Custom Search
Over 10000 Pages Indexed
Your Host
Click here to read about RF CafeKirt
Blattenberger

... single-
handedly
redefining
what an
engineering website
should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5CCG (5th MOB):
My USAF radar shop

Hobby & Fun

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse
riding business website -
lots of info

•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe©

RF Cafe E-Mail

Electrician's Mate 3 - Navy Training Courses
NAVPERS 10548

Here is the "Electrician's Mate 3 - Navy Training Courses" (NAVPERS 10548) in its entirety (or will be eventually). It should provide one of the Internet's best resources for people seeking a basic electricity course - complete with examples worked out. See copyright. See Table of Contents.

 

U.S. GOVERNMENT PRINTING OFFICE; 1949


Electrician's Mate 3 - Basic Navy Training Courses - Chapter 16 picture

CHAPTER 16
BLUEPRINT READING AND SKETCHING

INTRODUCTION


Electrical wiring drawings or blueprints are maps which show you' the location and circuit connections of every piece of electrical equipment aboard ship. Blueprints properly used are an invaluable aid "trouble shooting", in other words, in isolating faults in an electrical circuit. This is undoubtedly the most important work of the naval electrician. You should therefore study the training course Use of Blueprints (NavPers 10621) to get a basic understanding of how blueprints are made and used. Then read tills chapter and you will know all the information that goes into Navy wiring blueprints and how to use it.

Mechanical drawing in the form of sketching frequently is used by the electrician in the event some electrical part is to be constructed in one of the ship's shops. A correctly made drawing will give a complete pictorial description of the part and therefore aid greatly in its construction. For this reason a brief review of what you learned in Use of Blueprints, and a few suggestions as to the layout of simple mechanical drawings, are included in this chapter.

 

PRODUCTION, CARE, AND FILING OF BLUEPRINTS


Blueprints are made from drawings in much the same manner that photographs are made from negatives. The negative for the blueprint is known as a TRACING. It is made by placing a sheet of special white, semi-transparent paper on cloth over the working drawing. Everything on the drawing is traced on the tracing cloth with black waterproof ink or a special black pencil. Some drawings are made directly on the tracing material in pencil, then traced with ink or the special black pencil. This short cut saves time and material and is satisfactory for most jobs.

To produce a blueprint the tracing is placed on a pane of clear glass mounted in a special frame. The tracing is covered with a sheet of chemically coated, light-sensitive blueprint paper. A padded back is secured behind the blueprint paper to keep the two sheets together. The front of the frame is then exposed to a strong light, which projects through the tracing onto the coated side of the blueprint paper.

After proper amount of exposure, the print is removed and washed in clear water to remove the unexposed chemical. The exposed portions of the print paper turn a deep blue during the washing. The lines will be white.

Blueprints are not always blue. They may be white, brown, black, gray, or other colors. The difference lies in the kinds of light-sensitive chemical on the paper, and in the development processes required for that chemical. But the process of making the print is the same - you project a light through the tracing onto the light-sensitive paper.

Blueprints are valuable permanent records and if properly cared for can be used many times. Listed below are a few simple rules for getting the best results from your blueprints.

KEEP them OUT OF STRONG SUNLIGHT, as they may fade.

Do NOT ALLOW them TO GET WET or grease smudged.

Do not pencil or crayon notations without proper authority. If you should get instructions TO MARK A BLUEPRINT, USE A YELLOW PENCIL. Black pencil marks are hard to see on a colored background.

Frequently used blueprints should be glued to a sheet of cardboard. Cover the face with a coating of clear shellac.  

FILING OF BLUEPRINTS


Blueprints are filed in the log room. The bulk of the electrical equipment aboard ship is provided by the Bureau of Ships and is shown on Bureau of Ships drawings. The Bureau of Ships system of designating and filing blueprints is desc6bed in the next few paragraphs. Turret and mount electrical installations are furnished by the Bureau of Ordnance and are shown on BuOrd drawings. The system of designating and filing BuOrd drawings is described following the BuShips system.
For BuShips drawings, all filing will be separated into letter groups. The prints an electrician will work with will be filed in the "S" group, covering Ship Materials. There are 94 separate divisions in the "S" group. A power distribution blueprint would be in group S-62, a lighting distribution print would be in group S-64. To locate the print you desire refer to the Na'l1J Filing A1anual to determine the division of the "S" group your circuit would be classified under and then look in the files for that division of the group.

