagrams, Isometric wiring diagrams, Wiring deck plans
What are electrical drawings called which show the elecric wiring for a building or other structure?
Electrical Layouts
What is electric current?
Electric current is a flow of electrons along a conductor
Why do some metals make good conductors of electric current?
Metallic atoms give up their electrons to other atoms very easily
Why do some materials make make good insulators?
They require great force before electrons can be detached from them
What are the components of the simplest form?
A power source , the load, and the conductors running from the source to the load and back to the source.
In what direction does electric current flow in a circuit?
From negative terminal to the positive.
Name three basic types of circuits
Series ciruits, Parallel circuits, and Series-parallel circuits
What is the unit of measurement for the rate of current flow in a circuit?
The ampere
What is the unit of measurement for resistance?
The ohm
What is the unit of measurement for electromotive force (emf) ?
The volt
What is the unit of measurement for electrical power?
The watt
How does alternating current (a.c) differ from direct current (d.c) ?
Direct current flows in one direction around a cirucuit; Alternating current flows in one direction and then reverses itself and flows in the other
How is electric current induced by a magneticfield?
The conductor cuts through the magnetic field?