Emergency Stop Switch That Allows You To Disconnect Two Power Sources Once Enabled?

[rs14smith]

Attached is a version of what has been posted. It is generic because lacking motor data (exact motor data) it is difficult. RY1 is a standard automotive relay, RY2 would be slaved to RY1 and that is a high current relay (contactor) capable of the max current of both motors.

Ron

Oh I didn't know that was the type of schematic you were going to do. I aced doing ladder diagrams in my PLC class, the thing is, we never went over actually "where you buy the relays/contacts and how to hook them up together", so making the ladder diagram I can do in my sleep, but actually buying the right parts is where I struggle.

From the looks of your ladder diagram, you have S2 as the start button, however, RY1 and RY2 will already be energized because S1 is a normal closed button, and S2 is in parallel with RY1.

Wouldn't S2 need to be in series with RY1 if you wanted to use S2 as a "start button" for this circuit? Because right now, RY1 doesn't even care about what S2 does since it's in parallel with it. So the only thing I would be able to do with this current circuit is disconnect power by pressing S1, and if I want to enable power, I would simply let go of S1 depending on what type of switch it is. S2 isn't necessary is it?

 

[rs14smith]

I'm kinda dissapointed. I'm sure my three phase contacter would work but no one commented.
Maybe the request for an "off the shelf" version fell on deaf ears.

Mike.

Haha don't be, if this current idea doesn't work, we have a plan C, your contracter

 

[Reloadron]

I'm kinda dissapointed. I'm sure my three phase contacter would work but no one commented.
Maybe the request for an "off the shelf" version fell on deaf ears.

Mike.

Hi Mike

Actually a 3 phase contactor may work. I use them all the time for 3 phase motor starter circuits. However, there is a caveat and why I didn't suggest one. The problem being that contactors of that nature are built and designed for 3 phase inductive load motors, unfortunately the actual contacts are designed for an AC load current. That presents a problem as to the current. Everything involving what rs14smith has is sort of spread over 3 threads. He has a DC motor which originally he was powering I think off three 12 volt batteries in series, but he ran the motor off 12, 24 and 36 VDC. Initially he wanted to measure current (I think that was the first thread) and then we evolved to this thread, and also a thread on automotive relays based on my suggestion that if you want to switch higher DC currents (exceeding 25 amps) an automotive relay may be a good consideration.

Now if you look at rs14smith's recent posting history things get sort of interesting. Among the problems is I (nor anyone else I am aware of) actually knows where this DC motor came from or for that matter the full name plate data on the motor. This makes it difficult to suggest much of anything. That is why my post are so generic in nature. I am clueless as to what this motor is or where it came from. No clue as to name plate data?

Anyway, the DC current with what I can only assume an inductive load is why I did not advocate a 3 phase motor starter contactor.

Signed
Clueless in Cleveland, Ohio USA

 

[rs14smith]

No clue as to name plate data?

Well I would have provided that info but no one asked until the automotive relay thread, so I try my best to provide the info i think is needed from the start, but if more info is needed, you guys gotta let me know and I'll try to find it even if I have to take a picture of the motor.

As I stated in this thread, it's an induction motor that's in a lawn mower. I will try to find the name plate info today and get back with you all.

If you need anything else let me know, as you guys are helping me out which I highly appreciate, so whatever info I need to provide to help you help me, I will try my best to do so

 

[Reloadron]

Oh I didn't know that was the type of schematic you were going to do. I aced doing ladder diagrams in my PLC class, the thing is, we never went over actually "where you buy the relays/contacts and how to hook them up together", so making the ladder diagram I can do in my sleep, but actually buying the right parts is where I struggle.

From the looks of your ladder diagram, you have S2 as the start button, however, RY1 and RY2 will already be energized because S1 is a normal closed button, and S2 is in parallel with RY1.

Wouldn't S2 need to be in series with RY1 if you wanted to use S2 as a "start button" for this circuit? Because right now, RY1 doesn't even care about what S2 does since it's in parallel with it. So the only thing I would be able to do with this current circuit is disconnect power by pressing S1, and if I want to enable power, I would simply let go of S1 depending on what type of switch it is. S2 isn't necessary is it?

OK, as to the cartoon I made. It is a pretty standard motor start/stop circuit. The numbers for RY1 are taken directly from automotive relay numbering system. Anyway, S1 is a NC push button switch momentary type just like a simple non locking E Stop button. S2 is a NO PB switch. Pressing S2 the NO push button will bypass the NO contacts of RY1. Since S1 is NC voltage is present on one side of S2. When I press S2 it will cause RY1 to energize and pull in. The NO contacts of RY1 between #30 and #87 will close, that action will latch RY1 in an energized position even after PB S2 is released. That is a basic relay latching circuit. That same action will pull in RY2 and RY2 will remain energized since RY1 is energized and they have coils in parallel. RY2 would be a DC current contactor and the NO contacts of RY2 are now closed supplying your load. Now if I push the NC PB S1 it will momentarily open the circuit causing RY1 and subsequently RY2 to drop out. Understand?

Yes, I used basic ladder logic because that is the best way to present a simple motor start/stop circuit.