Each print of a circuit or piece of equipment installed by a Navy yard will have an index, group, and file number on it.  Figure 148 shows a typical index group and file marking of a BuShips blueprint. The letters on the left denote the type of ship and the number of the ship in that class.
 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 148. - A blueprint index group and file number.

 

Figure 148. - A blueprint index group and file number.


In the center of the box is the circuit classification. The right hand numbers are the file numbers of the group indicated at center.

The index group and file markings of figure 148 indicate that this blueprint is from the heavy cruiser Wichita, it is a lighting distribution print, and it is to be filed a2 #25 in the S-64 group of files.

Bureau of Ordnance electrical drawings cover the electrical equipment and' wiring inside a turret or mount and are identified primarily by the serial number of the drawing. The drawing title also tells the mount or turret the equipment is part of, so to find the drawing for a piece of electrical equipment in a mount or turret, you must know the BuOrd designation for that mount or turret. You find this out from the Gunner's Mate, who can also provide you with the ordnance drawings, which are kept in the gunnery officer's office.

 

FUNDAMENTALS OF DRAFTING


Before you can thoroughly understand a blueprint and be able to sketch a drawing of your own, you must first know the types of lines used. Figure 149 illustrates the different lines.

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 149. - Types of lines in making drawings.

 

Figure 149. - Types of lines in making drawings.


The VISIBLE OBJECT lines represents visible edges, the outline of the object. If a surface is hidden from sight but needs to be shown in some manner, use an INVISIBLE OBJECT line. This line will show the location and extent of the hidden surface, and by rendering it broken, will- indicate that the surface represented is not from this view. Visible and invisible object lines are used in figure 150.

Whenever the object drawn is symmetrical about a common center, such as a shaft, a hole drilled in a casting, or any other circular object (that is just alike on both sides of the center) a CENTER LINE is used to indicate the axis of the hole or shaft. It is made of alternate dashes and single dots. Center lines should be drawn lightly. If a hole in an object is to be indicated, horizontal and vertical center lines both should be shown.

DIMENSION LINES are light lines having arrowheads at their ends. They are used to show the dimensions of the object. EXTENSION LINES are extensions of object lines. They indicate the limits of a dimension. The OBJECT LINES of a drawing, full or broken, always are heavier than the center, extension and dimension lines. Object lines are described as being number 1 lines in weight and all others number 2 in weight. The use of these lines is illustrated in figure 151.

 

SYMBOLS


When a draftsman makes an electrical wiring diagram, he uses electrical abbreviations or symbols instead of drawing each piece of electrical equipment in detail.- Unfortunately an identical piece of equipment may be represented by an entirely different symbol by different draftsmen. Therefore, a single set of standard symbols are difficult to prepare, but listed here are a few of the more common ones.

Actually there are two complete lists of symbols - ELEMENTARY and SCHEMATIC. The ELEMENTARY SYMBOLS, shown in figure 150, are used on wiring diagrams that SHOW each conductor and all the CONNECTIONS in the circuit. These symbols are more detailed than the schematic symbols. SCHEMATIC SYMBOLS, some of which are shown in figure 154, are used to SHOW the LOCATION and general layout of the circuit. The types of drawings in which the different types of symbols are used are discussed in the later paragraphs on WIRING DRAWINGS.

Notice that no elementary symbols specify watertightness while schematic symbols do. On the schematic list the symbols showing watertightness have a double line. W. T. is the abbreviation for watertight. N. W. T. indicates that the piece of equipment represented is not watertight.
 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 150. - Electrical symbols.

 

Figure 150. - Electrical symbols.

 

ORTHOGRAPHICS


A drawing is a plan, sometimes a specification. Drawing' is a means of expression, and consequently is a form of language. It is far better to give a machinist's mate a drawing of a sleeve bearing that you wish to have made than to give him an oral description of the bearing.

The clearest method of representing an object is by showing it in ORTHOGRAPHIC views. Orthographic comes from the word "ortho," which means at right angles to. An orthographic view, therefore, is any drawing that shows true size and shape of one surface of an object when that surface is at right angles or perpendicular to your line of vision.
 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 151. - Views of a block.

 

Figure 151. - Views of a block.


