With this desire, I recalled that I have the book Fundamentals of Motor Control, by the NJATC, and I haven't read it. So, that's what I am doing --I'm desperate and in need of electrical review. Though I hope it goes well because sometimes, the books of NJATC feel like they were written by an orangutan.
So, here goes nothing....
Ch 1: The Boring Beginnings of Standardization
( Don't get me wrong, standardization is essential to the industry. It's just boring to read about.)
1-2 NEMA stands for National Electrical Manufacturers Association
In 1910, the Associated Manufacturers of Electrical Supplies and Electric Power Club promoted standardization in the industry. In 1926, there two entities did a little hanky-panky and became NEMA. NEMA developed standards for the nation, and in 1929, it started the "Safe Electric Cord" program and brought attention to the use of safe power cords. It played at major role in the efficient production of material for the military during WWII, and its standards helped after the war had ended. Nowadays, questions arise over NEMA because the world is more global and national standards interfere with a global standardization ..in this area of the book, it talks about NEMA's specific standards, but haven't we already suffered enough?
1-3 IEC is International Electrotechnical Commission- reminds me of technicolor
It is centered in Geneva, Switzerland and was formed in 1906 to promote the co-operation of standardization in technical societies of the word. In 1938, it produced the IEV, the International Electrotechnical Vocabulary, now known as the Electropedia (No, I didn't make this shit up). In 1950s-60s, the IEC initiated standards for lasers, maritime equipment, medical, semiconductors, radio TV, and electroacoustics. (So basically, everything that is fun) Also recently, it has a Affiliate Program that helps third world countries follow in the footsteps of the IEC.
Everything else in Chapter 1, lets just skip.
Chapter 2: Manually-Operated Devices (or manually operating your mother-on and off all day)
2-1 Input Switching Devices
( I can't stress enough how important this section is. When working on relays, you'll want to know what kind of fucking switch your using or else you'll be crying tears of salt by the end of the day. Right now, you'll take it for granted how easy it is, but when figuring out relay logic later on, you'll wish you paid better attention)
Types of Manually Operated Input Switches
Pushbuttons
Selector Switches
Key
Drum
Foot
Joystrick
(....all these switches sound kind of kinky)
Switch Operator
The operator is the device or mechanism used to change the contact positions in the contact block. (In a Pushbuttom switch, it's a button, and in a selector switch, it might be a toggle.)
Lots of switches have normally two states.
NO (normally open)
NC (normally closed)
With the switch operator in the non-actuated position, the NO contacts are opened and the NC contacts are closed.
(Enough said. Simple! I know!, but this will FUCK U UP)
Even in the text, it says, it tries to refer to things as 'activated' and 'non-activated'
Switch Pole
The term Pole indicates number of isolated (not electrically connected) sets of contacts within a switch assembly.
(From what I understand, it's a single circuit within a switch. A single pole would be one input and one output. A double pole would be 2 inputs 2 outputs, two sets of contacts)
Switch Throw
The term a throw indicates the number of current conducting positions or contact positions associated with each pole.
ST-Single Throw- you have NO or NC
DT-Double Throw- the pole has two contact positions, with a common wire between them C.
Center-Off- Some switches have center off position.
(The Pole and Throw Stuff is Important- we are going to find a test for it later)
Single Break and Double Break Contacts
SB Single Break switches interrupt circuit flow at one point.
DB double break switches use two sets of contacts to interrupt the circuit at two points.
The double break provides a higher level of protection against a higher current. Though, I've never seen the inside of a double break switch. I wonder how it looks like.
(Image Source = http://electriciantraining.tpub.com/14175/img/14175_135_2.jpg)
Momentary and Maintained Operator
Momentary- The contacts change state when actuated, but then return to original state. They spring back to the original position and are sometimes called spring return. (These are used a lot in HVAC systems)
Maintained- The contacts change state when actuated and remain that way. It has to be physically reset before it will function again. Generally, used for emergency stops and things like that.
Pushbutton Switches- Welcome to the Kinky world of Pushbuttons, and yes, it's always that big Red Button that you are just Dying to Press
Extended Operator-extended so that it is easy to press in an emergency
Flush Operator-Flush so you don accidentally press it as much
Guarded Operator-so you don't accidentally press it. You have to work to push that bitch.
Mushroom Operator- It kinda looks like a dick, and it's really really hard to miss.
(source=http://3.imimg.com/data3/NQ/UV/MY-1225448/push-button-switches-250x250.jpg)
If you think you can't take more pushbutton, oh wait, there's more!
Interlocking Pushbuttons-the two pushbutton operators are linked to a single or multiple contact blocks
(Image Source = http://schneider.thomasnet.com/Asset/9001KR11GR-Push-Button-Operator-30MM-TYPE-K--Options.jpg)
Three Position Push-Pull Pushbuttons- It sounds sexy, and it is. It has 3 positions: momentarily out, a maintained center and momentarily in
And there are othr pushbuttons, but I'm getting tired of talking about PushButtons
Next ....
Selector Switches -are control devices in which the operator is rotated to actuate contacts in attached contact blocks.
Parameters of selector switches are
Physical Style of Operator
The number of Positions
Selection of maintained spring return for each position
the number and types of contacts
the type of contact blocks
the type of legend plate- sounds like something from zelda
Zelda and the selector switch, which Adventure do you Choose?
(image source= http://i01.i.aliimg.com/img/pb/235/113/433/433113235_794.jpg)
Drum Switches- are a variation of the selector switch. It is generally 3 position and used in motor control.
(image source= http://static.schneider-electric.us/assets/idw/4/09008926807a5d63.jpg)
There is a big informational sheet on this particular sheet, but I'll study the details of this particular switch a little later. I'm sure I'll get more information that I know what to do with.
Foot Switches
(image source = http://www.automationdirect.com/images/overviews/foot_switches_300.jpg)
Joysticks!!! My favorite! It's so phallic. The deliverer of Joy.
(source = http://amigakit.leamancomputing.com/catalog/images/sl-6603-gold_rgb_001.jpg)
Apparently, there is a gaming competition for these things.
After that, the rest of the chapter is about outputs, which is buzzers, horns and lights.
So, we are done for now. I hope you enjoyed this!!
I sure did.
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