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Motor Running Sensor ?

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aljamri

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In my home, the main water line pressure is not enough to go upto my tank ( 2 story building ). I used two tanks one down and the other on the roof, and a 1/2 Hp pump ( less than 3Amp ) in between. It will run until the upper tank full and its float closes the inlet and the pressure switch stops the pump.
all this works fine, until the upper tank start to decrease when we use water, the pump starts run/stop rapidly.

My project is to make a circuit to cut-off when the pump stops (upper tank full) wait a period of time (T) and cut-in again.

I decided to use PIC 12F629, but i do not how to tell the PIC when the pump stops. My electrical background told me to wind a conductor on the Phase conductor to get some indication (sort of CT) but still this will be a.c., regardless its amplitude, PIC will not accept it.

so any idea how to sense the current flow in a conductor ( less than 2 Ampere )?

Thanks
 
In my home, the main water line pressure is not enough to go upto my tank ( 2 story building ). I used two tanks one down and the other on the roof, and a 1/2 Hp pump ( less than 3Amp ) in between. It will run until the upper tank full and its float closes the inlet and the pressure switch stops the pump.
all this works fine, until the upper tank start to decrease when we use water, the pump starts run/stop rapidly.

My project is to make a circuit to cut-off when the pump stops (upper tank full) wait a period of time (T) and cut-in again.

I decided to use PIC 12F629, but i do not how to tell the PIC when the pump stops. My electrical background told me to wind a conductor on the Phase conductor to get some indication (sort of CT) but still this will be a.c., regardless its amplitude, PIC will not accept it.

so any idea how to sense the current flow in a conductor ( less than 2 Ampere )?

Thanks

hi,
Connect a small low voltage mains transformer across the pump motor, say 4.5Vac, rectify the output from the transformer, use a resistor and a 4.7V zener diode.
Use the PIC input to detect the +4.7V pulses or not.
 
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hi,
Connect a small low voltage mains transformer across the pump motor, say 4.5Vac, rectify the output from the transformer, use a resistor and a 4.7V zener diode.
Use the PIC input to detect the +4.7V pulses or not.

Hi Eric, thanks for your reply.

Do you mean to make it my self ? or to get a ready one? i have not come across such value, 9V is the lowest i ever seen.

Thanks
 
Hi Eric, thanks for your reply.

Do you mean to make it my self ? or to get a ready one? i have not come across such value, 9V is the lowest i ever seen.

Thanks
hi,
You can use a 9Vac transformer, you just need to increase the value of the resistor in series with the zener diode.

Do you follow OK.?

You could buy a low voltage 'dc' power supply, the type used for mobile phones. Say 4Vdc thru to 12Vdc.... use two resistors to divide the 'dc' down to +5Vdc for the PIC.

If you use this method connect a 3 pin mains socket across the motor supply cable and plug the psu into it.
 
Haha as usually very nice easy solution m8:)

-BaC
hi,
You can use a 9Vac transformer, you just need to increase the value of the resistor in series with the zener diode.

Do you follow OK.?

You could buy a low voltage 'dc' power supply, the type used for mobile phones. Say 4Vdc thru to 12Vdc.... use two resistors to divide the 'dc' down to +5Vdc for the PIC.

If you use this method connect a 3 pin mains socket across the motor supply cable and plug the psu into it.
 
More or less the zener is going to be either in a conducting state(On) or not (Off), so you would get a 1 or 0, just monitor that on a I/0 pin and problem solved:)

-BaC
 
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Oooh my goodness, that's a great, small, cheap, easy, brilliant idea. I'll do it and let you know.

Thanks
 
Oooh my goodness, that's a great, small, cheap, easy, brilliant idea. I'll do it and let you know.

Thanks


hi,
Something like this will do the job.
 

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Hi aljamri,

I wonder why you stick to idea of a timed circuit. Timing isn't very accurate if water transportation is the name of the game. (Too many unknowns about filling speed)

Assuming that the tank has to deliver small portions of water in rapid sequence the timing circuit won't do much good.

Here's my suggestion: Use the pressure switch to deactivate the pump and use a level switch for reactivation. You might use a floating level switch which can be adapted to any desired water level.

You'll require a 'C, NC, NO'-switch. (DPSP?) and connect VCC to the NC- terminal, GND to the NO-terminal. C will be connected to the PIC input. As long as the water level is within the selected limit the output will be high changing to low if the water level drops below the limit, hence reactivating the pump.

Programming the MCU you might "AND" the two switches for both functions: ON and OFF, provided the pressure switch has a logic zero output if the tank is not full.

Switching sequence in that case: (Filling) floating switch goes from low to high if water level reaches the determined height. Tank pressure switch also goes from low to high if the tank is full --> pump off.

(Consuming): Pressure switch goes from high to low --> no action taken, level switch goes from high to low --> both switches low --> pump on.

Regards

Hans
 
Yep, that is in ericgibbs fashion hehe... ;)

-BaC
Oooh my goodness, that's a great, small, cheap, easy, brilliant idea. I'll do it and let you know.

Thanks
 
I do have to say, I love the float-switch! I have used everything laying around to make them before. Including but not limited to a sponge from the kitchen and wire hanger with a N/O lever switch..haha

-BaC
**Hearing G/F complaining** "Where the heck has the kitchen sponge gone now?!"
 
If you decide to go the timed route, then this may work better.
Have the pressure switch activate a delay timer (PIC if you want) so that the motor only comes on after a set time delay. ie: Put the delay timer between the pressure switch and the motor. That way when the pressure switch turns off, indicating a full tank, the timer and motor turn off immediately. When the pressure switch turns on, the timer delays the turn on of the pump by X seconds. No need to sense the motor; the pressure sensor does it for you already.
 
Hi aljamri

This is what you want
the relais (motor) gets activated when the low level is reached it will pump to the high level is reached

when the water drains from your tank the motor will not start again unless the low (fill level is reach again)

This schematic was part of my submition for the competition but was rejected for a still not given reason

i can asure you it works as that i build it my self already and field tested it also

Robert-Jan
 

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Thats why i like this forum, you'll find many GOOD solutions for your problem. All what you have to do is to give as much as possible of related information.

Thanks for everybody, I'll go with Eric's idea because i'm in the midway, but i'll keep you suggestions for future projects, or in case this one needs modifications.

Thanks
 
hi,
Something like this will do the job.

In my junk i found 5.2 v zener diode and a celleur phone charger of 9v output, they will do the job, so you said to tailor R1 to give out 4.7v, in this case 5.2V ?

I'll use Potentiometer to adjust until get 5.2.

Is that right?

Thanks
 
In my junk i found 5.2 v zener diode and a celleur phone charger of 9v output, they will do the job, so you said to tailor R1 to give out 4.7v, in this case 5.2V ?

I'll use Potentiometer to adjust until get 5.2.

Is that right?

Thanks

hi,
Chose the resistor so that you have 10mA flowing thru the zener.

Rs= [9V - 5.2V]/0.01 = 390R.
 

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