irrigation pump control switch

[gamb00ler]

I have a Rain Bird irrigation controller to open and close the sprinkler valves using 24v AC solenoids.

 

The irrigation controller can also control the pump using a 24v AC pump control switch that will close/open the 230V circuit and start/stop the pump.

 

My Lazada/AliExpress search skills are inadequate to find me the right kind of switch.

Can somebody find one or suggest the best search terms?

 

I'm in CM so maybe a seller at Kham Thiang Garden market may have what I want.

 

 

[VocalNeal]

Just a 24V relay with enough capacity to run the pump. We just need to know the amp rating of your pump.

[gamb00ler]

Thanks, I didn't know that a simple relay is all I really need.

My electrical knowledge is basically zero.

 

So would something like this would suffice?

https://www.lazada.co.th/products/30a-t9as1d22-12-1240vac-30244-i4702370558.html?spm=a2o4m.searchlist.list.26.4466708adoxnho

 

[Artisi]

Go to your nearest local pump shop and ask. 

[Crossy]

If your Rainbird is putting out 24V AC then you need a relay with an AC coil, what's the Amps / HP rating of your pump?

 

[gamb00ler]

1 minute ago, Crossy said:

If your Rainbird is putting out 24V AC then you need a relay with an AC coil, what's the Amps / HP rating of your pump?

 

Looks like 8A.

[Crossy]

A quick scan of Lazada shows suitable AC coil relays are like hen's teeth, and 24V AC contactors are $$$.

 

So, how about an AC to AC solid state relay?

 

First one I found is 80V input ???? 

[VocalNeal]

43 minutes ago, gamb00ler said:

Thanks, I didn't know that a simple relay is all I really need.

My electrical knowledge is basically zero.

 

So would something like this would suffice?

https://www.lazada.co.th/products/30a-t9as1d22-12-1240vac-30244-i4702370558.html?spm=a2o4m.searchlist.list.26.4466708adoxnho

 

No you need something that uses 24V to power and that will switch 220VAC at whatever your pump draws. Do you really need 30A?

 

This will work @ 179Baht switches 10A https://shopee.co.th/Relay-ของแท้-รีเลย์-MK2P-I-24V-220V-12V-48V-110-AC-DC-ซ็อกเก็ต-i.75734101.8033237404?sp_atk=0545d935-91d2-4a0d-8f1c-a276fef1d71b&xptdk=0545d935-91d2-4a0d-8f1c-a276fef1d71b 

Select 24v and xxx+xxxx

 

Your pump is 8A but I don't know what the inrush will be our friend above will know. 

[VocalNeal]

This will definitely work 24vdc input switched load 220v40A 

https://www.lazada.co.th/products/solid-state-relay-ssr-40dassr-60dassr-80da-40a-60a-80a-100a-ssr-40da-60da80da100da-i3965981256-s15339882837.html?

 

139 Baht

 

 

It has been a slow day????

[gamb00ler]

1 hour ago, VocalNeal said:

This will definitely work 24vdc input switched load 220v40A 

https://www.lazada.co.th/products/solid-state-relay-ssr-40dassr-60dassr-80da-40a-60a-80a-100a-ssr-40da-60da80da100da-i3965981256-s15339882837.html?

 

139 Baht

 

 

It has been a slow day????

????

Thanks for all the effort.  That relay seems to check all the boxes.

????

[treetops]

6 hours ago, gamb00ler said:

Thanks for all the effort.  That relay seems to check all the boxes.

Except your OP indicates the controller gives out 24V AC to switch the pump.  That relay requires a DC input.

[gamb00ler]

On 7/25/2023 at 12:32 AM, treetops said:

Except your OP indicates the controller gives out 24V AC to switch the pump.  That relay requires a DC input.

you're right, thanks.  For a novice like me, it's easy to miss a crucial detail.

[sometimewoodworker]

Just a FWIW I came across these they may be exactly what is needed

[Yellowtail]

You could use a 24V relay to operate a 223-volt contactor/motor-starter. 

