Electric conversion

[doug293cz]

That relay circuit is so wrong! It would take several paragraphs to explain what is wrong and how to fix it. When "Start" is pressed, the voltage at pins 6 & 8 goes to zero, since the relay coil will drop the full 120V across it. Then there is no voltage going to the main power bus. And as pointed out there is no latching function. I suggest you go back to the Electric Brewery site and study the safe start circuit until you understand it.

Brew on

 

[Islandboy85]

All relay coils for the interlock relay and the main relay are 110 AC. That's why I've got the neutral bus in there. Power comes in on relay pin 7, out 8, across the start button when it is pressed, and through all the switches to the neutral bus. This energizes the interlock relay switching the poles from throws 1 and 2 to 3 and 4. Now your interlock relay is latched from pin 8-6-4 through the main power contractor coil back to the neutral bus.

 

[Islandboy85]

Push start button...
View attachment ImageUploadedByHome Brew1474515466.558868.jpg
Release start button and circuit is latched.
View attachment ImageUploadedByHome Brew1474515517.310658.jpg

 

[Islandboy85]

And if one of the HEAT or PUMP switches is already on when the start button is depressed you get the alarm.View attachment ImageUploadedByHome Brew1474515727.203260.jpg

 

[Islandboy85]

That relay circuit is so wrong! It would take several paragraphs to explain what is wrong and how to fix it. When "Start" is pressed, the voltage at pins 6 & 8 goes to zero, since the relay coil will drop the full 120V across it. Then there is no voltage going to the main power bus. And as pointed out there is no latching function. I suggest you go back to the Electric Brewery site and study the safe start circuit until you understand it.



Brew on

I have gone over the schematic in the electric brewer. He runs power through both poles to the DPDT relay and ties the two NO contacts together. He keeps the interlock relay energized through a maintained key selector switch, so there is no need for a latching circuit. I am using a momentary button, so I need the latching circuitry.
I will admit that my AC knowledge is not the best. I'm used to D.C. Since it's what I work with every day on aircraft. I know that the way the diagram I drew would work with a D.C. relay, but are you saying that I can not latch an A.C. coil relay?
Here is what I got from the electric brewer.View attachment ImageUploadedByHome Brew1474534805.580679.jpg
And the info on his relay he use http://doc.chipfind.ru/pdf/omron/mk2pns.pdf gives the relay this pinout.View attachment ImageUploadedByHome Brew1474534909.271390.jpg
So the schematic would look like this for him, but I'm still not seeing a latching circuit wired up to the relay coil. And again, he is using a maintained switch not a momentary button.View attachment ImageUploadedByHome Brew1474535012.322827.jpg

 

[doug293cz]

The problem with the way you have designed your circuit, is that when the start switch is closed, the interlock relay coil and the main power contactor coil are in series between 120V and neutral. Inductors (coils) in AC circuits act kind of like resistors in DC circuits, as far as voltage drop is concerned. So, assuming the two relays have similar inductances, the two coils in series will act as a voltage divider with about 60V across the interlock relay coil and 60V across the main power contactor coil. Neither relay will operate reliably, if at all, at half the rated coil voltage (and 1/4 the rated coil power.)

There is a similar problem with the alarm part of the circuit. The relay coil and alarm are in series, and operation is not assured.

This circuit can be redesigned to do what you want, but I won't have time to advise you until next week.

Brew on

 

[Islandboy85]

Thanks that's a big help! I appreciate the AC lesson. Looks like I'd need a three pole relay for an alarm circuit. I guess the alarm is a little over kill anyway.

 

[doug293cz]

I think Kal's circuit design is more complex than required. I think you only need one pole of the relay for a safe start interlock, so you alarm function can be done with a two pole relay. I should be able to draw something up Monday.

Brew on

 

[Islandboy85]

I think Kal's circuit design is more complex than required. I think you only need one pole of the relay for a safe start interlock, so you alarm function can be done with a two pole relay. I should be able to draw something up Monday.



Brew on

I agree. The second pole is needed if you're trying to use a momentary button.

 

[kal]

One of the reason I used a DPDT (octal) relay in the design is because relays are the most common. You don't save any money by going to a "simpler" relay since 99% of the relay parts are required in all types and simpler SPST or SPDT are just just not as common because a DPDT can always be used in its place without all of the poles or throws connected.

This is why engineers like myself who designed plant floor circuitry always standardize on parts - an electrician can pull out the defective relay and put a new one in without checking what type it is when 3 or 4 types may be available (DPST/DPDT/SPST/SPDT). When it's always the same part there is less confusion and there is no need to stock multiple relay types. For this reason too, octal (DPDT) are considerably easier to purchase because they're in high demand. They may even be cheaper because of the higher volumes produced than "simpler" relays.

