Need help with 24vac controls

[fridaynightfan]

I have a 220v well pump relay that has a 24vac input that activates it.

I have a control panel with a 24vac output that connects to this relay for control.

I want to add a 2nd control panel to this system. I cant find any info from the manufacturer of the control panels if there is an internal relay on the 24vac output for the well pump.

To be safe, should I diode - isolate both control panels from one another. So that when one turns on, it doesnt send AC to the other?

If so, what type of diodes should I use ? I am very familiar with using DC in automobiles, but not so much in using diodes with AC.

I went to a local electronics shop and was given some diodes, but when I insert them into the circuit, only 5 vac comes out of the diode.

Thanks in advance for any assistance.

 

[crutschow]

You can't use diodes to isolate AC.

You could use a relay to open the circuit from the second panel when the first panel is energized.

 

[KeepItSimpleStupid]

What does the second panel do?

Do you want the 1st and second panel to turn on the pump?

Under what conditions does the pump turn off with two panels?

 

[fridaynightfan]

Thanks for your responses. The second panel is just like the first..it sends a 24vac out to activate a pump relay.

To clarify, everything in the system works fine, both control panels work, etc. I just havent connected them both at the same time for fear of frying the one that isnt on, if that makes sense,


So, when either of the control panels arent on, the pump is off. If using a relay to isolate is the way to go, can someone post a diagram or list of what goes where? I am familiar with Bosch relays, just havent used them with ac. Just knowing what goes to 85, 86, etc would help.

 

[MikeMl]

Bosch relays are for automotive use (12Vdc). They cannot be used on AC. If you end up using a relay {or two), they will have to be 24VAC relays.

What comes to mind is a "three-way" switch like in a hall light. There would be an added toggle switch on both control panels. The position of the toggle switch would determine who has control, panelA or PanelB. The selection of which panel has control can be done from either panel. When PanelA is selected, PanelB does nothing and vise versa.

 

[crutschow]

The easiest may be just to add another power relay in parallel to power the pump motor, controlled by the second panel. That way if either one or the other, or both relays are energized, the pump will be on. This connection will give no interaction problem between the panels.

 

[carbonzit]

Right, like this:

**broken link removed**

Both relays operate on 24 VAC. Contacts, of course, must be rated for the load (pump motor).

 

[KeepItSimpleStupid]

Well, I disagree somewhat. For the US, you have to break both legs of the 240, this is where locale helps.

generally, I like only one contactor in a circuit, but...

1. You can just parallel the contacts going to the motor. i.e. disconnect one set internally and parallel across the other set.

2. You can decide who is going to supply 24 VAC power or create a new source. Have the pump utilize a single contactor for the pump. A pilot duty 24 VAC coil and contact is used to energize one contactor using one power source for the contactor (pick one).
Contactor can be external.

Many things can influence the best way. I'm assuming it's not 3 phase and there is nothing downstream of the contactor except the pump.

Not sure what your trying to accomplish.

 

[carbonzit]

Well, I disagree somewhat. For the US, you have to break both legs of the 240, this is where locale helps.

Well, that's trivially easy to fix: use DPST relay contacts instead of SPST, to switch both legs of the 240 volt line. Surprised you didn't suggest that (especially considering your moniker).

 

[crutschow]

Well, I disagree somewhat. For the US, you have to break both legs of the 240, this is where locale helps.

So just use a DPDT or DPST relay instead of a SPDT.

Edit: You beat me by 3 minutes, carbonzit.

 

[KeepItSimpleStupid]

I know what messed me up; The relay contacts are in the wrong place based on the schematic symbol for a relay I'm used to.

 

[carbonzit]

I know what messed me up; The relay contacts are in the wrong place based on the schematic symbol for a relay I'm used to.

So you're blaming my drawing for your confusion, eh?

There must be, what?, a couple dozen ways to draw a relay symbol. I thought mine was not half bad.

 

[fridaynightfan]

Thanks for the responses. I want to clarify - I want to use an exisiting pump start relay that is installed (and working). I am wanting to install an additional relay on the input (turn on) leads only - to isolate them. I have found an Omron LY2-AC24 general purpose cube type 24vac relay which looks like it would work in this application. Can anyone suggest a wiring diagram for this relay? I cant seem to locate one online.

Many thanks!

 

[KeepItSimpleStupid]

Yipes. That took a while. The datasheet is here: https://www.electro-tech-online.com/custompdfs/2011/04/090600_OMRON_LYdatasheet_J002-E3-10.pdf

You will need a socket.

Do you have a wiring diagram of the controller?

 

[crutschow]

Do you have access to the 24VAC from the controllers?

 

[KeepItSimpleStupid]

Very good question crutschow.

You either have to:
1) Pick one to steal 24 VAC from
2) Create your own 24 VAC using either an energy limiting transformer or fused primary/secondary. HVAC transformers are common for this application. I personally like energy limiting transformers.

We're running somewhat blind on the details of the controller and don't even have a model #.
The datasheet migh be tough to decifer. Yell if you have any questions.

 

[fridaynightfan]

The controller is a Rain Bird ESP-8TM. There is access to the 24v power supply lead at the controller itself. Thanks for the advice so far. I have the data sheet for the Omron relay, but it is confusing as to how to wire.

I also wonder if the Rain Bird controller has an internal relay on the MVO output (trigger output for the pump relay that I am feeding) which would prevent it from being damaged when off if another controller was attached to the same output.

Since I cannot know for sure, I think it is best to install a relay on each of the two controller's outputs that are attached to the pump start relay.

 

[crutschow]

The controller is a Rain Bird ESP-8TM. There is access to the 24v power supply lead at the controller itself. Thanks for the advice so far. I have the data sheet for the Omron relay, but it is confusing as to how to wire.

Since I cannot know for sure, I think it is best to install a relay on each of the two controller's outputs that are attached to the pump start relay.

You should provide the 24AC power for the contacts from only one of the 24VAC supplies to avoid any problems.

For example, connect the 24VAC power from one of the controllers to one wiper on each relay (Pin 5) in parallel.

Connect the NO outputs (Pin 3) of each relay in parallel to the motor pump start relay.

Connect the 28VAC controller output signals to their respective relay coils (Pins 7).

Pin 8 goes to the respective 28VAC controller power return.

 

[fridaynightfan]

Carl,

Perfect! That's exactly what I needed.

 

[fridaynightfan]

You should provide the 24AC power for the contacts from only one of the 24VAC supplies to avoid any problems.

For example, connect the 24VAC power from one of the controllers to one wiper on each relay (Pin 5) in parallel.

Connect the NO outputs (Pin 3) of each relay in parallel to the motor pump start relay.

Connect the 28VAC controller output signals to their respective relay coils (Pins 7).

Pin 8 goes to the respective 28VAC controller power return.

The pump start relay is looking for 2 wires from the controller. Above you say to connect it to pin 3, where should the common wire output connect? Does it matter, can it just connect to the 24vac powere supply, since it isnt switched?