You may make as many orthographic views as the object has sides. If the object drawn has an irregular shape, that is all its sides are different then the drawing will contain a view for each side. Seldom are more than two or three views necessary to give a complete picture of an object. In all cases a correctly made orthographic drawing contains as many views as necessary to give a complete description of an object. Figure 151 is an orthographic drawing of a block. Six orthographic views of this object could be drawn. Careful inspection of the object will reveal that the top and bottom are identical, and that there is no difference between the front and black side, or right and left ends. Therefore, as shown in figure 151, only three views are necessary.
 

HOW TO MAKE A DRAWING


Following is a list of the general. steps to help you in sketching an orthographic drawing. Practice on simple objects first, then try the more difficult.

   Study the object and decide the combination of views that will give the best description.

   Block in outline views, in proper arrangement, with light construction lines.

   Build up the detail of each view, such as representing all invisible edges with broken lines.

   Give each view its proper name and dimensions.

   Check drawing for any possible errors.

   Darken all object lines and erase construction lines which have no further purpose
   to the drawing.

To satisfy step 1, bear in mind that an orthographic drawing needs only as many views as necessary to give a complete picture of an object. All orthographic drawings should have the views presented in their proper relation. That is, don't put end views on top, and bottom views on top. Referring to figure 151, you can see that all horizontal measurements on both the front and top views are equal. This is the reason they are drawn IN LINE with each other. The vertical measurements of the front and' end views sometimes are different and the arrangement of the views is not always the same, but the same RELATIVE POSITION of the views in regard to each other always IS THE SAME.

The scale of a drawing refers to the size of the drawing in relation to actual size of the object. Thus when a drawing is made on a scale of 1 inch equals 1 foot, the size of the drawing is one twelfth of the size of the object drawn. Before beginning any drawing determine the scale to be used and make a note of it on the drawing.

 

ISOMETRICS


Often it is desirable to give a "picture drawing" in conjunction with an orthographic sketch so one may gain an idea of the general shape and size of an object. This type of drawing is called PERSPECTIVE.

A perspective drawing is to show an object exactly as it appears to your eye. A perspective drawing would show the same outline that would appear in a photograph.

Your eye as well as the photograph and perspective drawing tell you things that aren't exactly true. Just recall the last time you looked down a straight stretch of railroad track. Your eyes told you that the tracks came together at a distant point. You knew the tracks were parallel so you didn't believe your eyes. The camera records this deception and since the perspective drawing gives exactly what is seen to the eye, it also registers a lie.

The isometric drawing is similar to the perspective, but all parallel edges are drawn truly parallel. All its lines representing horizontal and vertical lines on an object have true length. Vertical lines are shown in a vertical position, but lines representing horizontal edges are drawn at an angle of 30° with the true horizontal. Vertical lines and lines representing horizontals are known as isometric lines. The picture at the top of figure 151 is an isometric drawing.

Isometrics cannot be used alone for complicated parts or structures, but may be used as an aid in clarifying the accurate orthographic drawings. Remember that no lines except the isometric lines of an isometric drawing can be relied upon for true measurements.

 

SHIP COMPARTMENTATION AND EQUIPMENT MARKING


The different parts of a ship are named so you can talk about a certain part enabling another person to know exactly what you are talking about.

Knowing how the different decks are numbered, how the compartments are labeled, and how electrical equipment is numbered will enable you to work more readily from a wiring blueprint.

There are two types of decks, COMPLETE DECKS and PARTIAL DECKS. A complete deck is a deck running the full length of the ship and a partial deck is a deck running only part of the length of the ship. Decks are named and numbered according to their location above or below the main deck. The MAIN DECK is the topmost complete deck.

A partial deck that is one deck level above the main deck at the bow is called the FORECASTLE DECK; at the stern, POOP DECK; amidships, UPPER DECK. A partial deck above the main, upper, forecastle, or poop deck and not extending to the side of the ship is called a SUPERSTRUCTURE DECK.

A complete deck below the main deck is called the SECOND DECK. Where there are two or more complete decks below the main deck, they are called .the SECOND DECK, THIRD DECK, FOURTH DECK, etc. A partial deck between two full decks where vertical height permits is called a HALF DECK. A partial deck below the lowest complete deck is called a PLATFORM. Where there are two or more partial decks below the lowest complete deck, the one immediately below the lowest complete deck is called the FIRST PLATFORM, the next is called the SECOND PLATFORM, and so on. The space below the lowest platform is referred to as the HOLD. The deck at the bottom of the hold is the HOLD DECK.