Good luck!

Kal

 

[doug293cz]

Here's an easier to understand (I hope) design for a safe start circuit. The relay pin numbers will depend on what kind of relay you use. Let me know if you have any questions.



Brew on

 

[doug293cz]

I agree. The second pole is needed if you're trying to use a momentary button.

No, you don't need a second pole to use a momentary contact "Start" switch. You just have to move the start switch to the other side of the hot branch, along with the NC interlock switches in the diagram above. It then gets bypassed when the relay latches, just like the interlock switches.

Brew on

 

[Islandboy85]

No, you don't need a second pole to use a momentary contact "Start" switch. You just have to move the start switch to the other side of the hot branch, along with the NC interlock switches in the diagram above. It then gets bypassed when the relay latches, just like the interlock switches.



Brew on

Got it. Thanks for the fancy drawing. What did you use?

 

[doug293cz]

Got it. Thanks for the fancy drawing. What did you use?

I use an old (and unavailable) program called QuickCAD. It was eventually bought by Autodesk and killed because it was too good as low cost competition to other Autocad offerings.

Brew on

 

[Islandboy85]

I use an old (and unavailable) program called QuickCAD. It was eventually bought by Autodesk and killed because it was too good as low cost competition to other Autocad offerings.



Brew on

Bummer. I need to google a free/cheap program to work on my whole wiring diagram this weekend.

 

[jleiii]

Here's an easier to understand (I hope) design for a safe start circuit. The relay pin numbers will depend on what kind of relay you use. Let me know if you have any questions.

View attachment 371601

Brew on

Is the EPO switch Emergency Power Off (E-stop in OP's dwg)? If so, it will do nothing as drawn. It needs to be in the coil latch circuit, specifically between NO2 and the coils, or between start and com1/2.

On further review, there's more that looks wrong. Where does Line1 get to the coils after Start is released?? Wait, never mind I missed MAINTAINED on the start switch. This and EPO are the reverse of every control circuit I've ever seen.
EPO is Momentary and NC, and Start is Momentary and NO. Very confusing in that context. Carry on.

 

[Islandboy85]

View attachment ImageUploadedByHome Brew1475021485.378635.jpgOk, so screw the alarm. It's making my life too difficult here. How's this look?

 

[doug293cz]

Is the EPO switch Emergency Power Off (E-stop in OP's dwg)? If so, it will do nothing as drawn. It needs to be in the coil latch circuit, specifically between NO2 and the coils, or between start and com1/2.

Yes, EPO is Emergency Power Off. It is in the coil latch circuit. As shown, it will interrupt all voltage supply to the interlock relay when it is activated, thus causing the latch to be released.

On further review, there's more that looks wrong. Where does Line1 get to the coils after Start is released?? Wait, never mind I missed MAINTAINED on the start switch. This and EPO are the reverse of every control circuit I've ever seen.
EPO is Momentary and NC, and Start is Momentary and NO. Very confusing in that context. Carry on.

A proper Emergency Power Off (EPO or E-stop) switch should always be maintained action, not momentary. This is so that the equipment cannot be restarted until the emergency situation is resolved and the EPO switch is explicitly reset. A momentary action EPO could allow the equipment to be restarted, possibly from a location remote from the emergency situation, by a person unaware of the situation, before the situation has been resolved. A routine Stop switch (not an EPO) can be, and often is, a momentary action switch. The kind of start/stop latching control you are talking about is shown below.



Brew on

 

[doug293cz]

View attachment 371667Ok, so screw the alarm. It's making my life too difficult here. How's this look?

This circuit will work, but I don't see how it is any simpler than the one I provided that does allow for the alarm you desire.

Brew on

 

[Islandboy85]

Yes, EPO is Emergency Power Off. It is in the coil latch circuit. As shown, it will interrupt all voltage supply to the interlock relay when it is activated, thus causing the latch to be released.







A proper Emergency Power Off (EPO or E-stop) switch should always be maintained action, not momentary. This is so that the equipment cannot be restarted until the emergency situation is resolved and the EPO switch is explicitly reset. A momentary action EPO could allow the equipment to be restarted, possibly from a location remote from the emergency situation, by a person unaware of the situation, before the situation has been resolved. A routine Stop switch (not an EPO) can be, and often is, a momentary action switch. The kind of start/stop latching control you are talking about is shown below.



View attachment 371698



Brew on

The EPO is a maintained mushroom button... push off, pull in. It is in series with the momentary push button (your second action) to trigger the interlock relay. If you lose power or whatever it will de-energize the interlock relay which will prevent the main power contractor closing.

