motor control wiring
- Thread starter jimbo123
- Start date
- Status
I found in my early years in the business that schematics just scared the chit out of me but then oneday I said if others can do this so can I.I would make up control logic in my mind and the try to draw a schematic,AKA Elementary Diagram of my thoughts.This helped me in my understanding and then I moved on to more complicated schemes with timers,relays,valves,sequential start ups and shutdowns,breaker control and large facility control panels with the latest electronic gadgets etc,then along came the PLC's and then the Distributive Control Systems AKA DCS and that only required two wires from contacts or ma signals from field devices to large system controllers that were programable and to me this was where all the fun was taken away, the smart college kids got to play with that stuff,Electricians and Instru. Techs got some of the responcibility back as the systems grew but the days of the hard wired relay control logic in industry was being phased out.It is still here as a small entity mostly in non-critical sevices in some process streams but not to the tune it was.
I still to this day enjoy playing with hard wired logic and the supporting schematic's........if you get into some of the more complicated schemes be sure once you have come up with a start up sequence and all is fine and then one day an upset requires a shutdown,,,,,,hmmmmm,thats where I going ,you can usually get it running fine with all the permissives but sneak circuits are common to the new kid on the block and you will seal a system in where you have open an OCPD somewhere to get your feet back on the ground.The checker should have caught it but chit happens.
Have fun with this endeavor,it challenging to say the least and rewarding as well.
dick
I still to this day enjoy playing with hard wired logic and the supporting schematic's........if you get into some of the more complicated schemes be sure once you have come up with a start up sequence and all is fine and then one day an upset requires a shutdown,,,,,,hmmmmm,thats where I going ,you can usually get it running fine with all the permissives but sneak circuits are common to the new kid on the block and you will seal a system in where you have open an OCPD somewhere to get your feet back on the ground.The checker should have caught it but chit happens.
Have fun with this endeavor,it challenging to say the least and rewarding as well.
dick
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ptonsparky
Tom
- Occupation
- EC - retired
In the last few years we had changed a couple small industrials to plc control. No way would I want rewind the clock and go back to hard wired timers, etc. Hats off to all the guys that pulled and terminated those miles of wire. The basic ladder logic is the same. The oops are just so much easier to correct.
Add the following to your reference documentation:
http://ecatalog.squared.com/pubs/Machine Control/0140CT9201.pdf
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
101121-1252 EST
jimbo123:
Are you familiar with thinking in terms of the logical functions "and", "or", "not", or with "nand", "nor"?
These are building blocks for use with any binary logic circuits, and motor controls fall into this category.
Assume a positive logic system. Meaning TRUE = 1, and FALSE = 0, then:
An "and" requires all inputs to be true for the output to be true.
An "or" (meaning "inclusive or" as distinguished from "exclusive or") produces a true output if at least one input is true.
An "xor" (exclusive or) is a two input function where the output is false when both inputs are the same, and is true when both inputs are different. This is the basis for building a binary adder.
A "not" function inverts the input. A normally closed contact on a relay would perform the not function relative to the coil input.
A "nand" is an "and" with a "not" on the output. So it can perform either the "nand" function, or by tying all inputs together perform the "not" function.
The "nor" is similar to the "nand", but with the input section being an "or".
Consider a simple motor circuit. A pushbutton to start and another to stop and a relay that stays in either controlled position until changed by the opposite pushbutton, or loss of power.
One logic circuit for this is (START or RELAY-ON) and NOT STOP = RELAY-ON.
Assume:
STOP is not pushed, then NOT STOP is true.
START is not pushed, then it is false.
RELAY-ON is not on, then it is false.
Under these conditions no power flows to the relay coil.
Even though NOT STOP is true, the other input (the output of the "or" function) to the "and" function is false, and the relay is thus not energized.
Same but press START. Now power flows to the relay coil energizing it and making RELAY-ON = true. Thus, there are two parallel path signal inputs to the "or" function that are true for at least a moment. So long as STOP is NOT pressed and at least one of the "or" inputs is present, then the relay will remain on. Since one of those two inputs is the relay itself it means that the relay will remain energized as long as power is present. You can press and release START as many times as you want and nothing changes.
If the RELAY is on and you press and hold the STOP button, then the relay will dropout and no pressing of the START button while the STOP button is pressed will cause any re-energization of the relay.
Restoring the STOP button to its unpressed state will again allow pressing the START button to re-energize the relay.
In positive logic parallel "normally open" contacts form an "or" function. And series "normally open" contacts form an "and" function.
.
jimbo123:
Are you familiar with thinking in terms of the logical functions "and", "or", "not", or with "nand", "nor"?
These are building blocks for use with any binary logic circuits, and motor controls fall into this category.
Assume a positive logic system. Meaning TRUE = 1, and FALSE = 0, then:
An "and" requires all inputs to be true for the output to be true.
An "or" (meaning "inclusive or" as distinguished from "exclusive or") produces a true output if at least one input is true.
An "xor" (exclusive or) is a two input function where the output is false when both inputs are the same, and is true when both inputs are different. This is the basis for building a binary adder.
