Relay circuit with reset button and buzzer

[cyrusthevirus]

I have a tank filled with water. If the water level rises below a float switch, I want to turn off a power strip. If the water rises above a float switch, I want to turn off a power strip. If the power gets turned off to the power strip, I want to have a buzzer sound and require a button to be pressed to reset the system. The float switches can be either NC or NO. Does this have to be two different circuits? Will I need a small UPS so I do not have to reset everything when the power goes out?

The power stip is currently connected to a standard 15A 120V circuit.

Thanks for the help.

 

[KeepItSimpleStupid]

My drawing skills arelimited at the moment, so bear with me.

I see a couple of additions: Buzzer silence (on/off) ,buzzer test(PB) and a 9V battery.The buzzer test just verifies that the 9Vbattery is good. It would just beused to sound the buzzer when the power is out.

A 3PDT relay with a 120 VAC coil can do this for you. I'll call the contacts: a,b,c and NO for norm open, NC for NC and C for common.

The buzzer part: Take the 9V battery in series with NC(a) and C(a) the buzzer silence switchand back to the negative of the battery. Put the buzzer test C and NC contact across the relay in the same place as the NC(a) and C(a)

So, when the power is out, the battery supplies power for the buzzer and you can turn it off and test the battery.

Take one of the other contacts NO(b) and C(b) and put it in series with the black lead of the power. You might want to put a cord and and a socket on a separate box. This switces power to the outlet strip.

Route always on line power (black) to C(c) and NO(c) to one end of the coil. Connect white to the other side of the coil. Now,if wecan get the relay to close,power stays applied to the relay.

Wire the NC contact of a switch (OFF), if desired, in series with the above, Pushing this button will open the circuit nd drop out the relay. Also put your float switches here. What you want is the contact to open when you want the relay to drop out.

Now wire a NO pushbutton across the NO(c) and C(c) above. This provides a means of initally closing the relay.

The relay will automatically drop out with a power failure.

I placed one of these (just a relay and a button) inan outlet strip. I connected a modem to it and a phoone line. If the modem didn't anser the phone, I knew a power fail occured at work.

 

[cyrusthevirus]

I attached a file with what I believe is the pinout for a 3PDT. Using the write up below, what would be connected to each number?

 

[KeepItSimpleStupid]

It is. The coil is pins A & B. There is no polarity for an AC coil.

Think of the coil pulling the horizontal bar toward the other pointy arrow. So the arrows are either the NC or NO contacts. 7,8 and 9 will be the common pins. Since 7 is shown touching #1 and #7 is common to both of the arrows, it's a common terminal to #1 and #4. Since #1 is touching the arrow,that contact will be a NC or Normally Closed one. Pin#4 is the NO or Normally Open contact. #1, #4 and #7 make up the equlivelent of an SPDT or single pole double throw switch.

You can arbitrarily label the colums as a, b and c so #1 is NC(a); #4 is NO(a) and #7 is C(a) etc.

 

[cyrusthevirus]

Okay so I started putting a diagram together, but I am not sure where the float switches go.

Here are the specs on the float switch:
Temperature: -10 ~ +90°C
Contact rating: 50W
Max Switching Voltage: <=220VAC
Min Breakdown Voltage: 600VDC
Max Switching Current: 2.5A
Max Contact Resistance: 100mΩ
Specific Gravity: .8

 

[cyrusthevirus]

Anyone have any additional advice?

 

[KeepItSimpleStupid]

I'm gonna have to send my new laptop for repair really soon. My other one is on the fritz too. It's the holidays and I also have a funeral to go to. Sorry about that. I was out nearly all day today shopping & errands.

You need a push button similar to the one you've drawn between pins 9 and 6 to arm the relay. Once you push it, the relay will stay engaged.

You need an on/off switch to act as a buzzer silence, if you want it in series with the battery.

You need to insert your float switches into the B to 6 wire. When you momentarily open this circuit, the relay will drop out.

 

[cyrusthevirus]

I'm gonna have to send my new laptop for repair really soon. My other one is on the fritz too. It's the holidays and I also have a funeral to go to. Sorry about that. I was out nearly all day today shopping & errands.

Sorry. I have had some bad experiences where someone was helping me and then nothing. I appreciate you taking the time.

You need to insert your float switches into the B to 6 wire. When you momentarily open this circuit, the relay will drop out.

Do I insert them in series or parallel? I assume they should be NC?

 

[KeepItSimpleStupid]

I can't quite answer that.

