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

Tonyr1084

Joined Sep 24, 2015
6,452
Does this work for you? Two DPDT relays, when one is activated the other is blocked out.
View attachment 203157When the remote switch is activated the manual switch can not change the status of the relays. When the manual switch is activated then the remote switch can not change the status of the relays. The other set of contacts can control whatever you're switching.
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.
That was my first impression. However, questioning what sort of functioning wasn't completely answered. But from what I thought was being said it sounded more like the circuit posted in #24
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
That was my first impression. However, questioning what sort of functioning wasn't completely answered. But from what I thought was being said it sounded more like the circuit posted in #24
Sorry, I should have explained it better in the first place. Anyway, I think I found the solution I was looking for. Please see attached.
 

Attachments

Tonyr1084

Joined Sep 24, 2015
6,452
TC = Temp Controller
CW = Cold Water
Assuming V1, V2 & V3 are all live (24V)
TC1 & CW Inlet are ON when V1 Switch (unidentified) is active.
TC2 is ON when V3 Switch (unidentified) is active.
TC1, TC2 & CW Inlet are ON when V2 Switch (unidentified) and relay is active.

We now have another switch and one less relay. The operation of this circuit is nothing like what has been described throughout most of this thread. And we don't know which is a manual switch and which is a remote controlled switch. But as you say - you believe you found the solution you were looking for.
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
TC = Temp Controller
CW = Cold Water
Assuming V1, V2 & V3 are all live (24V)
TC1 & CW Inlet are ON when V1 Switch (unidentified) is active.
TC2 is ON when V3 Switch (unidentified) is active.
TC1, TC2 & CW Inlet are ON when V2 Switch (unidentified) and relay is active.

We now have another switch and one less relay. The operation of this circuit is nothing like what has been described throughout most of this thread. And we don't know which is a manual switch and which is a remote controlled switch. But as you say - you believe you found the solution you were looking for.
Yeah, those switches are still there. But, different configuration.

Switches on V1 and V3 (2 NO Contacts) -- Manual Switch
Switch on V2 --- Automatic Switch
 

Thread Starter

maitrey

Joined Sep 4, 2014
75
CW = Chilled Water
The water is run through a chiller giving you about 40 ~ 45 degree F water which is then run to wherever you need or want chilled water. :)

Ron
Correct, We typically use chilled water as a CW with the valve or temperature of 3-7 deg C.
 

Reloadron

Joined Jan 15, 2015
6,204
Cold water, chilled water - - - semantics.
Actually I was not trying to correct you in a bad way. No it is not semantics or about semantics. The thread starter called it out earlier as chilled water and that is an accepted industry term and frequently used. People who have worked with and around "chillers" and heat exchangers use the term daily. In this case the chilled water supply ranges between 3 ~ 7 degrees C. Anyway I was not playing a game of semantics but trying to use a correct industry term. Sorry if you took it out of context. This is an example of a large "chiller" for making chilled water in an industrial setting. You see terms like CWS meaning Chilled Water Supply or CWR Chilled Water Return on pipe lagging.

Ron
 

Tonyr1084

Joined Sep 24, 2015
6,452
Wasn't offended. Just got the impression you were being retentive. Some people have to correct everything (not saying that's you).

Back in Texas we had a big chiller tower that got struck by lightning. I remember the sound of static discharge BEFORE the flash of lightning. Then an instant and a half later the thunderous boom. Later that same day we watched the rain fall horizontally, wind whipping across the containers in the yard. Was amazed they didn't blow over. Bigger than Tractor Trailer rigs. Still surprised the wind didn't move them. Cars were moved all over the place. Lots of damage. I was parked in a protected area. Lucky me. No reports of a tornado, but that was one hell of a micro-burst (downdraft).
 

Reloadron

Joined Jan 15, 2015
6,204
Wasn't offended. Just got the impression you were being retentive. Some people have to correct everything (not saying that's you).

Back in Texas we had a big chiller tower that got struck by lightning. I remember the sound of static discharge BEFORE the flash of lightning. Then an instant and a half later the thunderous boom. Later that same day we watched the rain fall horizontally, wind whipping across the containers in the yard. Was amazed they didn't blow over. Bigger than Tractor Trailer rigs. Still surprised the wind didn't move them. Cars were moved all over the place. Lots of damage. I was parked in a protected area. Lucky me. No reports of a tornado, but that was one hell of a micro-burst (downdraft).
No, wasn't being retentive, not on purpose anyway. Yeah, we had a reclaim water tower and a few others which fortunately never took a lightening hit. We had to steam heat the water in the NE Ohio winters when we could get sub zero F. Fortunately we eventually hired a facilities engineer which was a happy day in my life. Took awhile of working with him but it went well. Facilities was not only not my forte but I had enough headaches. Yeah, you guys in Texas get some severe micro-burst. Weird stuff and I remember Delta lost a plane going into DFW due to a micro-burst. I have felt that static you mention just before a lightening strike, scares the hell out of me.

So we can now assume things like relays and lights are working as wanted?

Ron
 

Tonyr1084

Joined Sep 24, 2015
6,452
@Reloadron it would seem like the problem has been satisfactorily solved.

I didn't mention the static buildup when the tower got hit. But I DO remember when I was 17 years old, working in the mountains at a church camp - digging a trench for power, water and sewage. It was in the upper section of the campground. To keep in contact with the main lodge we had CB radio's. Being AM you could hear every static snap of lightning within maybe 20 miles.

We were digging and listening to the static and counting the seconds from static to thunder. Lightning was about 5 miles away when Joey said (not AAC Joey) "If your hair starts to stand on end you're about to get hit with lightning. I want to say it was seconds later we all started to have that fuzzy feeling. Everyone was jumping into the ditch including me. As I was dropping into the pit I SWEAR I saw lightning exit one wall of the pit and enter the other end, inches away from my face. I don't recall any heat sensation so it was probably an optical illusion. I may have caught a glimpse of lightning striking the Jeffery Pine just about 30 feet away from where we were, and had the perception that the lightning crossed in front of my face. Probably didn't. But then again, I've heard some weird stories with lightning. A house got struck and a frozen turkey in the freezer was instantly cooked. I'm sure that didn't happen - but you hear stories like that from time to time.

Remember the movie "The Great Outdoors"? The guy who was struck by lightning several times and had a grey streak of hair on top of his head. "If you see old (so-and-so) running - you better take cover."

Anyway, lightning is off topic. But seeing as how the TS has solved the problem - - - .
 
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