Ah, that is right. If it is a lawnmower (cordless variety) it is likely a 12 or 24 VDC motor. Please tell and a pic would be sweet.

Ron

 

[rs14smith]

OK, as to the cartoon I made. It is a pretty standard motor start/stop circuit. The numbers for RY1 are taken directly from automotive relay numbering system. Anyway, S1 is a NC push button switch momentary type just like a simple non locking E Stop button. S2 is a NO PB switch. Pressing S2 the NO push button will bypass the NO contacts of RY1. Since S1 is NC voltage is present on one side of S2. When I press S2 it will cause RY1 to energize and pull in. The NO contacts of RY1 between #30 and #87 will close, that action will latch RY1 in an energized position even after PB S2 is released. That is a basic relay latching circuit. That same action will pull in RY2 and RY2 will remain energized since RY1 is energized and they have coils in parallel. RY2 would be a DC current contactor and the NO contacts of RY2 are now closed supplying your load. Now if I push the NC PB S1 it will momentarily open the circuit causing RY1 and subsequently RY2 to drop out. Understand?

Yes, I used basic ladder logic because that is the best way to present a simple motor start/stop circuit.

Ah, that is right. If it is a lawnmower (cordless variety) it is likely a 12 or 24 VDC motor. Please tell and a pic would be sweet.

Ron

You are exactly right, this is a latching circuit, I mistaked RY1 on rung 1 for a relay instead of a contact...I must of been tired when I looked at that

Anyway, two questions:

1. What program do you use to make your ladder diagrams and is it free? Even though I'll rarely have to make these again, seems like a useful program just to have just in case.

2. It appears from the diagram both motors are attached to the same ground which wouldn't be the case in the real world application (or my particular application). Each motor is it's own separate circuit if that makes sense.

So what I would have done is, create a 3rd rung:
-on the 2nd rung have contact RY1 control motor #1
-on the 3rd rung have contact RY2 control motor #2

 

[Reloadron]

You are exactly right, this is a latching circuit, I mistaked RY1 on rung 1 for a relay instead of a contact...I must of been tired when I looked at that

Anyway, two questions:

1. What program do you use to make your ladder diagrams and is it free? Even though I'll rarely have to make these again, seems like a useful program just to have just in case.

2. It appears from the diagram both motors are attached to the same ground which wouldn't be the case in the real world application (or my particular application). Each motor is it's own separate circuit if that makes sense.

So what I would have done is, create a 3rd rung:
-on the 2nd rung have contact RY1 control motor #1
-on the 3rd rung have contact RY2 control motor #2

1. I use several programs to do schematics. That particular drawing was done using Orcad (Cadence Software). I use the full paid version at work but use a demo version at home. There is a demo version here but I think you need to download using a business email etc. Not sure as it has been awhile. It is limited but I did discover if I create parts libraries at work on the full version I can export them and drag them home on a zip drive.

2. Yes, both motors share the same common. You never mentioned isolated motors which will kick up the cost.

What exactly, in detail, are you trying to do? Maybe if you explain this in great detail we can look at the big picture.

Additionally, and I may have mentioned this earlier, if you plan to measure current on a single or both motors running that adds a few more caveats.

The contactor that would be RY2 in my drawing would be along these lines.

You really need to well define what you want to do with specifics and motor data. If this motor is off an old electric motor and battery powered it can't draw too much current or the batteries would weigh a ton.

Anyway, without much more information, we are sort of dead in the water as to a how to or ideas.

Ron

 

[rs14smith]

1. I use several programs to do schematics. That particular drawing was done using Orcad (Cadence Software). I use the full paid version at work but use a demo version at home. There is a demo version here but I think you need to download using a business email etc. Not sure as it has been awhile. It is limited but I did discover if I create parts libraries at work on the full version I can export them and drag them home on a zip drive.

2. Yes, both motors share the same common. You never mentioned isolated motors which will kick up the cost.

What exactly, in detail, are you trying to do? Maybe if you explain this in great detail we can look at the big picture.

Additionally, and I may have mentioned this earlier, if you plan to measure current on a single or both motors running that adds a few more caveats.

The contactor that would be RY2 in my drawing would be along these lines.

You really need to well define what you want to do with specifics and motor data. If this motor is off an old electric motor and battery powered it can't draw too much current or the batteries would weigh a ton.

Anyway, without much more information, we are sort of dead in the water as to a how to or ideas.

Ron

Well this entire time (in this thread) I've been stating or trying to state I'm wanting to separate two separate battery sources/circuits. Maybe I'm using the wrong termonalogy I guess...

But yes, in a sense, I have an apple and an orange which have no relation to each other.

Ex. I have only one paintball left in my paintball gun, and I need to shoot both Ron and KISS with this 1 paintball. When I shoot that paintball, it somehow hits both of them.

But mainly, if this is going to create a heavy cost, it's not that big of a deal for me, because as of right now, I already have a basic 50A switch ( for $4.00) I purchased from AutoZone that is successfully allowing me to disconnect power to the lawn mower's motor. All the switch is doing is breaking a connection which in theory seems like a simple inexpensive concept to me, but seems to become extremely complex and expensive when I would like to disconnect power to another circuit with 1 switch instead of 2 independent switches (which is still strange to me how something so simple isn't created yet lol).