You said drop out when Float 1 is below level 1 and another when float 2 is above level 2.
What this means is when when the level is correct, the floats should be closed. This may not be the NC contacts.
So, when the levels are correct, place the closed contacts (based on when the level is correct) from the floats in series.

Make sense?

 

[cyrusthevirus]

I can't quite answer that.

You said drop out when Float 1 is below level 1 and another when float 2 is above level 2.

Correct

What this means is when when the level is correct, the floats should be closed. This may not be the NC contacts.
So, when the levels are correct, place the closed contacts (based on when the level is correct) from the floats in series.
Make sense?

The point would be that if the fluid level is correct, the float "switch" would be off. By not passing any current the relay drop out. If I ran them in parallel then they would need to rely on each other to drop out the relay, however in series they run independent of each other. Correct?

 

[KeepItSimpleStupid]

Ok, another comminications issue. Float switches can be Normally open (alarm applications), Normally closed (overflow/drop aout applicationsor both (An SPDT switch).

Lets suppose you had an SPDT float or one NC and 1 NO contact. Open means unactivated at rest. Closed with full water like in a toilet tank.
In This case:
If no water, then both switches would be open.
If water at above the first level, but below the second, then bottom would be closed and top would be open.
If above the second switch, then both switches would be closed.

So,this scenero, creates a problem. In the upper switch, you would need to use the NC contact then.
Below first level, bottom would be open.
Between levels top and bottom would be closed
Above top level, top would be open

So, if they are wired in series properly, then either switch (above top) or (below bottom) would open the circuit.

If your switches are the wrong type you can use another relay to invert one of the outputs.

This page: https://www.electro-tech-online.com/custompdfs/2010/12/an-mc-004.pdf kinda shows what you have, but not exactly.
You can replace the 24 VDC power with 120 VAC and remove two phases and it's almost what you have.
The || and the |/| are separate Normally open and Normally closed contacts. In his word, they don't share a common point.

You can think of the |/| contact 95 & 96 as where your float switches go. Two of them. e.g 95----| |----| /|-----96. the first being the level 1 switch (below level 1) and the second being the level 2 switch (Open greater than level #2)

 

[cyrusthevirus]

Okay I understand. The float I am using is an SPDT float depending on how it is mounted it will be NC or NO. If you do not mind, I am going to put together a parts list, can you check it over?

Thanks again for everything.

 

[KeepItSimpleStupid]

I'll see what I can do. I lost my reply again because of a pop up and don't have time right now to finish. But basically it concerned the construction technique. My way is an industrial technique where nearly all parts are reuseable. Generally,it's expensive. It's an accepted way control panels are wired.

 

[KeepItSimpleStupid]

Continuing:

Lots of things come back and bite you because you don't realize what you need or why you need it. Take for example wire: There is copper, solid and various stranding varieties and colors. You might need 6", but need to buy 100' for $20 or so, so that's $60 for 3 colors. That's just for ground, hot and neutral. Now let's say you use 3 different colors for the NC and NO and C circuits of the switch. Later, when you start to troubleshoot, it would be so much easier than if the entire circuit was wired in only yellow wire. Yep, I sad to troubleshoot such a mess.

When I did control panel wiring, I used 18 AWG with a smaller number of strands like 7, so they were less flexible. Solid wire doesn't work well with crimp connectors.

IDEC is my favorite relay manufacturer because of how clearly and where the wiring diagram is. They are available with "check buttons" (allows mechanical activation) and LED's (Coil energized). These can prove invaluable when troubleshooting too. Sockets/connectors can be useful,but are SOMETIMES a source of reliability issues.

A connector in this case could offer "strain relief" capabilities and the ability to switch floats easily, but there would be a tendency to make the floats not directly interchangeable to avoid putting the system together wrong. I also tended to use a larger connector with VERY easily replaced pins, thus these were reuseable for other projects. Cord diameters were accomodated with different shells.

My construction technique comes from how telephones are usually wired in a large office. Each room gets its own terminal and risers and laterals get their own terminals. You then cross-connect within the wiring closet.

I digress: In a home, what I would probably do which is not a standard practice. In a home there may be few lines, a burgler alarm RJ31z jack, and Ethernet with lots of locations, I'd probably use CAT5E or CAT6 cables to corresponding RJ45 jacks at a central point.
I'd create one panel with 4 lines bussed which would distribute the lines. So you would have, room jacks(2), ethernet switch and a panel of 4 bussed lines. I would do any line transformations in clearly marked patch cables.

