Happy HolidaySs Giveaway - Winners Re-Re-Re-Re-Drawn - 24 hours to Claim!

Get your HBT Growlers, Shirts and Membership before the Rush!


Home Brew Forums > Home Brewing Beer > Electric Brewing > Selector switch that automatically turns off when power's cut?
Reply
 
LinkBack Thread Tools
Old 10-28-2010, 03:01 PM   #1
kal
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
kal's Avatar
Recipes 
 
Join Date: Nov 2006
Location: Ottawa, Canada
Posts: 2,184
Liked 220 Times on 151 Posts
Likes Given: 6

Default Selector switch that automatically turns off when power's cut?

I don't know if this sort of switch exists, it may be just me not using the right terminology when searching.

I have a 3-way maintained ELEMENT SELECT switch on my control panel today like this:



It's used to select which of the two elements (BOIL or HLT) receives power. In the center position both elements are off. This ensures that only one element may be on at once (a design choice I made).

I'm looking for a 3 position maintained switch that springs back to center OFF position if power is cut.

In other words, the two outside maintained positions are somehow maintained but if power to the panel is cut, the switch instead behaves like a spring return switch and springs back to the center OFF position. I imagine to do this, when the switch is turned to either ON position it would have to energize some sort of holding (electromagnet?) circuit that holds the switch in the on position.

Why do I want this?

Today whenever I first turn on the panel power, I have to always *first* make sure that this switch is in the off position. While this is fine for my use, from an ergonomic/process standpoint that's not quite right: When power's cut to the panel, this switch should always reset itself to off for safety reasons. Some sort of interlock is required to make sure someone doesn't trip up. This would stop having an element turn on when then panel is first turned on. (Especially useful for someone who doesn't use ULWD elements which will pop if not turned on while in water).

Anyone heard of something like this?

Kal

kal is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 03:27 PM   #2
CodeRage
Death by Magumba!
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
CodeRage's Avatar
Recipes 
 
Join Date: Aug 2007
Location: Melbourne, Fl
Posts: 2,254
Liked 33 Times on 18 Posts
Likes Given: 5

Default

Kal,
I haven't seen what you're looking for, if it does exist it is pretty specialized which would mean a big price tag if you could find it.

What I would do is put in a 3 position return to center switch. To select an element you turn the switch in that direction and a contact on the switch sets a latch for that contact. It also will open another contact to break the latch circuit for the other element. After you let go of the switch it will return to the center position. You can use a panel light to indicate which element is currently selected. The only problem is you would have to add a second push button to break both latches to turn the element off (break both lathes) during a brew session.

Alternatively, you could add a momentary button to enable the elements. You hit the Enable button and it sets a latch allowing control power to the selector switch. (You can use the same maintained selector switch as is) Once you remove power from the control panel the latch will drop out so the next time it powers up the elements will be disabled until the enable button is pressed. You may want to add a disable button so you can manually drop out the enable latch without having to cycle power to the panel. It's not necessary considering you're not taking any functionality away from the current design.
Personally I like the second option best.

I can provide a drawing if this interests you. If you have a schematic of it's current configuration that would be helpful too.

__________________
Brutus 20e build | Electrical Primer for Brewers | Auber SYL-2362A2 PID Install & Config
So as I am walking out the door this morning I think to my self:
"self, going to work on Monday is like knowing you're going to get kicked in the nuts. You just don't know when or by who"
CodeRage is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 03:52 PM   #3
short_mark
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jan 2009
Location: CT River Valley - where 2 meet 1
Posts: 10
Default

Kal

I don't think you can do it with a maintained switch but....

Using a three position momentary switch, you could add a DPDT relay behind the switch for each position. The control voltage from your key switch then feeds power to the momentary switch and when you toggle in either direction the voltage fires the relay and latches it on the second contact.

To turn either element off, you could change the yellow indicator lights on the panel to indicator switches that have a NC contact block. Then when you press the button it interrupts the control voltage going to the relay latch and opens the contact.

Electrically each element would look something like this:

Key switch>>>>NO momentary switch>>>>NO relay contact>>>>element PID
Key switch>>>>NC indicator switch>>>>NO relay contact>>>>relay coil

__________________

If I wanted it to be simple, I'd buy the beer

short_mark is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 04:11 PM   #4
kal
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
kal's Avatar
Recipes 
 
Join Date: Nov 2006
Location: Ottawa, Canada
Posts: 2,184
Liked 220 Times on 151 Posts
Likes Given: 6

Default

Doh! Of course! That makes perfect sense guys. Us a pushbutton or momentary contact switch of some sort to latch a relay.