[gamb00ler]

Thanks to Google Voice its easy for me to call US based customer support #'s.  Rain Bird provides very good phone support and they confirmed that the following old style relay would do the trick.  But, I probably should go for the solid state version @sometimewoodworker showed.

 

PS: I just checked those solid state relays on AliExpress and it appears the minimum control voltage they require is 70V but Rain Bird controller supplies only 24V AC.  I presume when the seller say "Input" they are referring to the voltage that would come from the irrigation controller.

 

[sometimewoodworker]

Use a 24V DC relay to switch 24v AC then use the 24V AC to switch a 250V AC source using  SSR then a high power 250v AC contactor to switch your load

[gamb00ler]

2 minutes ago, sometimewoodworker said:

Use a 24V DC relay to switch 24v AC then use the 24V AC to switch a 250V AC source using  SSR then a high power 250v AC contactor to switch your load

That's starting to sound somewhat like a Rube Goldberg creation.  I think the old style coil relay for 142 ฿ is sounding better and better.

[sometimewoodworker]

19 minutes ago, gamb00ler said:

That's starting to sound somewhat like a Rube Goldberg creation.  I think the old style coil relay for 142 ฿ is sounding better and better.

That shows that you have no idea of the details of the setup and reasoning behind it.

DC needs significantly beefed up contacts. So switching high load DC is an expensive option.

low voltage DC requires less insulation.

AC switching requires lower rated contacts

Switching higher power requires higher rated insulation.

As you have found low voltage DC relays only switch low voltage (unless custom designed)

You need sealed switches as water vapour/high humidity will destroy DC devices quickly 

 

You can custom order a 24V DC relay to switch high current 250V AC

But for a tenth of the cost, a tenth of the time and higher reliability you can use 3 relays setup as I suggest and probably never bother with them again.

 

 

[gamb00ler]

21 minutes ago, sometimewoodworker said:

That shows that you have no idea of the details of the setup and reasoning behind it.

DC needs significantly beefed up contacts. So switching high load DC is an expensive option.

low voltage DC requires less insulation.

AC switching requires lower rated contacts

Switching higher power requires higher rated insulation.

As you have found low voltage DC relays only switch low voltage (unless custom designed)

You need sealed switches as water vapour/high humidity will destroy DC devices quickly 

 

You can custom order a 24V DC relay to switch high current 250V AC

But for a tenth of the cost, a tenth of the time and higher reliability you can use 3 relays setup as I suggest and probably never bother with them again.

 

 

DC is not involved in my setup at all.  The controller uses 24VAC to open/close the relay that controls 230VAC flow to the pump.

[Fruit Trader]

Solid state relays for reactive loads like a 1.5HP motor should be chosen carefully. Not all switching methods are suitable.

Low price fake Chinese Fotek brand (zero cross point) solid state relays are famous for containing underated low quality componemts unable to handle specified currents. A search for cheap Chinese solid state relays will soon reveal why they are so cheap.

 

 

A reliable and common solution for Sprinkler controllers like Rainbird and Hunter is to interface with a pump contactor using a small 24V ac relay.

Below shows irrigation control we built for a local well installation. The  sprinkler controller calls a 24V AC relay which in turn energises the 220V AC pump contactor to supply a feed pump.

 

 

 

 

 

 

Example of a off the shelf sprinkler to pump interface.

 

 

[sometimewoodworker]

44 minutes ago, gamb00ler said:

DC is not involved in my setup at all.  The controller uses 24VAC to open/close the relay that controls 230VAC flow to the pump.

My mistake. That eliminates the possibility of using any available solid state relays since they are all 70v~80v minimum.

A quality version of an unsealed relay is 

 

 

[gamb00ler]

4 minutes ago, Fruit Trader said:

The  sprinkler controller calls a 24V AC relay which in turn energises the 220V AC pump contactor to supply a feed pump.

It seems like you are telling me that I cannot rely upon the relay I showed in an earlier post to complete the circuit from PEA power to the pump.  The pump I'm using draws 8 Amps and they rate that relay at 10 Amps.  

 

It seems that the price of 142฿ is rather low. 