Decks are numbered using the main deck as a reference level. The main deck is number 1 deck level. The next deck below the main deck,' regardless of its name, is number 2 deck level; the second deck below the main deck is number 3 deck level, and so on down to the hold deck.

The first deck above the main deck is 01 deck level, the second deck above the main deck is 02 deck level and so on to the topmost deck of the ship.

A half deck takes the number of the deck directly below it. A letter "H" precedes this number to denote a half deck. A half deck located between the main and second decks would be numbered "H2".

As an example of how decks are numbered, consider a ship having a superstructure deck, an upper deck, a main, second, and third deck, a first and second platform, and a hold deck. In addition to these decks there is a half deck between the second and third decks. These decks will be numbered as follows:
Superstructure deck ...... 02 Third deck ................ 3
Upper deck .................... 01 First platform ........... 4
Main deck ...................... 1 Second platform ...... 5
Second deck .................. 2 Hold deck ................. 6
Half deck ....................... H3    

 

COMPARTMENTS


Transverse bulkheads across the ship cut naval vessels into 3 or 4 main sections. These sections are labeled A, B, 0, and D, from fore to aft. In a three-section ship, SECTION A extends from the bow to the first transverse bulkhead of the engineering section. SECTION B includes the space from first bulkhead to the after bulkhead of the engineering section. SECTION C comprises the remaining section aft.

In a four-section ship, the machinery or engineering space is divided into two parts, sections Band 0, with SECTION D comprising the remaining spaces aft. While the ship is considered as having only three or four main sections, that does not mean that there are only two or three transverse bulkheads. There are, many others, all adding to the structure of the vessel and contributing to its compartmentation and watertight integrity.

Compartments aboard ship are given letters and numbers denoting the location and use of the compartment. The following compartment marking is an example:

 

 A-201-L

A 2 01 L
Section of
 Ship
Deck Level Position of Compartment in the Section Use of Compartment

Taking the letters and numbers from left to right the first letter indicates the section of the ship the compartment is located in. The first number tells us the deck level. The two numbers following the deck level tell us whether the compartment is located on the port or starboard side of the ship and also give us the position of the compartment fore and aft in the section.

Port side compartments have even numbers, starboard compartments odd numbers. The first compartment forward on the port side of a general section in the ship is given the number 02, the next compartment aft of it on the port side 04, etc. All numbers in each section begin at the forward end of that section.

The letter at the right gives the use of the compartment. The list below is an explanation of the code -

   A       Storerooms.
   B       Gun and torpedo battery compartments.
   C       Ship control and fire control compartments.
   E       Machinery compartments.
   F       Fuel compartments.
   LUB   Lubricating oil storage compartments.
   GAS   Gasoline compartments.
   L        Living compartments.
   M       Ammunition storage compartments.
   T       Trunks and hatches.
   V       Void compartments.
   W      Water compartments.

All compartments and spaces that are bounded completely by watertight, oiltight, airtight, or fumetight structures have their own individual markings. Where a watertight compartment located below the, weather deck is divided into two or more airtight or fumetight spaces by air tight or fume tight bulkheads, the appropriate number is assigned the watertight compartment and each airtight or fumetight subdivision within the compartment is designated by the addition of a suffix to this number. Thus if watertight compartment

A-312-L contains fumetight or airtight longitudinal (fore and aft) bulkheads, the space to starboard of this bulkhead is designated as A-312-1L and the space to port as A-312-2L.

A half deck compartment has the letter H directly before the deck level.
Here are some examples:

 

B-301-E

B 3 01 E
Amidships Section Third deck Forward compartment
Starboard side
Machinery compartment


B-0102-E

B 01 02 C
Amidships Section One deck above the main deck Forward compartment
Port side
Ship control or fire control compartment

 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 152. - Deck and comportment numbering system.

 

Figure 152. - Deck and comportment numbering system.


Compartments such as pump rooms, auxiliary machinery rooms, engine and fire rooms generally extend upwards through two or more decks. These are numbered from forward to aft in order. Their numbers are prefixed by the section letter. For example, a pump room forward might extend two decks, in which case its number would be A-I; the next compartment, extending two or more decks, would be the fire room which would be B-2, followed by the engine room, B-3. Should there be a similar place aft, it might be called C-4. The numbers follow in order, the letters changing according to the section in which the compartment is located. The numbering system for decks and compartments is illustrated in figure 152.
 

