Need help building specific Motor Control Circuit

[ZappyAppy]

Here is the circuit parameters I am trying to build, I just can't seem to figure it out.

• When the start button is pressed, motor 1 turns on
• Motor 2 will start 5 seconds after M1 has started.
• Motor 3 will start 6 seconds after M2 has started.
• When the stop button is pressed, M3 stops immediately.

-M2 will stop 4 seconds after M3 has stopped.
- M1 will stop 3 seconds after M2 has stopped.

Any help is much appreciated. I'll try uploading what I have so far

 

[Lucien Nunes]

What technology were you planning to use to implement this? Obviously it can be done with four independent timers and a few relays, you can get the four timers in one multi-channel programmable timer, or you could use a PLC. Are there any special requirements for operator safety etc? Are there additional conditions for aborting the sequence, e.g. if the stop button is pressed before motor 3 starts or the start button is pressed before motor 1 stops?

I have to admit that in my usual electromechanical way, as I read the question I immediately visualised two declutching spring-return camswitches, one for starting and one for stopping...

 

[SheffSimon]

Here is the circuit parameters I am trying to build, I just can't seem to figure it out.

• When the start button is pressed, motor 1 turns on
• Motor 2 will start 5 seconds after M1 has started.
• Motor 3 will start 6 seconds after M2 has started.
• When the stop button is pressed, M3 stops immediately.

-M2 will stop 4 seconds after M3 has stopped.
- M1 will stop 3 seconds after M2 has stopped.

Any help is much appreciated. I'll try uploading what I have so far

Is this an industrial/commercial project or just a thing for your own use?

Either way, either relay logic or a micro PLC or Arduino or Raspberry pi.

 

[David Prosser]

6ED1052-1HB08-0BA0 | Siemens LOGO! Series Logic Module for Use with LOGO! 8.2, 24 V dc Supply, Relay Output, 8-Input, Digital Input | RS

uk.rs-online.com

Something like this should cover that task easily.

 

[Julie.]

As has been said above a plc would be the most usual way, but it depends on the process, in most processes it's not just the timing that matters, for example if M1 is an intake fan, then it would be usual to use a flow sensor to ensure flow before you start M2 - the output fan say, and again a flow sensor on this fan before you start M3 etc...

Quite often there is a whole logic - what happens if one motor trips, does the process continue or shut down - is this the same sequence etc.

The advantage of a plc is that if the customer missed some vital step out when explaining the requirements, it's an easy change - just a bit of code.

If you use hard wired logic with timers initiated from aux contacts on the previous motor's starter (how it should be done) then even minor changes could mean a whole redesign.

I would reserve hard wired logic for only the systems that are absolutely nailed down and the chance of a change is practically zero.

 

[ZappyAppy]

I just need to make a ladder diagram of it for school.

 

[Julie.]

I just need to make a ladder diagram of it for school.

Ah OK,

In that case try to do it yourself and post your attempt, people will help you towards a correct answer but won't do it for you.

 

[Spoon]

I just need to make a ladder diagram of it for school.

As above mate.
Give it your best try first, then we will advice.
Better for you to try, then you can then learn from the exercise.
If you have problems with the 'Attach files' function then just copy/paste it directly into the chat box.

 

[Darkwood]

As a forum we are all too happy to help when needed but as others have said we cannot do assignments, homework and/or projects for you that are active part of your coursework we need you to show us how you think it is done and we can kind of nudge you in the right direction if needed.
If you provide us with your attempt please include the full question as written in your assignment so we can properly interpret whether it meets the requirements of what exactly the question asks you to do, if you have misinterpreted it in anyway that will be passed on to us too if you do not give it word for word thus possibly getting incorrect advice as a result.

 

[ZappyAppy]

As a forum we are all too happy to help when needed but as others have said we cannot do assignments, homework and/or projects for you that are active part of your coursework we need you to show us how you think it is done and we can kind of nudge you in the right direction if needed.
If you provide us with your attempt please include the full question as written in your assignment so we can properly interpret whether it meets the requirements of what exactly the question asks you to do, if you have misinterpreted it in anyway that will be passed on to us too if you do not give it word for word thus possibly getting incorrect advice as a result.

Here is the copy and pasted question:

Design a control circuit such that:

• When the start button is pressed, M1 turns on
• M2 will start 5 sec after M1 has started
• M3 will start 6 sec after M2 has started
• When the stop button is pressed, M3 stops immediately
• M2 will stop 4 sec after M3 has stopped
• M1 will stop 3 sec after M2 has stopped
• All motors and the entire control circuit will shut down if any motor O/L trips out

Here is my attempt at it. The teacher says its wrong but declines to say why. I guess I just need a bit of help before I attempt it again. Let me know if this circuit can be saved or if I should just start fresh. Thanks for the help everyone, much appreciated.

 

[Spoon]

What does pin 6 of the Time Delay relays do?

 

[Julie.]

OK, I am afraid to say the errors are fairly classic!

You have thought through each step as you expect/want it to work, rather than stepping back and reviewing what will happen at each stage.

For example, I can see td1 contact closes starting m2, and td2, later in the sequence you need td4 to receive the same signal, for shutdown and maintaining, so that's also connected to m2 and permanent.

Therefore look at ALL the paths between m2 and permanent supply, you might spot something.

This isn't the only issue BTW, but follow the same logic and you will see the other errors.

 

[Darkwood]

I was just making sure we got the full details for members to respond to, in the real world there is so much more to consider and regulations to implement usually, regulations that can effect the whole design from the start, this is clearly just asking for a basic concept of a time delayed step procedure assuming they want you to use basic timer relays and contactors and auxiliary contacts to achieve the design.
You will probably want to utilise timer relays which can do a dual function IE a settable delay on and settable delay off in the same control line, many models will only let you choose one or the other or just having 4 seperate units would achieve the same, again in the real world cost is to be considered but not here.
Ideally you would employ the use of a PLC and write a very simple logic program but the method you choose is relevant to what stage of the course you are in and whether you have covered some option yet or not, only you know that.
We could give a clever design but it won't really be suitable for your course if you haven't covered it, your tutor will be looking to see if you understand what has been covered so that is where your design needs to come from.