How to detect if the pump on ?

Thread Starter

ohmTronics

Joined Jun 23, 2020
2
Hi All,

I need to design a system which detecting if the water pump on or not and if it on and still on for a specific time say 30 min i need to turn led on and disconnect the 220v ac from the pump.

a 220v ac always connected to the pump and its work only when there is a flow of water .

Any suggestion help me to build such system ?

Regards
 

ronsimpson

Joined Oct 7, 2019
726
Do you want to get out the soldering iron and build something? or get time delay relays and do a "house wiring" project?
This relay is pricey but with a socket a electrician can build complicated time delay functions. They come in two common modes. When you power it on it will delay then turn on. OR When you power it on it will turn on and delay out then turn off.
1592953584718.png
Thinking: If the input to the relay was across the motor so when the motor is on the relay timer is on...… and the relay was a delay to on type, then after 30 minutes the contacts close. This will turn on a light.

What to do about turning off the motor. This relay is only 10A and 1/2 horse power. It might not be strong to power the pump. This relay could drive a bigger relay that powers the motor.

Just some thoughts. Good luck RonS.
 

dendad

Joined Feb 20, 2016
3,569
A small current transformer driving a bridge rectifier and LED with series resistor works well to detect the pump running.
I built quite a number of these for a customer a few years ago.
But does the pump start with a pressure switch?
Do you need to detect the water flow?
Are you wanting to turn the pump off if there is no water?
It may be an idea to define the full operation a bit better.
 

Thread Starter

ohmTronics

Joined Jun 23, 2020
2
Thank you for reply

The pump provided with an automatic system to turn on and off the pump depending if any Faucet at home opens and then the water flow from the tank.

220v ac always connected to the pump and the automatic system internaly control pump on and off so i cant detect if the pump on and off by detecting the presence of 220v .

What i need when the pump turned on for a certain time say 30 min i need to turn led on indicates the pump works for 30 min continuosly and i need to disconnect the 220v feeding the pump.
When i reset the system a 220 v connect feeding the pump again.

What i think now to use acs712 current sensor with tiny controller to do that but if there is another way better than what i think or without using any microcontroller.

Regards
 

drc_567

Joined Dec 29, 2008
855
A frequently used pump activation method utilizes an air pressure tank that incorporates a pressure sensitive trigger connected in such a manner so as to turn the pump motor on.:
air pressure system,
... Another way of getting pressurized water to the faucets. Factors might include reliability, convenience, or the costs involved.
 

dendad

Joined Feb 20, 2016
3,569
As I mentioned in post #3,
A small current transformer driving a bridge rectifier and LED with series resistor works well to detect the pump running.
This way, there is no electrical connection needed. Just one power wire feeding the pump is fed through the transformer.
If you want accurate current readings, this may help.. But I think it is more complicated that you need.
https://circuitdigest.com/electronic-circuits/ac-current-measurement-circuit-using-current-transformer-and-arduino

Or this simpler one...
http://henrysbench.capnfatz.com/henrys-bench/arduino-current-measurements/ta12-100-arduino-ac-current-sensor-tutorial/

Have you used Arduinos at all?

I was going to post a picture of the things I made, but at the moment, I cannot find where I've put them.
 

MisterBill2

Joined Jan 23, 2018
6,354
It seems that what the TS is really seeking is an automatic shutoff for the event of either a leak, a stuck valve, or a tap left on. Probably the pump system already includes a pressure switch to turn it on when any flow is demanded. In that case, a time relay connected across the pump motor, or a flow switch in the discharge line, can trigger a second relay to remove pump power after 30 minutes. The same contact can also switch on an indicator ,
An alternative approach would be to have the time relay trip a GFCI device that would remove power from the motor until it was reset. That could be simpler and cost less.
 
The real problem isn't detecting if the faucet is left on (flow meter with digital output/mechanical flow switch) but if its leaking. The amount of flow from a leaky fitting/tap would be moot at best. Would that even be a concern? Is this for an inline booster pump? If so, then maybe being unable to detect such minute changes in water would be a good thing.
 

crutschow

Joined Mar 14, 2008
25,132
You could use a current-sense relay, such as below, triggering a time-delay, such as in post #2.
The time-delay relay would need to drive a latching-relay, so that the motor stays off after the current stops and the current-relay opens (unless you can find a latching time-delay relay, perhaps like this).

Of course, if you are able to wire some electroncs with a couple ICs, then the cost could be lower.

1593089358511.png
 

MisterBill2

Joined Jan 23, 2018
6,354
It seems that possibly the TS can have access to the motor terminals and that is cheaper than the current sensor. And the idea for using the GFCI to lock it off is probably cheaper than any relay rated for the motor current. Plus, it is already a recognized safety device.
 

MaxHeadRoom

Joined Jul 18, 2013
20,927
I don't see the motor/pump technology/type, if an ordinary radial impeller sump pump style, the current will drop as the back pressure increases.
Highest when maximum flow.
Max.
 

MisterBill2

Joined Jan 23, 2018
6,354
The request was to detect the pump running, we all just presume that sensing flow is better. I think that it might be better, but detecting it running is certainly much simpler.
 
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