A "not" function inverts the input. A normally closed contact on a relay would perform the not function relative to the coil input.
A "nand" is an "and" with a "not" on the output. So it can perform either the "nand" function, or by tying all inputs together perform the "not" function.
The "nor" is similar to the "nand", but with the input section being an "or".
Consider a simple motor circuit. A pushbutton to start and another to stop and a relay that stays in either controlled position until changed by the opposite pushbutton, or loss of power.
One logic circuit for this is (START or RELAY-ON) and NOT STOP = RELAY-ON.
Assume:
STOP is not pushed, then NOT STOP is true.
START is not pushed, then it is false.
RELAY-ON is not on, then it is false.
Under these conditions no power flows to the relay coil.
Even though NOT STOP is true, the other input (the output of the "or" function) to the "and" function is false, and the relay is thus not energized.
Same but press START. Now power flows to the relay coil energizing it and making RELAY-ON = true. Thus, there are two parallel path signal inputs to the "or" function that are true for at least a moment. So long as STOP is NOT pressed and at least one of the "or" inputs is present, then the relay will remain on. Since one of those two inputs is the relay itself it means that the relay will remain energized as long as power is present. You can press and release START as many times as you want and nothing changes.
If the RELAY is on and you press and hold the STOP button, then the relay will dropout and no pressing of the START button while the STOP button is pressed will cause any re-energization of the relay.
Restoring the STOP button to its unpressed state will again allow pressing the START button to re-energize the relay.
In positive logic parallel "normally open" contacts form an "or" function. And series "normally open" contacts form an "and" function.
.
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First I.d like to say thanks to the responses from you guys for your help here.
The help i was looking for was for motor control wiring that is for old systems.
I was given a wiring diagram for equipment that is from the 70's and i was lost.
I was given the job to get it working and got down to the second line of the wiring diagram and everything came to a halt. It had about 10 lines to follow.
One of the post had a download with the type of wiring control i am looking for ,it is a big help. Looking for something to start at the very beginning . Never really had any training with that . I'll have to find a course somewhere. Thanks to all you guys.
The help i was looking for was for motor control wiring that is for old systems.
I was given a wiring diagram for equipment that is from the 70's and i was lost.
I was given the job to get it working and got down to the second line of the wiring diagram and everything came to a halt. It had about 10 lines to follow.
One of the post had a download with the type of wiring control i am looking for ,it is a big help. Looking for something to start at the very beginning . Never really had any training with that . I'll have to find a course somewhere. Thanks to all you guys.
GeorgeB
ElectroHydraulics engineer (retired)
- Location
- Greenville SC
- Occupation
- Retired
I've had a binder for years from Siemens; there is a document in it, Siemens NS0/NV0 1978 which, on pages 5/19 through 5/68 has "Basic circuits, general list". Perhaps your sales engineer from Siemens can find a copy of that for you. The entire document is about 150 or 200 pages. I've never seen it on the web, but the Siemens "How to Read German Schematic Diagrams of Industrial Equipment" was there at one time. It carries a copyright symbol, so may have been a scan.
cadpoint
Senior Member
- Location
- Durham, NC
If you use at least two of the major search engines that have "images" on the web page go to that sub page and use the word(s); diagram ladder logic, diagram 345 motor control circuit, diagram XYZ.
The following site is one to download a publication titled "Wiring Diagrams A Reference Resource for CENTERLINE Motor Control Centers" Its good an free. I think it's somewhere on the Allen Bradely site but I can't find it. IF you have this and a recent AB catalong you will be well armed. http://www.scribd.com/doc/19767656/2100WD1
This is a SQ D publication titled "File 0140 Wwiring Diagrams"
http://www.scribd.com/doc/11538717/SQDWiring-Diagram-Book
Both of the publications are free and pretty good. Tehy down load as PDFs and are good books to have in your PDF library.
I will try to find them both on the ABB and SQ D site and I'll post that.
This is a SQ D publication titled "File 0140 Wwiring Diagrams"
http://www.scribd.com/doc/11538717/SQDWiring-Diagram-Book
Both of the publications are free and pretty good. Tehy down load as PDFs and are good books to have in your PDF library.
I will try to find them both on the ABB and SQ D site and I'll post that.
Link to the Square D page with the wiring diagram publication.
http://search.schneider-electric.us...client=xhtml&filter=0&site=default_collection
The Allen Bradley one is probably burried somewhere on their site but I can't find it today
http://search.schneider-electric.us...client=xhtml&filter=0&site=default_collection
The Allen Bradley one is probably burried somewhere on their site but I can't find it today
BILLY101
Member
- Location
- Telford, Pa
Control circuits consist of (2) basic designs. (2) wire control and (3) wire control. Separately or combined these two schemes cover the logic of ladder type control.
Keeping this in mind helps to understand the function of any given system.
Check out any of the published examples of control diagrams mentioned above and this will be clear.
Billy
Keeping this in mind helps to understand the function of any given system.
Check out any of the published examples of control diagrams mentioned above and this will be clear.
Billy
The SqD pub' is the same as I linked to in post #4 :roll:
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