Symbols 1

[itsmoked]

I'm drawing a schematic for a multiple pump hydraulic control system I'm designing. It has the usual pesky front panel covered with a matrix of the typical, grossly expensive, 30mm type selector switches.

I will be using some of those switches with mind numbing contact specifications. Essentially a double throw(center off) triple pole, spring return to center.

Keep in mind in the spirit of all these switches they are ALL internally and externally purely single pole, single throws that you must actually jumper to make single pole-double throw.

The Old Schematics I am upgrading from show these in single pole. I find the symbol used to be horrible and unclear.

Can someone direct me to a "good" symbol or where I could forage for one.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Hi electricpete.

Out of curiosity waross, how do you get 3 positions on a pushbutton?

There used to be a three position pushbutton on the market.
I used a pair of them on a small boat I had with twin outboard motors.
The buttons had mini mushroom heads. Pushing them down would activate one circuit and lifting them would activate the other circuit. I wired them so that pushing down would kill the engines and lifting them up would start the engines. They may have been made by Cutler Hammer.
respectfully

 

[stevenal]

More symbols can be found in IEEE 315. A quick look showed only the table method of showing this application.

 

[itsmoked]

Hi waross! Yes I was aware that "my" symbole was of the double throw - 2 single pole switch type.

I am using AB selector switches and spent all of my last Saturday trying to understand their spastic catalog and online configurator. This is after drawing pictures of what I wanted faxing them to AB tech support and being given absolutely wrong advice as to what devices to order(this after the dealer couldn't answer me and sent me to tech sup).

It seems to me that you cannot get a three terminal device (SPDT) at all! Everything is based on the "Push Button" except when you want selector switches everything is turned 90 degrees and the 'push' becomes a cam lobe. I actually wanted SPDT in some cases but that requires two SPST jumpered together. Not a big problem, just required a different pradigm.(and a saturday and part of a thurs and fri. argh!)

stevenal; Thanks.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Hi Keith;
I understand your frustration.
One big advantage of the paradigm used to be spares stocking. One or two basic double throw contact blocks could be used in virtually any selector switch or push button in the plant. Except of course for the exceptions. SquareD had a contact block with slightly different clearances that was only used with the lever operated selector switch. If you used a standard contact block, the switch operator would destroy it. They sold us a lot of the wrong contact blocks before we found that out.
Just to make your day, I bet you a cup of coffee that you miss at least one of the little jumpers on an spdt. Been there, done that.
Respectfully

 

[itsmoked]

Yer on!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[kontiki99]

I think we'd probably use something like this in an aircraft wiring diagram.

Dashed lines represent a mechanical link.

Black triangles represent a momentary contact.

http://kontikilink.home.mindspring.com/Switch.tif

 

[machmech]

Hi Keith

I don't think your symbol is all that bad, the only thing I might change is the word "HAND" to "MAN" instead.

I did spend about 45 min searching for something more definitive with no luck, this in mind your symbol is just about awesome. Other then using a toggle or rotary style switch it seems there are no options. That does seem like a very odd kind of switch normally a push/pull type is for E-stop operation.

Chuck

 

[itsmoked]

Hi Chuck!

Thanks for the complement. I thought mine were pretty good for a first hack but finally just reverted to the the original one at the top since that was the NEMA symbol used on the customer's system I am replacing. I figured (after direction from others above) they could hardly complain if I duplicated what they had. Thanks for the effort and feedback.

You know, I absolutely hate the term "HAND" I think it is lame. I have in-fact never ever heard of it before this job. But this customer is infatuated with it and wants "HOA" (pronounced 'hoe ah') switches on everything and everywhere. So I can either switch to "manual" or again go with the flow. The only thing I can see going for it is H-A-N-D is the same length as A-U-T-O and hence allows better visual symmetry in panel labeling.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Hi Keith,
HOA may have been chosen as a more descriptive abreviation than AOA.
Respectfully

 

[itsmoked]

Hi waross;

???? You mean MOA? AOA??? I've actually seen MOA many times.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

Hi Keith I don't know what I meant. Must have been a seniors moment.
I looked in a couple of catalogues and you can buy either nameplate. Hand-Off-Auto or Man-off-Auto. Make your choice and you will be correct.

The name plate for the three position push button would read "PUSH TO STOP PULL TO START" (GE) or "PULL TO START PUSH TO STOP" (SquareD). It is not the same device as the "PUSH TO STOP PULL TO RESET" push button. One is a two position, maintained position button and the other is a normally centered button with a spring return push and a spring return pull.

BTW, do spaces count as characters? They do have a character code.
lol
Respectfully.

 

[fangas]

Hi Keith,

I would get rid of the dashed vertical lines and the X's on the power & controls lines.

Then replace with something like this.

OFF
Hand Auto
---------------o o--------
X00
---------------o o--------
00X
Place the 0 & X's as close to their respective line and contact as possible. And, of course, include the operator & contacts.

Every plant electrician I've worked with would recognize this as denoting the contact state for each switch position. At least in the US.

Ed

 

[itsmoked]

Thanks fangas; I will pull them and see what it feels like. They are what bothers me most I think.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[BJC]

Here are a couple of more good references.

http://literature.rockwellautomatio...vanced_search.hcst?passedLangVal=EN - English

Search for 800-2.0

http://ecatalog.squared.com/techlib/advanced_search.cfm

and
search for Document No. 0140CT9201

The NEMA-ISA format allows for a lot of situations that would be hard to cover with any other drawing method. The "Push-Pull", Spring Return", "Pull to Lock" have a lot of posibilities. If you going to do a lot of work with with control switches get one of every type of operator and contact block and keep them in your desk.
Jaref is right about the DIN and European sybology. You can describe allmost any situation with it. By the time you understand you may wonder why you didn't become an Egyptologist or study Chinese.

 

[itsmoked]

Oh yeah BJC; That's some pile of info there (800-2.0) excellent thank you... another night of light reading I see....

Oh WOW!! That Snider doc is chock full!! Sweet. I bet those two took you a month to find the first time...

Many thanks.

Oh and foreshore you can bet, I was wishing, I had one or two switches in my desk when I started the switchtology effort.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[BJC]

itsmoked
I have had hard copies for years. I sent the title pages to the local reps and asked them to find the links. Be kind to sales reps. They can help you a lot.

 

[machmech]

Hello bjc

Star for you, Thanks

Chuck