 

[sometimewoodworker]

1 hour ago, gamb00ler said:

It seems like you are telling me that I cannot rely upon the relay I showed in an earlier post to complete the circuit from PEA power to the pump.  The pump I'm using draws 8 Amps and they rate that relay at 10 Amps.  

 

It seems that the price of 142฿ is rather low. 

 

The relay will certainly work. The problem is that it will certainly fail and the time before failure is rather unpredictable because the contact points are small and so it isn’t suitable for prolonged use. The MTB is almost certainly not hours, unlikely to be days, probably not weeks, but after that uncertain.

[gamb00ler]

31 minutes ago, sometimewoodworker said:

The relay will certainly work. The problem is that it will certainly fail and the time before failure is rather unpredictable because the contact points are small and so it isn’t suitable for prolonged use. The MTB is almost certainly not hours, unlikely to be days, probably not weeks, but after that uncertain.

The typical use will be once a day or less in the rainy season and perhaps up to twice a day in the dry season in Chiang Mai.  Average use will certainly be less than twice per day.

 

When the relay fails, will the pump go off, stay on or stay in whatever state it was in before failure?

[Fruit Trader]

3 hours ago, gamb00ler said:

It seems like you are telling me that I cannot rely upon the relay I showed in an earlier post to complete the circuit from PEA power to the pump.  The pump I'm using draws 8 Amps and they rate that relay at 10 Amps.  

 

It seems that the price of 142฿ is rather low. 

 

The 8 pin 24V ac relay shown earlier will do the job if only operated one time each day.

 

As for the cheap solid state relays, they do not employ the ideal electronic switching method for inductive loads. Very likely it would fail in the on state which is probably not ideal or even introduce a high resistance path and cook itself to death.
 

[sometimewoodworker]

1 hour ago, gamb00ler said:

When the relay fails, will the pump go off, stay on or stay in whatever state it was in before failure?

 

29 minutes ago, Fruit Trader said:

The 8 pin 24V ac relay shown earlier will do the job if only operated one time each day.

As I mentioned the time to fail is unpredictable as is the failure mode. The contacts could weld themselves shut, they could equally erode until the make no connection, they could attract enough ants that they can’t close. 

[Yellowtail]

2 hours ago, Fruit Trader said:

The 8 pin 24V ac relay shown earlier will do the job if only operated one time each day.

 

As for the cheap solid state relays, they do not employ the ideal electronic switching method for inductive loads. Very likely it would fail in the on state which is probably not ideal or even introduce a high resistance path and cook itself to death.
 

I think using a 24VAC relay to actuate a 230VAC contactor/motor-starter as you described previously is a much better option. 

 

Does the pump motor have overload protection? If not, I think a starter is the way to go. 

 

Components are inexpensive enough that it makes little sense to cheap out on it. 

[gamb00ler]

@VocalNeal has been assisting me on this matter as well.  He kindly identified an appropriate contactor to use with the 24V AC relay I was considering.  While looking at his suggestion I think I found a 24VAC contactor that will do the entire job of controlling the pump.  Hopefully those knowledgeable will decide it is a reliable single component solution.

 

This link is from a US based shop but I'm sure I can get the exact item in Thailand.

 

https://shop1.us.mitsubishielectric.com/products/S-N11 AC24V

[Yellowtail]

On 8/5/2023 at 4:15 PM, gamb00ler said:

@VocalNeal has been assisting me on this matter as well.  He kindly identified an appropriate contactor to use with the 24V AC relay I was considering.  While looking at his suggestion I think I found a 24VAC contactor that will do the entire job of controlling the pump.  Hopefully those knowledgeable will decide it is a reliable single component solution.

 

This link is from a US based shop but I'm sure I can get the exact item in Thailand.

 

https://shop1.us.mitsubishielectric.com/products/S-N11 AC24V

Looks like it should work...

 

MODEL:S-N11 MAGNETIC CONTACTORS AC-1=Ith 20A VOLTS:AC24V AC48V AC110V AC220V AC380V 50/60Hz | Lazada.co.th