CodeRage: I have drawings here: http://www.theelectricbrewery.com/co...part-2?page=13

This is probably the one you want:





Kal

kal is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 04:30 PM   #5
CodeRage
Death by Magumba!
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
CodeRage's Avatar
Recipes 
 
Join Date: Aug 2007
Location: Melbourne, Fl
Posts: 2,254
Liked 33 Times on 18 Posts
Likes Given: 5

Default

Yeah, you just need a DPDT 120V octal relay and a momentary PB.

Wire one side of the momentary to 120V, then the output to the relay coil, then Neutral on the other side of the coil.
Next run 120V to one side of a NO contact, then the other side of the NO contact to 120V side of the relays own coil.

Last wire the second NO contact on the relay to break the connection between the selector switch and 'hot bus'.

__________________
Brutus 20e build | Electrical Primer for Brewers | Auber SYL-2362A2 PID Install & Config
So as I am walking out the door this morning I think to my self:
"self, going to work on Monday is like knowing you're going to get kicked in the nuts. You just don't know when or by who"
CodeRage is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 04:31 PM   #6
JayInJersey
Feedback Score: 0 reviews
Recipes 
 
Join Date: May 2009
Location: New Jersey
Posts: 600
Liked 1 Times on 1 Posts
Likes Given: 2

Default

I like the enable button idea. Or is it possible to have the panel not power up if the selector switch isn't in the OFF position?

Kind of like you can't turn on your car if it is in Drive...


I guess you would need a push button to start it or a key that had an Off-On-Ignition selection.

__________________
JayInJersey is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 04:47 PM   #7
CodeRage
Death by Magumba!
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
 
CodeRage's Avatar
Recipes 
 
Join Date: Aug 2007
Location: Melbourne, Fl
Posts: 2,254
Liked 33 Times on 18 Posts
Likes Given: 5

Default

Here's a quick ladder sketch.

enable-circuit.jpg  
__________________
Brutus 20e build | Electrical Primer for Brewers | Auber SYL-2362A2 PID Install & Config
So as I am walking out the door this morning I think to my self:
"self, going to work on Monday is like knowing you're going to get kicked in the nuts. You just don't know when or by who"
CodeRage is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 05:45 PM   #8
kal
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
kal's Avatar
Recipes 
 
Join Date: Nov 2006
Location: Ottawa, Canada
Posts: 2,184
Liked 220 Times on 151 Posts
Likes Given: 6

Default

Thanks for the sketch CodeRage!

One thing I'm trying to avoid is any changes to the panel in terms of external switches/controls. I'll just leave it the way it is if it comes to that.

JayInJersey has a really intersting idea: Not have the panel power up if the 3-way selector switch isn't in the OFF position.

This is actually really easy to do: I can add two NC contactors to the back of the 3-way switch. They will BOTH be closed when the switch is off. The wire the POWER ON/OFF SWITCH through those two contactors first in series. The POWER ON/OFF SWITCH won't get any power then unless the ELEMENT SELECT switch is OFF.

The catch however is that as soon as you turn the ELEMENT SELECT to either side, you cut power to the panel.

Gotta think about this some more....

Kal

__________________
TheElectricBrewery.com: A step by step guide to building your own electric brewery
My basement/bar/brewery build 2.0
kal is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 05:46 PM   #9
JayInJersey
Feedback Score: 0 reviews
Recipes 
 
Join Date: May 2009
Location: New Jersey
Posts: 600
Liked 1 Times on 1 Posts
Likes Given: 2

Default

CR/Kal

Couldn't you instead add that Enable push button to the key lock (meaning you need to turn key then press button) and wire it so it could only be enabled when both Pumps and the 3 Selector are in the OFF position?

That way you could protect your whole setup when you turn it on in case someone flipped a switch you didn't notice between sessions.


Added bonus to that being on Kal's CP design you could add that button right under the key as there is some free space there.


Just thinking out loud here.

__________________
JayInJersey is offline
 
Reply With Quote Quick reply to this message
Old 10-28-2010, 05:47 PM   #10
JayInJersey
Feedback Score: 0 reviews
Recipes 
 
Join Date: May 2009
Location: New Jersey
Posts: 600
Liked 1 Times on 1 Posts
Likes Given: 2

Default

Wow I must have posted that like seconds after yours...

__________________
Hazard Brewing
JayInJersey is offline
 
Reply With Quote Quick reply to this message
Reply



Quick Reply
Message:
Options
Thread Tools




Newest Threads

LATEST SPONSOR DEALS