DOL starter and switches

munga42 · May 3, 2011

Hi,

I have a Dol starter which i would like to use for my single phase irrigation pump. The Coil on the contactor is 240v. there are 3 lines in L1 L2 L3. It is connected to a 17 - 25 amp overload. I know that I have to link the wires together some how, T1 to L3?? There is a start button on the top but its not connected to anything, 13 & 14 N/O?

The idea would be to link in a pressure switch to stop pump when the travel sprinkler comes to the end of its run. Also within the water tank I would like a float switch that would cutout the pump when the water is low. I would like a solenoid water valve to be activated when the float switch stops the pump and allows fill up of tank then shut off when the float switch starts the pump again when the tank is full. Its only in my head at the moment and not sure on how to carry all this out!! Any help would be appreciated.

Jim

geoffa · May 3, 2011

not being funny but if you don't know what the N/O contact is for maybe you should get an electrician who knows what he's doing to carry out the work for you.
are you a qualified electrician?

munga42 · May 3, 2011

I'm just asking for advice on my setup,. I haven't done much with contactors before so advice was all I was looking for Geoffa. I do know what N/O is. The question mark was to emphasize that I need help in wiring the contactor correctly and not N/O?

Jim

johnboy6083 · May 3, 2011

i know exactly what you want, but i cant translate it onto paper. IMO, you dont want a sol valve, they can be more hassle than they are worth. a ball cock is more than adequate. you can buy sump pumps with float switches for your pump protection.

with single phase loads on 3 pole contactors its considered good practice to use all of the poles. you do this by looping the live from t1 to l2 and then you take your outgoing feed from t2, your neutral goes straight through l3 and t3.

for the pressure switch, you may want to consider using a small relay that interupts the coil to the main contactor.
as i cannot see exactly what gear you have ect, its difficult for me to help any more, and also im crap at translating what im thinking into words that are legible to any normal man! lol

munga42 · May 3, 2011

Thanks. The reason i'm looking at using solenoid valve is cos i'm linking more than one tank together, therefore I need the solenoid to let water in to all tanks. The float switch would only be on one tank but as they would fill at the same rate. Not sure how I go about getting them to work together As one closes, the other opens and also starting pump . Is it best practice to use a relay or can I link them in series in to the contactor. Therefore kinda making the start button obsolite. Does that make sense?

Jim

johnboy6083 · May 3, 2011

can you draw a small shematic of your system? the i and others may be able to suggest something. how many pumps are there? are you using multiple tanks to feed one pump? how big is your water main? ect

munga42 · May 3, 2011

I have one 3KW vertical multistage pump with a return flow pipe to the tanks , one pressure switch on the outlet side, 5 IBC tanks linked together with 1 float switch and looking to get solenoid valve for tanks top up. The travel sprinkler I am using has a auto cut off when it has finished its run, that's where the pressure switch comes in. Thanks all for your help.

Jim

Marvo · May 3, 2011

Consider it as three separate electrical systems. First you have a high liquid level system to control the water going into the reservoir tanks, this could be a solenoid with probes/float switch or a good old ball float valve like in a toilet. Second you have a low level safety system to stop your pump from dry running when the tanks become empty. This could also be probes and liquid level control or a float switch which interrupts the power to the contactor coil. Third you have a pressure switch or prescontrol on the discharge side of the pump to swicth it on when there's demand. Now all you need to do is figure out the best way to integrate the three systems. I'd offer a suggestion but I'm confused about the line in your OP where you say 'when the travel sprinkler comes to the end of its run.'

munga42 · May 3, 2011

The travel sprinkler i have has a mechanical cut off valve on the sprinkler which shuts off the water flow to the sprinkler head. The pump needs to have the pressure switch as the flow from the pump to the sprinkler is still on until in reaches the desired pressure to cut out.
I did toy with the idea of ball floats but i would have to install in each tank which adds to the cost. 1 solenoid i thought might be the answer but if I go and use the ball float solution I guess it makes the system alot easier.

Jim

Marvo · May 3, 2011

Cant you just link your tanks together below ground with a 50mm LDPE pipe and a few insert fittings? That way the tankswill find their own level and act as a single larger tank.

munga42 · May 3, 2011

still left with how to stop the water top up though

Marvo · May 3, 2011

Here's a schematic. The two probe sets obviously have associated liquid level controllers.

[ElectriciansForums.net] DOL starter and switches

johnboy6083 · May 4, 2011

The idea of balance lines to link your tanks is a good one, but in the past weve had problems sizing this line. We found that the balance lines had to be oversized so that the last tank in the line is filing up at the same rate as the one receiving the water main.
As marvo said liquid level controllers could be used, and are relatively easy to wire. You would need one for your water make up and one for your pump protection. I can't remember the ones that we used, so I can't link to one. I don't get your pressure switch? We would need to know how your sprinkler system is set up to know that. I've used rainbird in the past, and that was straight forward.

munga42 · May 4, 2011

I am trying to use what I have available to me with out spending to much. I have the float switch, the pressure switch,the pump , 5 ibc tanks and starter. The pressure switch is being used to protect pump, as the pressure rises after sprinkler has finished its run the pressure switch will cut in at say 8 bar. When the travel sprinkler has been set up for another run, the pressure switch will cut out and so on. It sounds a bit crude the setup. but with a solenoid valve on the water inlet I thought might be the answer? The flaw with ballcocks is the tanks will fill up constantly as the level drops where as with a sole valve they would almost empty before refill.

johnboy6083 · May 4, 2011

that isnt a flaw with the ball cocks, its probably their best feature. also they rarely fail.. in your idea of using a sol valve, your tanks will havwe to be sized to take the full amount of water t5hat the system will use. with a ball cock, as the water will constantly be topping up, you have more capacity.

DOL starter and switches

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