Hey, can anyone describe the operation and use of a stop/start/retain relay control circuit for an AC or DC machine?

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JohnA12

Joined Mar 8, 2021
8
Hey, can anyone describe the operation and use of a stop/start/retain relay control circuit for an AC or DC machine?
 

Papabravo

Joined Feb 24, 2006
16,773
Hey, can anyone describe the operation and use of a stop/start/retain relay control circuit for an AC or DC machine?
Maybe, but I'm not familiar with that specific term. Can you tell me what you think it does. It sounds a bit like what we called a 'sealing contact'. It is often used in ladder logic controls and nowadays in PLC control which has largely replaced relays, but still uses the ladder logic paradigm.

http://www.contactandcoil.com/patterns-of-ladder-logic-programming/sealed-in-coil/#:~:text=The most basic Ladder Logic Programming Pattern is,once the coil is energized: Sealed in Coil.
http://www.contactandcoil.com/patterns-of-ladder-logic-programming/startstop-circuit/
 

MisterBill2

Joined Jan 23, 2018
9,235
I am aware of Stop?Start circuits but never heard of stop/start/retain. It would be unsafe for most applications, and certainly not acceptable for almost all applications.
So please describe what that term is intended to mean.
 

MaxHeadRoom

Joined Jul 18, 2013
23,596
The typical stop start (e.g. E-stop) circuit uses a retaining contact from the relay used at the output position, this N/C contact is placed across the start P.B. ,
See typical circuits. Page #6
Edit: I see SamR has ALREADY posted the Manual.
 

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MaxHeadRoom

Joined Jul 18, 2013
23,596
Incidentally if using any of the examples in the Schneider book, they show the O/L on the R.H. side of the coil, it is now advisable practice to place it on the L.H. side for safety reasons.
.
 

MisterBill2

Joined Jan 23, 2018
9,235
Stop and start are clear, it is the "retain" that is the puzzle. And I am also aware of the Run/Jog arrangement. .
Or is it possible that the TS is referencing the sealed Start function as "Retain"???
My application of "E-Stop" buttons is that they always used a maintained position button, while a stop button was only a momentary opening of the circuit. The intent was that it would always take two steps to start after an "E-Stop" shutoff. At least two auto companies specified that for the machines and equipment that we provided.
 

MaxHeadRoom

Joined Jul 18, 2013
23,596
Stop and start are clear, it is the "retain" that is the puzzle. And I am also aware of the Run/Jog arrangement. .
Or is it possible that the TS is referencing the sealed Start function as "Retain"???
See reply in #5 , standard N.O. retaining contact across the start P.B.
I know it as Retaing contact rather than "sealed"
 

SamR

Joined Mar 19, 2019
3,484
I always heard it as the "Seal-in" relay or contact as it was typically an integral part of the motor starter and not always a separate relay. FWIW The Square D/(now)Schneider Electric is sorta the Bible for commercial/industrial wiring. Nice to keep on the shelf. Since it uses Ladder Logic it is also a nice introduction to PLC programming. Very expanded from the original one I used over 40 years ago.
 

Papabravo

Joined Feb 24, 2006
16,773
See reply in #5 , standard N.O. retaining contact across the start P.B.
I know it as Retaing contact rather than "sealed"
That is what triggered my original response, the meaning of 'sealed' and 'retained' was just too close to be coincidental. I learned ladder logic and PLC's in the Detroit area from auto industry professionals moonlighting at the local Community College (I attended the Community College two decades after getting a Master's Degree in EE). It might be a 'local' thing.
 

MaxHeadRoom

Joined Jul 18, 2013
23,596
Sealed, Latched, Retained, all depends where you got your training probably! :confused:
Fairly obvious by the descriptive similarity I would say ?
As to the Schneider manual, as mentioned, it is a bit out of date as to the inclusion of the O/L contacts on the RH side of the coil.
Now considered a no-no.
 

SamR

Joined Mar 19, 2019
3,484
Since almost all of the motors I dealt with used a Westinghouse starter which had the overloads integrated into them I never really paid any attention to where it was actually located physically. Which apparently the electricians never pointed out but then they never did pay much attention to project drawings and did what they always did before.
 

strantor

Joined Oct 3, 2010
5,632
Sealed, Latched, Retained, all depends where you got your training probably! :confused:
Fairly obvious by the descriptive similarity I would say ?
I propose bring all these different-name-for-the-same-thing...things, under one umbrella, unified by a single term. It has to be something new, so nobody gets offended that someone else's local term was chosen and theirs wasn't. I vote, eh, let's see... "bound and gagged contacts."
 

MisterBill2

Joined Jan 23, 2018
9,235
A retained contact stays in whichever state it held prior to a power interruption. So it is suitable for lighting systems. Every machine specification demands that it NOT restart after a power interruption. Hence my puzzlement. After an E-STOP shutoff, when the button was pulled back out, only the PLC processor, on systems that used a PLC or injection controller, and position indication lights were allowed to switch on. No automatic restarts were allowed.
 

strantor

Joined Oct 3, 2010
5,632
A retained contact stays in whichever state it held prior to a power interruption. So it is suitable for lighting systems. Every machine specification demands that it NOT restart after a power interruption. Hence my puzzlement. After an E-STOP shutoff, when the button was pulled back out, only the PLC processor, on systems that used a PLC or injection controller, and position indication lights were allowed to switch on. No automatic restarts were allowed.
What is this in response to? Are you arguing against the use of maintained e-stops under the premise that machinery will automatically restart if power is lost? That seems incongruous with your previous statement and leaves me puzzled.
My application of "E-Stop" buttons is that they always used a maintained position button, while a stop button was only a momentary opening of the circuit. The intent was that it would always take two steps to start after an "E-Stop" shutoff. At least two auto companies specified that for the machines and equipment that we provided.
 

MaxHeadRoom

Joined Jul 18, 2013
23,596
A retained contact stays in whichever state it held prior to a power interruption. So it is suitable for lighting systems. Every machine specification demands that it NOT restart after a power interruption. Hence my puzzlement. After an E-STOP shutoff, when the button was pulled back out, only the PLC processor, on systems that used a PLC or injection controller, and position indication lights were allowed to switch on. No automatic restarts were allowed.
You are under a misapprehension as to my meaning as outlined in the page 6 circuit I referred to in the Schneider book.
The contact in question is 'retained' when ever the contactor pulls in and retains the standard stop start circuit. Until the E-stop is pressed, in this case.
You just use different terminology which means the same thing whether sealed, latched, retained.
Just a question of semantics.
 

SamR

Joined Mar 19, 2019
3,484
Power goes off and the starter contactor is de-energized and it's auxiliary "seal-in" contacts all open. The only way to start the motor is to energize the starter coil. Which is why most motors use a starter contactor w/ pushbutton 120V control instead of a line powered HOA switch. Not using a starter contactor for motor control brings in a whole bunch of problems. Most HOAs that I used were for sump pump motors where being automatically repowered after a power loss event was required.
 

MaxHeadRoom

Joined Jul 18, 2013
23,596
For the last 40yrs or so, I have always used 24vdc control.
Especially for Solenoid valves etc.
24vdc control is pretty much standard now for industrial control systems.
 

Papabravo

Joined Feb 24, 2006
16,773
I propose bring all these different-name-for-the-same-thing...things, under one umbrella, unified by a single term. It has to be something new, so nobody gets offended that someone else's local term was chosen and theirs wasn't. I vote, eh, let's see... "bound and gagged contacts."
That sounds a bit on the kinky side. Are you sure that's a good idea?
 
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