But I prefer to just buy two $4.00 switches than to spit out almost $50 or more just to have this basic feature lol.

Learned something new today: The more current you have and the cooler you want your project to be, the more complex and expensive things get... hehe

Thanks for helping me to get to this conclusion about this though. And now I'm having issues with that SSR with the 24v hooked up, so since that's soo off topic to this thread, I will stop posting in this thread since I've come to a conclusion on what to do regarding the E-Stop Switch and start back with the original thread...just in case you are wondering why I switched back

 

[Reloadron]

OTAY, anytime.

Ron

 

[carbonzit]

Is it just me, or has this whole discussion taken a turn into extreme over-complication?

I mean look, for chrissakes: someone wants to turn devices on two separate circuits OFF. No PWM, no variable voltages, just kaput! on two DC voltages.

Simple. A double-pole switch (which the O.P. has already found in their Big Red Button) and a relay hefty enough to handle the current. End of story.

Seems like we're venturing into particle physics here when it's a fairly simple question of obtaining a readily-available part, say an automotive relay. Because there are certainly other such relays controlling similar loads all over the world.

If one is paranoid, then one could get a relay that's built to handle twice the current (by which I mean the maximum possible current, like the inrush of a starting motor, not the running power).

It's really not all that complicated, is it?

 

[Reloadron]

OK in mixed post we hit as high as 50 amps. Last area was 25 amps. You find a simple switch to handle 50 amps DC at 24 volts? I don't know of one. I can't find a simple SPDT switch that will handle 25 amps DC at 24 volts.

Ron

 

[carbonzit]

I suggested using a relay (which apparently the O.P. is not absolutely opposed to doing, last I heard). Certainly there are things on an automobile that draw more current than that, and certainly such relays as can handle those loads exist, no?

 

[rs14smith]

I suggested using a relay (which apparently the O.P. is not absolutely opposed to doing, last I heard). Certainly there are things on an automobile that draw more current than that, and certainly such relays as can handle those loads exist, no?

Yeah for my particular application at the moment, I have to meet a deadline, so if a lot of additional components have to be hooked up to make the basic feature work, for now I'll just stick with what I know works and what I already have (two basic on-off switches) and if possible, come back to this relay idea if I have time.

 

[carbonzit]

What "lot of additional components"? We're talking about one lousy relay here, that's all.

The only problem is finding a suitable one, and a little dedicated research ought to solve that fairly quickly.

We know such things exist, and they're not made of unobtanium. Just gotta track them down.

 

[Reloadron]

I suggested using a relay (which apparently the O.P. is not absolutely opposed to doing, last I heard). Certainly there are things on an automobile that draw more current than that, and certainly such relays as can handle those loads exist, no?

Yes, I used them in a dwg as well as starter solenoid type contactor. Automotive relays handle 40 to 70 amps and are great for high current DC motors, especially if it involves 12 volts. I think there are links in this thread as well as the automotive relay thread about all that. It's all here somewhere in dozens of post.

Ron

 

[rs14smith]

What "lot of additional components"? We're talking about one lousy relay here, that's all.

The only problem is finding a suitable one, and a little dedicated research ought to solve that fairly quickly.

We know such things exist, and they're not made of unobtanium. Just gotta track them down.

Yeah I understand that part, but as you stated, the tracking down part does take a bit of time and it's also extra money, maybe not as much as some of these other options in this thread, but I doubt it's as cheap as two switches for less than $10?. But the main point I guess I'm making is, this extra feature isn't something I have to have, it's just something I prefer. Since I already have a working solution (two regular independent switches), I'm going to go ahead and move forward to the other objectives for my project and if I have time and the money, I'll come back to this idea.

 

[KeepItSimpleStupid]

Can you not visit a junk yard and buy two external automotive starter relays for now? We never established what the power source is, but one could assume it's three 12 V batteries and 12 V could be available for controls.

The design would be a simple ON/OFF for two sources at this point with a ON/OFF mushroom type switch. Not sure if you need a NO or NC block. Sometimes you can get 2NO or 2NC or 1NC/1NO blocks. An E-stop switch can be expensive. Use a simple toggle switch until you get the right part.

I looked up a starter solenoid on a 1965 Ford Galaxy 500) which I owned and it had an external solenoid. www.rockauto.com has the part for $15.76 It's a STANDARD MOTOR PRODUCTS Part # SS581 (fender mounted). You would need two.

E-stops don't have to be momentary. Here https://www.automationdirect.com/ad..._Mushroom_Pushbuttons_-a-_Stations/E22JLB2N8B is a possible maintained E-stop.

I don't think they sell paintball guns or supplies.

 

[rs14smith]

Can you not visit a junk yard and buy two external automotive starter relays for now?

lol as stated three times now, for now I will use what I currently have that is a doable solution which is using two regular off the self $4.00 on-off switches that can handle way more current than I need them to which is great. If I have time after my entire project is completed, I will re-visit this thread and try to implement some of ideas given. This feature in this thread is basically a want, and not a need.