MACHINERY MARKINGS


Every piece of electrical equipment is given three numbers as -


3-46-1

Deck level Frame Port or Starboard Position
3 46 1

 
Here again as in the case of compartment marking, a piece of equipment located on a half deck has a letter H prefixed to the number of the deck level directly below the half deck.

Equipment on the center line does not have the third letter as it is on neither port or starboard side.
If the equipment is between frames, it takes the number of the frame forward.
 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 153. - Method of numbering power panels.

 

Figure 153. - Method of numbering power panels.


Should there be two or more pieces of equipment located on the same deck, same frame, same side of ship, then the last number denotes position in regards to the center line. 305

Consider the case as in figure 153 when we have three panels all located on the second deck, frame 81, port side. The panel nearest the center line has the smallest even number, the next panel outboard has the next higher even number, and so on outboard.

Figure 153 is an example of how equipment is marked at various locations. Note that if a piece of equipment straddles a frame it takes the number of the preceding frame. (See panel (2-72-2)).

 

TURRET AND MOUNT MACHINERY MARKINGS


Every turret and mount is full of mechanical installations which do special jobs such as elevating the guns, hoisting powder or projectiles up to the guns, etc. These installations are furnished by the Bureau of Ordnance and each installation is called an ORDNANCE ASSEMBLY. Each assembly is designated by a name indicating the job it does, and a "Mark" and "Mod" number indicating a particular design of such an assembly. Thus in the 5-inch single mounts on carriers of the MIDWAY class (5-inch Gun Mount Mark 39), these are some of the Ordnance Assemblies you will find: Elevating Gear Mark 15 Mod 0, Projectile Hoist Mark 6 Mod 0, Power Hoist Mark 6 Mod 0.

The motor switches, and other electrical parts associated with each Ordnance Assembly are considered parts of that assembly. Each of these electrical parts has a name plate which tells you what Ordnance Assembly it is part of.

A complete set of drawings for every Ordnance Assembly is furnished by the Bureau of Ordnance to each ship and is kept in the Gunnery Officer's Office. These drawings show where each part of the assembly is located and how it is constructed. So if you want to know where a particular piece of electrical equipment in a mount or turret is located, or how it is constructed, first find out what Ordnance Assembly it is part of. Then ask the Gunnery Officer or Chief Gunner's Mate for the folder of drawings on that assembly. Looking through the drawings in this folder you will find drawings which show the location and construction of the electrical part you are interested in.

 

ELEMENTARY WIRING DRAWINGS


All shipboard wiring blueprints fall under the three general headings of ELEMENTARY wiring drawings, ISOMETRIC wiring drawings, and wiring DECK PLANS.

The ELEMENTARY wiring drawing is, as the name implies, as simple and detailed as possible. It shows each individual conductor in the circuit and every connection made. It mayor may not show the connection boxes themselves. In all Interior Communication (IC) circuits the lugs in each connection box are stamped with the proper lead markings. The elementary wiring diagram shows these lead markings alongside each lead of the circuit.

In the case of an elementary wiring drawing for a controller the drawing often shows the relative position of the various components of the controller. Most elementaries, however, show nothing of the fixtures or cable runs. Because of this, elementaries are not drawn to scale. Elementary drawings use the elementary type of symbols. An elementary drawing would be used to check proper connections in a circuit or to make the initial hook-up. Each elementary wiring blueprint contains one circuit only.

 

ISOMETRIC WIRING DRAWINGS


Each electrical system has its own ISOMETRIC wiring drawing. If the individual system is not too large, it will be covered by one blueprint. There will be a separate isometric wiring diagram for each IC circuit.

In isometric drawings the decks are arranged in tiers, starting at the bottom with the hold and successively arranged to the bridges and superstructure. Section and divisional bulkheads are shown as well as the bulkheads that divide the deck into the main compartments. The center line is marked with frame numbers every five or ten frames. The outer edge of each deck is drawn with the general outline of the shape of the ship.

All athwartship lines are shown at an angle of 60° to the center line, and the location of compartments as shown by the blueprint gives an accurate idea of the deck arrangement, although not in detail. The purpose of distorting the athwartship lines is to permit the continuous representation of cables passing between decks. Cables running from one deck to another are drawn as light lines at right angles to the center line.

