Help With a Diagram Please

cattiebrie · Jul 12, 2017

I have a homework assignment and I need help please. After helping with the answer, can you please provide what is going on in the diagram so that I can understand?

Question: A discrete 120 V ac output module is to be used to control a 230 V dc solenoid valve. Draw a diagram showing how this could be accomplished using an interposing relay.

JZerb · Jul 12, 2017

http://www.plctalk.net/qanda/showthread.php?t=65998

cattiebrie · Jul 12, 2017

Thank you for the reply but is there a diagram that is much simpler and easier to understand?

cattiebrie · Jul 12, 2017

Here is an example of an easy diagram I am looking for.

Bit_Bucket_07 · Jul 12, 2017

cattiebrie said:
Here is an example of an easy diagram I am looking for.

Why are you looking for it, if you already have it?

jvdcande · Jul 13, 2017

Bit_Bucket_07 said:
Why are you looking for it, if you already have it?

I guess because he didn't go over his textbook well enough to understand what he's supposed to understand.

A lot of nowadays PLC programmers know how to write a program but lack basic electric knowledge. I think this situation is beginning to reflect on classrooms as well. It's about time the teachers start explaining that PLC programming is about electromechanics and that programming is only a means to control the stuff. But then again I know some teachers who never worked in the field...

Bit_Bucket_07 · Jul 13, 2017

jvdcande said:
i guess because he didn't go over his textbook well enough to understand what he's supposed to understand.

A lot of nowadays plc programmers know how to write a program but lack basic electric knowledge. I think this situation is beginning to reflect on classrooms as well. It's about time the teachers start explaining that plc programming is about electromechanics and that programming is only a means to control the stuff. But then again i know some teachers who never worked in the field...

+1

Bit_Bucket_07 · Jul 13, 2017

jvdcande said:
A lot of nowadays PLC programmers know how to write a program but lack basic electric knowledge.

Many of them also seem to think that there is no need for them to develop an understanding of the process that they are attempting to control. Learning to write code efficiently alone doesn't make someone a qualified PLC programmer.

GaryS · Jul 13, 2017

If you wanted to put a different curve in this
You could use a voltage doubler and eliminate the relays

their at many ways to achieve the same end this is just one of them

sparkytex · Jul 13, 2017

Many ways to accomplish this. I would use the 120v output from the card to actuate and isolation relay. The Isolation relay would actuate a separately sourced 120v to the coil on the contactor for the 230V DC Solenoid.

AutoMax · Jul 13, 2017

FWIW gentlemen, I assume by the original posters user name it is a lady (name is from R.A. Salvatore's fantasy novels.)

The diagram is showing the coil of the interposing relay being energized by a PLC output. When this coil is energized, the normally open contact of the interposing relay is closed, energizing the coil of the motor starter. And tell your professor one doesn't use this type of scheme without overcurrent protection or feedback from the motor overloads, otherwise resetting the the motor starter will cause the machine to start. Also (at least in the USA) we don't typically refer to a motor starter as a solenoid.

Tom Jenkins · Jul 13, 2017

jvdcande said:
i guess because he didn't go over his textbook well enough to understand what he's supposed to understand.

A lot of nowadays plc programmers know how to write a program but lack basic electric knowledge. I think this situation is beginning to reflect on classrooms as well. It's about time the teachers start explaining that plc programming is about electromechanics and that programming is only a means to control the stuff. But then again i know some teachers who never worked in the field...

+1

JohnCalderwood · Jul 13, 2017

but the diagram does not relate to the question surely....

Is it not something like the attached?

cattiebrie · Jul 13, 2017

I am a returning student (over 10 years out of school) and they threw me into a class where I have forgotten the lessons taught from the prerequisites of the course I'm taking. I would like to get up to speed by understanding the answers you guys are providing.

boneless · Jul 13, 2017

Ask lecturers if you are allowed to sit in the classes you forgot, often they will allow you to do so.

I would also recommend Lydia, my uni offers free access to Lydia. Or MIT Opencourseware.

Help With a Diagram Please

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