Electrical drawing help

[kryanl]

Hello,
I have a mechanical background, and I was wondering if someone can give me a brief definition/description of the main types of electrical/controls drawings: one-lines, elementaries, and loop diagrams. Also, is there a website that gives information as to how to read these types of drawings? I am just looking to get a very basic understanding, so I do not always have a blank look on my face when one of our electrical engineers is trying to tell me wha a drawing says.

Thanks for any help,
Kay

 

[fsmyth]

Be aware that symbols in the electronics world and
the electrical world can differ somewhat, and there
are variations on both. Electricians do it funny.
So do Europeans. <big smiley for the humor-impaired>

Here are some to get you started:

http://www.tpub.com/content/doe/h1016v2/css/h1016v2_19.htm

Any library should have a reference text for either, but
there is plenty available on the web.
<als>

 

[dbaird]

Check:

http://s38.yousendit.com/d.aspx?id=17WJM13JX6H7J0K3RJ0XOVGK35

http://s39.yousendit.com/d.aspx?id=2YIV5BQVVNVZC0HW59DS9A2DNW

David Baird
mrbaird@hotmail.com
Sr Controls Designer
EET degree.
Journeyman Electrician.

 

[ScottyUK]

Hi fsmyth,

No humour-impaired people over here. We get far too much entertainment looking at the dumb symbols you Americans dream up...


----------------------------------

One day my ship will come in.
But with my luck, I'll be at the airport!

 

[peebee]

Hey, I resemble that comment.

It probably took me 5 minutes to figure out your transformer symbols the first time I saw them. Transformer windings don't look like circles, everyone knows that.

 

[jraef]

When I frst saw them, I thought they were two "male" symbols conjoined! (not that there's anything wrong with that).

 

[MagneticFlux]

This is in response to the first part of your message...

The drawing types are as follows:

1) One Line Diagram - used when information about a circuit is required but not the detail of the actual wiring connections or operation. This diagram is usually what estimators/electricians will use to establish wire counts and routing. i.e. Conduit from point A to point B with 25 - #14MTW control wires.

2) Line Diagram - a.k.a. Ladder Diagram, a.k.a. Logic Diagram, a.k.a. Elementary Diagram. This drawing type depicts the LOGICAL OPERATION of the control circuit. Provides a fast, easy understanding of connections, use of control devices and loads (control loads only, like starter coils and solenoids). This is the goto drawing when problems occur and should be included with ANY electrical control system.

3) Wiring Diagram - This drawing shows the interconnection and installation of control devices and loads. This drawing would be used to indicate the higher voltage elements of the control system, such as the wiring of motor starters to motors or terminal blocks for field connections. The best way I can think of describing this would be a Panel Layout Drawing. Layout Drawings would show the components, wire way, terminal blocks, pilot devices, etc. with the interconnecting wiring plotted on paper just as you would want it to appear when the panel is assembled.

As for the Sybology, I would recommend you goto

http://www.necanet.org.

Their symbols are actually NEMA symbols. You may have to pay for them, but they are yours forever and rarely change.

I hope this was of some help to you....

 

[ScottyUK]

Loop diagrams are used with, you guessed it, control loops. They typically show the sensing element, controller and output devices, plus any interconnection to other controllers for tracking, ratio control, etc.

One major drawing type you didn't mention was the P&ID, or Process and Instrument Drawing which is common in any industry using fluids flowing in pipes e.g. petrochem, powergen, chemical production, etc. These drawings show the layout of the plant in terms of flow, not physical layout, and show the relative positions of the control elements, transducers, piping size, process fluids, etc. These are often the among first drawings to be produced and from these the detailed loop and ladder logic drawings are developed.


----------------------------------

One day my ship will come in.
But with my luck, I'll be at the airport!

 

[laundry]

Hi
Why dont you just aske your electrician to explain how to read a drawing and a schematic.He will explain it better than a book,as you can aske him questions and he will give you an answer but the book will not.

Barry.

 

[rbulsara]

For a mechanical individuals may be the follownig will bbe of help:

Liken the electrical one line to a water system's flow diagram.

Voltage or electric pressure is water pressure or head.
Current is like water flow.

Power is Power like Q*H

The circuit breakers/switches could be thought of as valves expect CB's and swithes with fuses can open (akin to closing of a valve) to prevent flow of current when above set limits.

Condcutors like pipes
Resitance is friction. (dont worry about capacitors and inductors at this stage, but they are equivalent to stiffners or damping devices respectively)

Transformers are like pressure reducers or boosters.

Generator would be a pump or water source, more like a local well.

Utility source is more like main reservoir supply.

Elecrical leakage is like a water leak.

Short circuit would be pipe break (or worse)

Switchboard and panelboards are akin to a manifold with bunch of taps and valves.

Now you when you see the symbols (assuming you learnt them, not a diffcult task) you will understand their functions too and would understand the system better.

 

[boreholelogger]

If I were you, I would get a hold of your electrical engineers CAD software and go through all the components that he/she uses the most one by one and search for a description of each component on the internet. At least if you have the software it will give you the electrical name of the component you want to learn about and you know what you are actually looking for.

 

[RalphChristie]

The best would be to ask an electrical collegue to explain it to you, like laundry and boreholelogger suggested. First of all we do not know what standards you are using,(IEC, IEEE, etc) because there are some differences between the different standards. And if that is not enough, there is also different ways of doing between different electrical companies. The drawing of Siemens, for instance, is very difficult (for me) to read, because I was used to the old AEG-drawings.

 

[smitanuj]

i think you should sit with some electrical engineer for an hour and he will explain everything. It is easier than mechanical drawings. the only tough job for you is to remember the symbols.
Anuj Agarwal