The exact location of fixtures and cable runs cannot be satisfactorily arrived at by use of an isometric wiring blueprint because the locations shown are only approximate. The symbol numbers of the fixtures in the circuit are given and also the cable numbers and sizes. This aids the electrician in associating each circuit with its elementary wiring drawing. An isometric wiring diagram for a turret is shown in figure 154. What this diagram means is illustrated in figure 155.
 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 154. - Isometric wiring diagram for 8-inch turret illumination system.

 

Figure 154. - Isometric wiring diagram for 8-inch turret illumination system.

 

RF Cafe - Electrician's Mate 3 - Navy Training Courses, NAVPERS10548 - Figure 155. - The turret illumination system indicated by the wiring diagram in figure 154.

 

Figure 155. - The turret illumination system indicated by the wiring diagram in figure 154.


Elementary and isometric presentations of a circuit often are on the same blueprint. Isometric wiring drawings never are drawn to anyone set scale. The isometric wiring drawing uses schematic symbols.

A cable, regardless of number of conductors, is represented on an isometric wiring diagram by a single line, and no attempt is made to show the proper connections in connection boxes or at fixtures. An isometric type of drawing thus shows at a glance a rough picture of the entire circuit's layout. Isometric wiring diagrams of lighting and power circuits usually are used to indicate only the main supply cables, feeders, and their associated equipment.

 

WIRING DECK PLANS


The WIRING DECK PLAN is a blueprint used chiefly in construction. It enables the Navy Yard electrician to layout his work for a number of cables without referring to each individual isometric wiring drawing. Wiring deck plans do not distort the athwartship members, but represent a true plan.
LIGHTING and POWER wiring deck plans are the actual installation diagrams for the particular deck illustrated. For these systems, the print includes a bill of material listing all material and equipment required to complete the installation on the deck concerned. Equipment and materials, except cable, are assigned symbol numbers and are so indicated on the drawing and in the bill of materials.

Lighting and power circuits, in alternating current work, have indicated at each single-phase fixture, fitting, or appliance the phase to which it is to be connected, such as: AB PHASE, BC PHASE, or CA PHASE. Equipment not so indicated is threephase.

INTERIOR COMMUNICATION and similar type wiring deck plans are informative plans only, and are merely a composite of all like systems. For these systems, a list of symbols replaces the bill of materials. Symbols and symbol numbers are shown on the plan, but unlike the isometric the section leads of the cables are not indicated.
Wiring deck plans always are drawn to the scale of 1/4 inch equals 1 inch. This drawing, therefore, shows an accurate location of all fixtures. The deck plan shows from 150 to 200 feet of deck space on one deck only. A ship 500 feet long at the main deck would require three wiring deck plan blueprints for each system on the main deck. This type of blueprint, like the isometric, uses schematic symbols.

On a small ship a wiring deck plan may cover more than one electrical system. One wiring deck plan may cover the power, lighting, and IC systems.
 

TROUBLE SHOOTING BY USE OF BLUEPRINTS


The real value of any knowledge is determined by whether or not a man can use what he knows in practical application. The proper use of blueprints in isolating electrical troubles pays dividends in many ways. It eliminates much of the guesswork in locating trouble in a faulty electrical circuit. Blueprints will save many man-hours spent "sight traveling" a cable along the overhead, down the bulkhead, and through the decks, trying to arrive at its termination at some questionable point.

As a simple example-in isolating trouble in a circuit, assume an electrician is taking insulation tests on the IC circuit fed from the IC switchboard. His "Megger" registers a zero ground on the general alarm circuit. Since he is not familiar with the location of the various components of this circuit he heads for the log room to draw out the isometric wiring diagrams and elementary wiring diagram of the "G" circuit. At this time he asks permission to secure the general alarm system while he locates the fault.

By looking at the isometric of the "G" circuit he locates all the connection boxes. From here on he starts a progressive bread-down of the circuit. The logical steps would be:

   1. In the first connection box after leaving the switchboard, break all connections.
   2. Read each section of the circuit emanating from the box with the megger.
   3. After locating the section grounded, remake all connections in the box, close the box,
       and move along the grounded cable to the next connection box or fixture.
   4. Repeat steps 2 and 3 along the line until the ground is isolated to one individual
       fixture or section of cable.

When the work is completed care should be taken that all covers are properly replaced and secured and the blueprint is again stored in its proper position in the files.
 

 

Chapter 16 Quiz

(click here)

A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel