# how to design motor control with float switch?



## wdestar (Jul 19, 2008)

Junior

If you need some help, study the books.

The giveaway was "if it can be possibly realizable"

I'm sure it's :realizable".

Let me guess... you lean to the left?


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## salsar1978 (Aug 23, 2014)

?????? What are you talking about?


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## wdestar (Jul 19, 2008)

And this, ladies and gentlemen, are the "folks" who are going to lead us (US) into the future. God help us.


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## salsar1978 (Aug 23, 2014)

*Mr. show off*

Why posting unnecessary comments? 
I'm learning man....I guess you weren't born expert, were you?
Well, I'll let YOU lead the US to the future...hhhhh.
I don't know how the US gives people like you the opportunity to teach our students? If you are really a teacher. No wonder why China is taking the lead...hhhh


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## Big John (May 23, 2010)

All I can say off hand is you need a timer. Slamming a motor from forward immediately into reverse, especially in a high inertia application like a pump, will trip your protection, or failing that, destroy the motor.

What task are you trying to accomplish with this setup?


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## John Valdes (May 17, 2007)

If you are serious, take out a paper and pencil and draw two vertical lines on each side. Or print out the attached "ready circuit" to this post. Then add the devices and connect them within the framework of the schematic drawing presented.
Here is one ready to draw provided by EZ Schematics Pro.


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## salsar1978 (Aug 23, 2014)

Thank you for the reply, yes I can draw ladder diagrams and I have designed control circuits , but for this particular circuit I've tried to draw a ladder diagram for it but I couldn't find the solution. I guess it's not possible to make this circuit with the given components. So I just thought if anybody can help me with that. Thank you


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## glen1971 (Oct 10, 2012)

salsar1978 said:


> Thank you for the reply, yes I can draw ladder diagrams and I have designed control circuits , but for this particular circuit I've tried to draw a ladder diagram for it but I couldn't find the solution. I guess it's not possible to make this circuit with the given components. So I just thought if anybody can help me with that. Thank you


With the given components it can be done.. Will it last?? Not a hope... You'll be changing motors and starters more often than you can imagine.. Not to mention you'll be running it on one microswitch in a level switch... Kind of a tight margin of control....


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## Wirenuting (Sep 12, 2010)

salsar1978 said:


> Thank you for the reply, yes I can draw ladder diagrams and I have designed control circuits , but for this particular circuit I've tried to draw a ladder diagram for it but I couldn't find the solution. I guess it's not possible to make this circuit with the given components. So I just thought if anybody can help me with that. Thank you


Is this homework?


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## salsar1978 (Aug 23, 2014)

no it's not a homework, I'm done with school years ago, one of my friends works in beverage factory asked to help him figure this out.


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## salsar1978 (Aug 23, 2014)

glen1971

Did you figure it out?


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## Wirenuting (Sep 12, 2010)

salsar1978 said:


> Did you figure it out?


I figured it out years ago.
Worked great to clear a clogged sewage pump.. 

But you still haven't provided much info.. What, were, why, ect..


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## martindag (Oct 30, 2009)

That's funny this week its prety much the samething im doing motor control of chillers with floats and all with lights and interlock.

Like they said having a timer would be the bare minimum to have for this control to make sure you have X time when reversing your rotation.

other than that buy some extra relay if you are not sure and Aux contact on your contactor for extra contact


or download something like Zelio soft 2 it's free to simulate your control.


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## salsar1978 (Aug 23, 2014)

Wirenuting


one of my friends works in beverage factory asked to help him figure this out. I don't know much detail about the process where he needs it, but he did mention something about
They're adding new unit and upgrading some equipments.


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## dronai (Apr 11, 2011)

Salsar, take a piece of paper, and draw what you think, and post results for help.


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## salsar1978 (Aug 23, 2014)

Ok I'll try to post , it might take time cause I'm using cellphone


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## martindag (Oct 30, 2009)

Yeah give it a try atleast, post your result if possible and we will help you out


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## salsar1978 (Aug 23, 2014)

Thank you, believe me I've tried many times, but I'll try to post


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## salsar1978 (Aug 23, 2014)

I don't know where to place the float switch to go between forward and reverse without losing the seal in, plus when turning the selector switch to start position none of the coils should be energized.


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## Wirenuting (Sep 12, 2010)

salsar1978 said:


> I don't know where to place the float switch to go between forward and reverse without losing the seal in, plus when turning the selector switch to start position none of the coils should be energized. [/URL][/IMG]


Here is a basic 3 phase reversing circuit. 
The float would be a 1st state permissive item, it can be placed before the stop button..
This circuit "DOES NOT" show a timer that would allow the motor to come to a complete stop before reversing.


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## salsar1978 (Aug 23, 2014)

glen1971 said:


> With the given components it can be done.. Will it last?? Not a hope... You'll be changing motors and starters more often than you can imagine.. Not to mention you'll be running it on one microswitch in a level switch... Kind of a tight margin of control....


Could you please send me the diagram if it's possible? Or give me hint about it, it's really driving me crazy. 
The diagram posted above is not what I'm looking for, it uses two push buttons to switch between two directions, the problem is I have just float switch to do that. Thank you.,


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## martindag (Oct 30, 2009)

Few tips maybe i would recommend you:

Make sure to add timer on your float if you can that way when filling the tank or whatever you got some wave in there also with that timer you will be able to add alot more contact NO and NC to your float.
So adding like a 5-10second timer to it would be good.


You need a other timer to block the motor to go reverse too quickly in case it was running forward, you will destroy your motor.


You need also to make sure that you can't for exemple press stop right after the float is activated and restart it, you need a interlock in your timers for this.

You need also interlock for each Forward and Reverse contactor to make sure you cant activate them while its running.




If i had to do it the material i would use ( and i tried it for fun on simulation)

Would be:

3x Timer on-delay with 2NO/2NC contact 0-60sec
(1 for the float timer incase of wave, and 2 for each contactor ... (Actualy you can buy contactor with this function on it... look at schneider catalogue).

2x contactor for Forward and Reverse

1x Relay to say that your system is Running 2NO 2NC



If after trying again and show your result, i will send you the control diagram but for this i need a exemple that you worked for it.
`


Recommended step i try to follow:

1- Do your Grafcet to know your condition
2- Do your Ladder, if possible on a PLC programming software with simulation on it (That way it won't cost you a motor to test and find error in your control)

3- Find the material you need to do the job

4- Connect everything

5- Try it live with control voltage ONLY

6- If everything is good try it with your primary voltage live.


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## Safari (Jul 9, 2013)

Martindag.wich simulation software did you use ?


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## martindag (Oct 30, 2009)

I like Zelio soft 2 its free or i got also LogixPro i paid for it for PLC training like 25bucks but the 1st page is a IO list with all type of contact, so its great to build a control from it and test it.


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## Safari (Jul 9, 2013)

Am at work at the moment and I got some free time to figure out the circuit. Here it is I hope you get to see it my phone camera is of low quality.if you dont see it clearly let me know I will borrow one.

Explanation
I pass my hot through the overload to the stop button and to the selector switch.

It then goes to the NO contact of the forward contractor. Note here I didnt use the hold one because I assume your selector switch is non spring return it will hold.

From here it passes through the NC contact of the reverse contactor.this is for interlock purpose.

It then passes through NC contact of a relay to the coil of the first timer. 

Now we use the NO contact of the timer to supply the coil of the forward contactor. The motor runs in fwd mode.

NOTE:
I have rotated the schematic in my next post.


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## Safari (Jul 9, 2013)

Let me rotate the image

Sent from my HUAWEI Y210-0100 using Tapatalk 2


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## martindag (Oct 30, 2009)

Thinking about it you could also take a Relay connected to your float with a Timer in parrallel could work also.


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## Wirenuting (Sep 12, 2010)

nickson said:


> Am at work at the moment and I got some free time to figure out the circuit. Here it is I hope you get to see it my phone camera is of low quality.if you dont see it clearly let me know I will borrow one. Explanation I pass my hot through the overload to the stop button and to the selector switch. It then goes to the NO contact of the forward contractor. Note here I didnt use the hold one because I assume your selector switch is non spring return it will hold. From here it passes through the NC contact of the reverse contactor.this is for interlock purpose. It then passes through NC contact of a relay to the coil of the first timer. Now we use the NO contact of the timer to supply the coil of the forward contactor. The motor runs in fwd mode. NOTE: I have rotated the schematic in my next post.


I PMed quit a bit yesterday and he couldn't give any additional info. He said that only the items he listed could be used, no timer. 
Then kept asking for a drawing to be sent to him. 
But he couldn't even tell me what size/type motor his friend had.


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## dronai (Apr 11, 2011)

Wirenuting said:


> I PMed quit a bit yesterday and he couldn't give any additional info. He said that only the items he listed could be used, no timer.
> Then kept asking for a drawing to be sent to him.
> But he couldn't even tell me what size/type motor his friend had.


 And you did give him a schematic to start working things out.


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## Big John (May 23, 2010)

I originally thought _wdestar _was being rude, but now it sure sounds like we did someone's homework for him.


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## Wirenuting (Sep 12, 2010)

Big John said:


> I originally thought wdestar was being rude, but now it sure sounds like we did someone's homework for him.


He said it wasn't homework and a friend told him it could be done. Almost sounded like he wanted to copy what his friend told him. 



dronai said:


> And you did give him a schematic to start working things out.


Only because he couldn't spell google.


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## Safari (Jul 9, 2013)

...........


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## Safari (Jul 9, 2013)

Wirenuting said:


> I PMed quit a bit yesterday and he couldn't give any additional info. He said that only the items he listed could be used, no timer.
> Then kept asking for a drawing to be sent to him.
> But he couldn't even tell me what size/type motor his friend had.



That must have been a homework indeed. He got me


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## Wirenuting (Sep 12, 2010)

nickson said:


> That must have been a homework indeed. He got me


But you did try an help. 
It wasn't a waste of time, I saved your drawing on my phone... Ya never know when ya need another persons ideas.


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## JRaef (Mar 23, 2009)

LOL, I'm sitting here reading this and wondering "Where are my posts? I know I posted on this, but I don't see them. Was I too offensive or something?"

Then it dawned on me that the OP has posted this in another forum and I answered there. In the other forum, he once mentioned it as a pump, then later a compressor. So I mentioned that this, combined with the lack of details and a steadfast insistence that the solution have ONLY the components listed meant that he is either a student (who has figured out that admitting he is a student gets him banned) or he is a troll, baiting us with a puzzle that cannot be solved as stated. Since my posting of that in the other forum, he fell silent there and now has appeared here.

Hmmm... :shifty:


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## JRaef (Mar 23, 2009)

nickson said:


> Am at work at the moment and I got some free time to figure out the circuit. Here it is I hope you get to see it my phone camera is of low quality.if you dont see it clearly let me know I will borrow one.
> 
> Explanation
> I pass my hot through the overload to the stop button and to the selector switch.
> ...


Nickson,

Not bad, but you have a NO contact of the Reversing contactor in series with the Reversing contactor coil. Can't work.


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## Safari (Jul 9, 2013)

JRaef said:


> Nickson,
> 
> Not bad, but you have a NO contact of the Reversing contactor in series with the Reversing contactor coil. Can't work.


Yes jraef I just saw it.in my mind I thought I needed I switch there.

Now actually the circuit should be from the NO contact of timer2(T2)
It goes direct to NC contact of FWD contactor to the coil of reversing contactor.

BTWN

I have PM on an issue hope you Get to reply.


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## strikeone (Dec 23, 2013)

try this...


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## JRaef (Mar 23, 2009)

If that uses a simple hanging float switch, the contactor will be destroyed in maybe 15 minutes; there is no hysteresis in the system, meaning a difference between actions. Hit Start, Pump (compressor?) turns on, fills tank, float closes. Great. But when the float closes, the pump (compressor) reverses, ostensibly dropping tank level, float immediately opens, which reverses, which raises it again, which reverses again etc. etc.

This is why I said, in the beginning but in a different forum where he gave up trolling sooner, that it all depends on the DETAILS of the components being used. He has never responded to that, or this, line of questioning.


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