Design Interlock for two operations (Manual Switch and Automatic Switch)

Thread Starter

maitrey

Joined Sep 4, 2014
75
Not sure what you are looking for with the lamps but if RY1 is about temp controller 1 place the lamp across the relay 1 coil, place the second lamp across RY2 coil. Then each lamp will illuminate when its respective relay is energized. I don't have the software you are making your schematics with or I would have used it. Not sure what CW inlet is about?

Ron
Lamps are nothing but my outputs and have to activate/deavtivate at the same time. CW inlet is chilled water inlet point (in this case it is a lamp). I know all of this is quite confusing.
 

Reloadron

Joined Jan 15, 2015
6,206
Lamps are nothing but my outputs and have to activate/deavtivate at the same time. CW inlet is chilled water inlet point (in this case it is a lamp). I know all of this is quite confusing.
OK and actually not all that confusing I spent an entire career with temperature controls, chilled water supplied and all sorts of similar controls. :)

Yopu have everything and it's just a matter of getting things wired correctly.

Ron
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
OK and actually not all that confusing I spent an entire career with temperature controls, chilled water supplied and all sorts of similar controls. :)

Yopu have everything and it's just a matter of getting things wired correctly.

Ron
Ron - I agree. TBH- I have never spent this much time on one problem.

There is a (3-way) manual switch on our equipment where COLD-OFF-HOT operation is controlled. There are two wires (+2 and +3) coming from each module. I am looking to add remote start/stop for both COLD and HOT operation. (Right now all this discussion is on COLD part only) My theory is if I give 24 VDC to this two wire then I should be able to implement remote start/stop. (Supply for this contact blocks are coming from E-stop)

The problem is operator won't know if somebody initiated remote start/stop or not and if he accidently turns the switch manually then there would be some electrical issues. Bottom line, I couldn't imaplement all 4 cases as of now!! :(

Please see attached. Hope it makes much more sense. :) Control bus is nothing but separation as I need two (+3) and (+5) wires but can't use jumper.
1585781854406.png
 

djsfantasi

Joined Apr 11, 2010
7,919
Thanks Ron,

The problem is to connect 24 VDC to Lamps as If I connect it from first relay, it won't work for second relay and vice versa. Spent too much time on this ;(
View attachment 203185
What part of:

DON’T CHANGE ANYTHING ON THE SECOND SET OF CONTACTS ON BOTH RELAYS.

...didn’t you understand? In Post#33, you had solved the problem on switching the lights from both relays.

I’m sure you’ll be glad to know I won’t be able to help that much. It’s hard to help someone who blindly makes changes without understanding them. Don’t worry, there’s a lot of people who have that problem. But it’s totally impossible to help someone who can’t listen, EVEN TO INSTRUCTIONS IN ALL CAPS TO ENSURE THAT THEY ARE FOLLOWED.
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
What part of:

DON’T CHANGE ANYTHING ON THE SECOND SET OF CONTACTS ON BOTH RELAYS.

...didn’t you understand? In Post#33, you had solved the problem on switching the lights from both relays.

I’m sure you’ll be glad to know I won’t be able to help that much. It’s hard to help someone who blindly makes changes without understanding them. Don’t worry, there’s a lot of people who have that problem. But it’s totally impossible to help someone who can’t listen, EVEN TO INSTRUCTIONS IN ALL CAPS TO ENSURE THAT THEY ARE FOLLOWED.
Appreciate all your help. I am sorry if I am being pain in the ass. But I believe there is some misunderstanding. Below are the cases I want to achieve and even if I combine 17,23 and 32 How am I gonna energized lamps since the manual switch is OFF itself.

SW1 OFF --- SW2 ON---LAMPS ON (In this case, SW2 voltage is coming from SW1 and if SW1 is closed then I won't be able to energized Lamps here)
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
What happens if you connect the lamp before the manual switch?
Then it always be ON. I should have explained it better sorry.

In the actual circuit, V1 supply is coming from E-stop NC contact meaning it is always active. If I connect lamp before SW1 then it will always be ON regardless of manual SW position. Hope this answers your question.
 

djsfantasi

Joined Apr 11, 2010
7,919
Then it always be ON. I should have explained it better sorry.

In the actual circuit, V1 supply is coming from E-stop NC contact meaning it is always active. If I connect lamp before SW1 then it will always be ON regardless of manual SW position. Hope this answers your question.
Are you willing to bet?

I bet that it will only be on when you switch one of the relays..,
 

djsfantasi

Joined Apr 11, 2010
7,919
Here is a modified diagram. Manually trace the connection from the bottom of the lamps to its connections. It has two.

When you move the other lamp wire before the switch, the lights CANNOT be lit. If you trace the bottom wire as I suggested, you’ll see why.
71D87AA9-A820-4A5E-8D2F-D6E6AFD00525.jpeg
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
Here is a modified diagram. Manually trace the connection from the bottom of the lamps to its connections. It has two.