One of the typical arrangements is FAX, DSL, Business, Home and alarm. Alarm could be a PERS (Personal Emergency Response) or Intrusion or a combination. A PERS panel might be installed in a bedroom. So, things can get messy real fast. While the house I live in was wired some 50 years ago and 90% quad wiring, non-home runs and 4-prong and modular connections in the same locations I had to make some changes such that I have "A pristine DSL" install per the telco technician. Tracking down static when there are 12 or more paralleled connections can be tough. I had water in a cable and cobwebs in a surface mount jack(same run) after a flood and rain. The jacket took months to dry out once identified. I still don't like about 6 wires on the original stud, but at least I have a disconnect point. Which phone is off the hook is another problem.

Anyway back to wiring. The DIN rail construction technique combined with what I might call telco wiring methods works very well. The DIN rail allows easy changes and the terminals are about $2.00 each. In this technique, each input/output would get its own set of terminals. Even with what you have, you end up creating terminals very quickly: Power in, power out, bottom float, top float, alarm silence, battery, arm, disarm, (run pump manually), (float status). the last two I just added for fun as they could be additions. I might try to accomodate these changes at a later date.

You get the idea as to how simple things can become very easy to troubleshoot, modular and reuseable. One or many plays a role too.

Here is a sample: DIN Rail Terminal Blocks

 

[cyrusthevirus]

Wow, thanks for all of the information. I already have several different colors of 18AWG wire from other projects. I am comfortable with my parts list except for two simple items. The reset buttons and the on-off switch. The on-off only needs to be rated for 9V, what about the push buttons? Can you recommend a part number for reference?

 

[KeepItSimpleStupid]

This is a nice switch for buzzer test: 40-1665-01: JUDCO MANUFACTURING: Electromechanical

This is a nice switch for for the buzzer silence: Digi-Key - CKN1128-ND (Manufacturer - 7201K2ZQE)

You can't rely on the pic, but you have to pull the lever to change the position of the switch, so it's a pull and move, so it can't be accidently moved to another position. I used a DPDT in case you want to use a light when bypassed.


These switches Catalog 128 | Newark.com get out of hand in prices,but they are used extensively to make industrial control panels. You can see some of the possibilites. You have rotary switches and contact blocks. The contactblocs have NO contacts and NC contacts. There are not SPDT type switches. You have to roll your own. You have illuminated switches as well. Sometimes 120 VAC is not available.

I've used the IDEC LA3L series extensively Allied Electronics - Catalog for control type stuff. I used the rectangular lamps a lot because you can take off the lens and relabel it (print on transparency film). With these it's best not to solder, but too use crimp faston connectors. They don't have a high current rating and you can only get the lamps/LEDs in 24 VAC/DC.

As for an ON/OFF switch, I'd consider an ON/OFF rocker with separate connections to the lamp. Generally the problem with that is the lamp dies if it's neon.

If I were bullet proofing this design, I might use a larger rotary switch for power and use the smaller series stuff for arm/disarm with corresponding lights, but now you have the light power supply causing issues. Using a 4PDT switch would solve that and you would need a 24 VAC supply. The relays could easily be changed to operate on 24 VAC as well. That's just some ideas.

I did a modify of a panel once and used these really cool SPDT relays that would fit in like a 1/8" wide area of the DIN rail. They had an activation light and screw terminals and would operate on 24 VAC or 24VDC with no change in the relay p/n. They were like $20 each with a current rating of about 3A.

 

[cyrusthevirus]

Okay here is what I believe to be my parts list unless you see a problem.

(2) push buttons

(1) relay

(1) DIN socket

(1) buzzer

(1) 9V lead

(1) On/Off switch for buzzer
(I liked your suggestion for the switch, however I would be worried that I would have to teach someone watching my tank on how to turn it off.)

(2) Float Switches

Thanks againg for your help.

 

[KeepItSimpleStupid]

The buzzer comes from the UK and has a stiff handling charge. I don't know where you are.

The float switch instructions are not clear. My guess is you turn it upside down to go from NO to NC ,but it's just a guess.

The push button is only suitable for the battery test. It's NO and DC rated. You need an AC rated Normally Closed (NC) PB for the other button.
There are differences between AC and DC switch contacts.

There are missing parts like the case etc

 

[cyrusthevirus]

See I knew there was a reason I posted them.

How about these
(1) Buzzer

(1) Push button

 

[KeepItSimpleStupid]

See I knew there was a reason I posted them.

How about these
(1) Buzzer

Nope: 28 VDC - You'll need three 9V batteries in series. There are battery holders available too even for 9V. Some are just clips.

(1) Push button

OK