Review

This lesson will familiarize RAC technicians with the most important factors and gives you some appreciation on RAC signs ,symbols and data.

RAC symbols are the language used to let you know how to read RAC work plans. The RAC symbol is used as shorthand and can provide you with all the needed information. The emphasis in this lesson is on analyzing and interpreting RAC symbols so that you will develop a “vocabulary” in Refrigeration and Airconditioning.

· Interpret technical drawings and plans

In electrical schematics, the symbols stand for various components in the circuit, and the lines stand for the wires connecting them. The intention of the overall schematic is to show how the circuit functions, not how it actually looks.

A wiring schematic shows the condition of a piece of equipment when there is no power being applied to the unit. For example, if a switch is depicted as being normally open (N/O) or normally closed (N/C), remember that the position of the switch is shown as it appears when there is no power applied to that circuit. If there is any deviation from this practice, there will be an explanatory note on the schematic.

Before you begin looking at electrical schematic diagrams, though, remember that there are always five basic components to any schematic:

1. A power supply,

2. A path for the power,

3. A load or component that operates from the power,

4. A switch or component that interrupts the power to the load,

5. A legend or key that explains what the various symbols and abbreviations used in the wiring diagram.

3- Types of Electrical Wiring Diagrams For Air Conditioning Systems

There are three basic types of wiring diagrams used in the HVAC/R industry today, which are:

1. The Ladder Diagram

It is the most common type of wiring Diagrams. It is called ladder because the symbols that are used to represent the components in the system have been placed on the rungs of a ladder. ladder diagrams will be referred to as “schematic” diagrams, or simply “schematics.”

2. The Line Diagram

It usually includes drawings that more closely resemble the components themselves, rather than symbols.

3. The installation diagram

This diagram is used primarily by the installing contractor. It normally shows only what the terminal board connections are, and very rarely will it include any internal wiring of the unit.

LADDER DIAGRAM

LINE DIAGRAM

INSTALLATION DIAGRAM

Free hand drawing: Sketching, Shading, and Outlining

Sometimes Refrigeration and Airconditioning parts and components should be drawn in order to show , plan, and install an aircontioning or refregiration unit.

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· Sketching, Shading and Outlining

Sketching is the drawing of a rough outline or rough draft version of what you want to draw. Sketching is used in preparation in drawing an object, or to just get a fast draft of how something will look. Whether you're sketching for fun or for a project, learning the proper technique can make the practice much more enjoyable.

When you start sketching, you should use a light hand and lots of short, quick strokes using your pencil. This will make it easier to sketch draw a particular object, and will allow you to erase mistakes much easier as well.

Importance of sketching

· Sketching will help you to easily edit, change or enhance the design.

· It is easy for you to show the rough draft of the product. How the product will appear and how to add more design in order to improve appearance or functionality.

· Your design of the finish product will depend on the sketch of your drawing.

Outlining is a process of making marks on the outer contours or boundaries of any shapes, objects or figure by the using lines.

Importance of Outlining

1. The drawn outlines give the product a clear view of the object.

2. The outline shows the shape and details of the design.

Shading -adds depth, contrast, character, and even tone to your drawings by the play of shadows and lights on your drawing. Learn how to shade drawings to improve your artwork, by trying some shadowing technique.

Importance of Shading

1. The design looks more realistic or life like.

2. It shows the play of light and shadow in the design of the object.

3. It adds beauty to the object, by the effects of the contrast and color.

REFRIGERATION PROCESS: AIR FLOW

Check Point:

Direction: Identify the symbols choose the letter of the correct answer.

Things to Do:

· Memorize and interpret RAC signs, symbols and data .

.Draw the following RAC electrical symbols of each component of a DOMRAC electrical circuit diagram.

· Identify necessary tools, materials and equipment according to blueprints of RAC plans, diagrams and circuits .

Key Points:

· RAC symbols are the language used to let you know how to read RAC work plans. The RAC symbol is used as shorthand and can provide you with all the needed information.