When you move the other lamp wire before the switch, the lights CANNOT be lit. If you trace the bottom wire as I suggested, you’ll see why.
View attachment 203202
This is correct. Although when I simulate this circuit, after first cycle both relay contacts are latched and cannot turn off the lights even after turning off the main switch. May be it has to do with relay type I am using (Latching relay DPDT).
1585796446443.png
 

Tonyr1084

Joined Sep 24, 2015
6,455
There is an issue in the above circuit. It will work for (1) and (3) case but not for (2). The reason is when we turn ON the remote switch it is not getting any power as Manual switch is OFF. Also the power which is connected to (C) of first relay has to be coming from manual switch nad not for additional source.
I thought you said each source has to be its own source. I left those lines open to whatever source you wanted to use so that you could connect them to a single source or multiple sources. The engineering design was up to you.
Can't you just use the power going to the manual switch for the source?
I believe he said he couldn't because something was "Always on" - if I remember correctly; and I don't want to search through the entire thread to discover whether that was said or not. It's merely the premises I was going on.
Ron,

I am stuck with the actual connections though. I get the logic behind it. Any canges I can make to the following circuit to make it work?

The tricky part here is to implement when both SW is ON at the same time --- LAMP must be OFF.
View attachment 203183
In this configuration the lights would only be on when the switch with V1 was on. If it is off then nothing will work.
This is correct. Although when I simulate this circuit, after first cycle both relay contacts are latched and cannot turn off the lights even after turning off the main switch. May be it has to do with relay type I am using (Latching relay DPDT).
View attachment 203206
Isn't this the circuit I drew up? OK, a little bit different, but in the end, one relay set can establish the status of the lamps and the other relay can change it to the opposite operation. Also, if your software is saying it doesn't work - it's possible something may be wrong with your software.

The drawing I gave you, my final version, the relays were set up as a simple three way light; you know, the kind where you can turn the lights on from the bottom of the stairs then turn them off at the top - and vice versa. Someone asked why I had one relay sourcing and the next sinking. In my final version that shouldn't be the case. As I said, it was set up as a three way setup. I also said you could do away with the first relay and simply use a SPDT switch (Single Pole Double Throw). You don't even need that first relay. The relay connected to the remote - IF the remote only has a single HIGH / LOW output then you need the relay. But if the remote has a built in NC and NO terminals along with the C then you don't need the other relay either.

There've been so many iterations of this drawing I'm totally confused now. At this point I think I've done all I can and can add nothing more. IF we understand how you want this to operate then you've gotten several confirmations on what works. If we (meaning "me") don't understand something - I just don't know where to go from here.

Good luck with your project.

Stay healthy.
 
Last edited:

Thread Starter

maitrey

Joined Sep 4, 2014
75
I thought you said each source has to be its own source. I left those lines open to whatever source you wanted to use so that you could connect them to a single source or multiple sources. The engineering design was up to you.
I believe he said he couldn't because something was "Always on" - if I remember correctly; and I don't want to search through the entire thread to discover whether that was said or not. It's merely the premises I was going on.
In this configuration the lights would only be on when the switch with V1 was on. If it is off then nothing will work.
Isn't this the circuit I drew up? OK, a little bit different, but in the end, one relay set can establish the status of the lamps and the other relay can change it to the opposite operation.

There've been so many iterations of this drawing I'm totally confused now. At this point I think I've done all I can and can add nothing more. IF we understand how you want this to operate then you've gotten several confirmations on what works. If we (meaning "me") don't understand something - I just don't know where to go from here.

Good luck with your project.

Stay healthy.
I think I definitely got much understanding of how should I implement this circuit several ways.

Apprecaite all your effort and time. Thank you so much for helping me out. :) Stay safe.
 

djsfantasi

Joined Apr 11, 2010
7,919
You’re using latching relays? Latching relays? You’re using latching relays?

I can’t remember seeing that you're using latching relays.

This circuit and all of the variants we’ve tossed around are based on regular relays. Latching relays are completely different animals.

Do you have regular relays? If this is just a simulation at this point, don’t use latching relays.
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
You’re using latching relays? Latching relays? You’re using latching relays?

I can’t remember seeing that your using latching relays.

This circuit and all of the variants we’ve tossed around are based on regular relays. Latching relays are completely different animals.

Do you have regular relays? If this is just a simulation at this point, don’t use latching relays.
I know. I will be using regular relays only but couldn't find one in my software.
 

Tonyr1084

Joined Sep 24, 2015
6,455
I know. I will be using regular relays only but couldn't find one in my software.
Then that's why your sim isn't working. When both relays are on (Latched) then the lights can only be off. With regular relays, one on and the other off - the lights light up. When both relays are in the same state then the lights are off. When in opposition (one on and one off) the lights come on.
 

Tonyr1084

Joined Sep 24, 2015
6,455
And with my circuit you don't need DPDT relays. Again, you don't even need the first relay (RL1). It can be replaced with a SPDT switch.

AH! I'm done.

Best wishes.
 

djsfantasi

Joined Apr 11, 2010
7,919
And with my circuit you don't need DPDT relays. Again, you don't even need the first relay (RL1). It can be replaced with a SPDT switch.

AH! I'm done.

Best wishes.
@Tonyr1084

The circuit you presented in post #24?

Refer to the switching/switches/relays as a “control”. The requirements state that if the “manual control” is operated, then the “remote control” is disabled. And if the remote control is operated, the other control is disabled.

The circuit in post #24 toggles the load every time either control is switched. In other words, if one control is operated, the other will NOT be disabled. The other control will still have an effect.
 
Top