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?
What electrical device is used to store electric energy in a static field?
A capacitor
What happens when a heavy electric current flows through a small conductor?
The conductor becomes heated
How is a motor different from a generator?
A generator is designed to convert mechanical energy into eletrical enegery, while a motor is designed to convert electrical energy into mechanical energy.
Why is alternating current better than direct current for use where power is to be transferred over long distances?
Alternating current is better than direct current for use where power is to be transferred over long distances , because transformers can be used in AC systems to change the ratio between voltage and current , and with a high voltage and low current in the circuit , smaller wires can be used and there is less heat loss.
Name two types of advanced base AC distribution systems
The two types of AC systems are three-wire and four-wire
What type of distribution system would you find with a y-connected alternator?
A four-wire distribution system would be found with a y-connected alternator
What are drawings called which show actual as-built conditions when slight revisions or additions have been made to meet local conditions?
Drawings showing actual as-built conditions are called record drawings
What is the place where the wires of an electrical circuit enter a building called?
The place where the wires of an electrical circuit enter a building is called a service entrance
When two of the wires in an interior wiring circuit carry 230 volts and a third wire is neutral, what advantage is gained in terms of operating electrical devices?
Electrical devices rated at either 230 volts or 115 volts may be operated
Why is the neutral wire not broken by a switch or fuse at the service switch?
Since the neutral wire is grounded , it is no longer a live wire , and there is no need to break its circuit at the service switch
what does the first letter on the tag on a cable for wiring tell about the cable?
The first letter tells how many conductors are in the cable
What is the channel method of illustrating cable diagrams?
It is a method whereby a heavy line is used to illustrate all of the cable in a run with the individual cables fanned out and identified at terminating points
Which of two types of cable are mainly used for interior wiring of buildings, and what trade names are they called by?
Non-metallic sheathed cable, called romex and armorded cable BX, are the main types of wiring cable used
What device is used to increase the distance range of a somple telephone circuit?
A transformer , or inductrion coil , is used to increase the distance range of simple telephone circuit.
What are five pieces of telephone equipment found in practically every telephone switchboard?
Cords, Plugs, jacks, signal, keys
What is one distributing frame in a switchboard office called and what is an additional frame called?
One distributing frame in a switchboard office is called an mdf or main distribution frame and an additional frame is called an IDF or intermediate distributing frame
Name three types of protective devices placed in lines, both at the substation and the switchboard office
The three types of protective devices placed in lines, both at the substation and the switchboard office, are heat coils, fuses, and lightning arresters
In order to show the true-sized shape of an inclined surface on a machine drawing, one should draw a(n)…
A.) Elevation
B.) Oblique
C.) Auxilary View
D.) Typical Orthographic View
C.) Auxilary View
The space curve on which the screw thread is based is the…
A.) Spiral
B.) Cycloid
C.) Involute
D.) Cylindrical Helix
D.) Cylindrical Helix
For mechanical representation , isomtetric drawings are usually preferred to perpective drawings because isometric drawings…
A.) Are three dimensions
B.) Can be easily drawn to scale
C.) Closely approximate the view obtained by the human eye
D.) Can be laid out at any convenient angle
B.) Can be easily drawn to scale
The term used to describe the developement of a cylinder is ____ development.
A.) Radial
B.) Cylinder Line
C.) Parallel Line
D.) Prismatic
C.) Parallel Line
A steel shaft whose nominal diameter is 1.375in.(tolerance .005) willi have at maximum diameter a clearance of .002 in a hole whose minimum diameter is..
A.) 1.382
B.) 1.380
C.) 1.378
D.) 1.376
A.) 1.382
The term addendum in a machine drawing applies to the design of a ..
A.) Spur Gear
B.) Plate Cam
C.) Cylindrical Cam
D.) Ball Bearing
A. Spur Gear
In a gear train, the change of motion from one at a particular direction to another at right angles may be achieved by use of ..
A.) Bevel Gears
B.) A Rack and pinion
C.) Spur Gears
D.) All of the above
A. Bevel Gears
To drill a 1/2” Diameter hole in a series of duplicate machine parts, use is made of a ..
A.) Horizontal Boring Machine
B.) Jig
C.) Vertical Mill
D.) Matrix
A.) Horizontal Boring Machine
A section through a right cone making the same angle with axis as the elements do, will describe a(n)..
A.) Trapezoid
B.) Ellipse
C.) Parabola
D.) Triangle
C. Parabola
On a map drawn to a scale of 1” = 250 miles. The actualt length of the distance between two cities 3200 miles apart will be _____ inches.
A.) 10.6
B.) 12.8
C.) 16.4
D.) None of the above
B.) 12.8
The constant pressure angle at the point of contact of the teeth of two mating involute spur gears is _____.
A.) 14 1/2
B.) 15 1/2
C.) 29 1/2
D.) 30 1/2
A.) 14 1/2
A right cone has an altitude of 4 1/2. The diameter of the base 2 1/2. The length of the arc for a radial development will be ____ inches.
A.) 6.14
B.) 6.33
C.) 7.07
D.) 7.22
C.) 7.07
The name of the form of development used for a transition piece is _____.
A.) Offset
B.) Radial Line
C.) Triangulation
D.) Parallel Line
C.) Triangulation
The motion of diagram for a cam whose rise is 1 1/2” should have a length of ..
A.) 1 1/2”
B.) 3”
C.) 4 1/2”
D.) The circumference of base circle
D. The Circumference of base circle
A plate cam imparts to a roller follower a type of motion which can be best described as ..
A.) Rotary
B.) Reciprocation
C.) Angular
D.) Spherical
B.) Reciprocation
(Reciprocating Motion is a motion in which the cam and the roller move with each other in the same up and down motion)
The drawing of a house that shows the rooms, walls, doors, etc. is properly called a(n)…
A.) Section
B.) Plan
C.) Top View
D.) Elevation
B. Plan
The most typical scale used in the drawing of frame dwellings is one(-) ______ equals one foot.
A.) Half Inch
B.) Sixteenth of an inch
C.) Thirty- second of an inch
D.) Quarter Inch
D.) Quarter Inch
The Shape of the unified thread is…
A) Flat at the crest and round at the root
B.) Flat at both the crest and root
C.) Round at both the crest and root
D.) Pointed at both crest and root
A. Flat at the crest and round at the root
To eliminate confusing hidden lines in a machine drawing…
A.) a sectional view should be drawn
B.) a back view should be drawn
C.) show section linking in the side view
D.) omit the hidden lines
A.) a sectional view should be drawn
In Order to make an oblique drawing, the…
A.) object is placed with one of its principal faces parallel to the plane of projection
B.) Side and top views are usually drawn at a 30 degree angle
C.) Side and top views are usually drawn at a 15 degree angle
D.) Side and top views are usually drawing with converging lines
A.) Object is placed with one of its principal faces parallel to the plane of projection
A black and white in drafting room language most likely means a(n)…
A.) Ink drawing on cloth
B.) Pencil drawing on paper
C.) Print with black background and white lines
D.) Print with black lines and white background
D.) Print with black lines and white background
The feature that , distinguishes a civil engineer’s scale from an architect’s scale is that the engineer’s scale …
A.) Is usually longer
B.) does not have inch divisions
C.) Is found on a slide rule
D.) Is made with decimal divisions
D.) Is made with decimal divisions