 

[Islandboy85]

This circuit will work, but I don't see how it is any simpler than the one I provided that does allow for the alarm you desire.



Brew on

I have a momentary button to energize the coil. Yours has a maintained switch in it like the key switch the electric brewer uses.
I think for it to work with the momentary button the power to the two relay poles has to come from between the EPO and start button.

 

[doug293cz]

The EPO is a maintained mushroom button... push off, pull in. It is in series with the momentary push button (your second action) to trigger the interlock relay. If you lose power or whatever it will de-energize the interlock relay which will prevent the main power contractor closing.

There are no momentary action switches in my design.

Brew on

 

[doug293cz]

I have a momentary button to energize the coil. Yours has a maintained switch in it like the key switch the electric brewer uses.
I think for it to work with the momentary button the power to the two relay poles has to come from between the EPO and start button.

Sorry, for some reason I got the impression you were going to use a maintained action start switch.

If you want to use a momentary action start switch, just move the branch connection on the right of my start switch to the left of the start switch.

Brew on

 

[Islandboy85]

Sorry, for some reason I got the impression you were going to use a maintained action start switch.



If you want to use a momentary action start switch, just move the branch connection on the right of my start switch to the left of the start switch.



Brew on

Ha! It's cool. We will get this hammered out eventually. I think that'll work well. The alarm would sound as soon as you close the EPO, Sonia think I'll leave that out.
Karl, thanks for the explanation on the relay. I didn't see that post earlier. For some reason the app didn't load it. Makes a lot of sense to have as few oddball parts as possible in the equipment.
Well boys, I think we are making some progress, but it's bedtime for me now. Hopefully I get time to finish putting in the outlets In the enclosure tomorrow. I need to get that done before the weekend since my honey do list is to put pulls in all our cabinets in the house.
Oh? One more thing. I've found some info on minimum bend radius for wires at their terminating end, but nothing about the routing between. I've also seen some manufactures that state to rout it so that the wires not damaged... duh. Some charts say to use 8x the conductor diameter. What's the standard?

 

[doug293cz]

Ha! It's cool. We will get this hammered out eventually. I think that'll work well. The alarm would sound as soon as you close the EPO, Sonia think I'll leave that out.
Karl, thanks for the explanation on the relay. I didn't see that post earlier. For some reason the app didn't load it. Makes a lot of sense to have as few oddball parts as possible in the equipment.
Well boys, I think we are making some progress, but it's bedtime for me now. Hopefully I get time to finish putting in the outlets In the enclosure tomorrow. I need to get that done before the weekend since my honey do list is to put pulls in all our cabinets in the house.
Oh? One more thing. I've found some info on minimum bend radius for wires at their terminating end, but nothing about the routing between. I've also seen some manufactures that state to rout it so that the wires not damaged... duh. Some charts say to use 8x the conductor diameter. What's the standard?

You are correct. The alarm wouldn't function if desired if my circuit was modified to use momentary action start switch.

Brew on

 

[Islandboy85]

You are correct. The alarm wouldn't function if desired if my circuit was modified to use momentary action start switch.



Brew on

Yeah, I think I'll just have to figure out to go look at my switches if the power doesn't come on. At this point I need to just get this thing built and brew again. I can always mod it later when I've got by kegs filled up again. [emoji481] I really appreciate you all helping out.

 

[Islandboy85]

Well, I was going to get a stainless HERMS coil, but a friend hooked me up with 50' of 1/2" L copper tubing. He drinks my beer all the time, so it'll work out well for him anyway. Saved me a hundred or so bucks too.

 

[Islandboy85]

Well, after much delay I’ve picked back up on this project. Was a little down for a while after my little brewmeowster (cat) ran away. He used to help with the build. Got the holes punched for the heating elements and pumps. The heating elements still need opened up with a flap wheel since I didn’t have a big enough punch. View attachment IMG_4613.jpg
Turns out the end of my power cord I measured to the strain reliefs/cable gland was larger than the end I popped off for running into the enclosure. So... that’s gona get pumped full of sealant to keep it in place. A little disappointed in that, but it’ll work.

 

[BrunDog]

U need a mechanical lock on the cable which ensures it won’t move. One trip walking by the cable could put enough tension on it to pull conductors out of terminals or worse, just loosen them. That would be bad with live conductors.

 

[Islandboy85]

U need a mechanical lock on the cable which ensures it won’t move. One trip walking by the cable could put enough tension on it to pull conductors out of terminals or worse, just loosen them. That would be bad with live conductors.

The sealant I’ll be using is way beyond RTV. We use it on aircraft at work. So much of it goes to waste. When it is fully cured it usually takes a hammer and plastic scrapers or a knife to cut it.