we live in the country and have a 220v well pump, trying to design a duty cycle monitor to shut off power if well pump is running to much, water leaks or dry well can cause pump to run continuously and get a 1000$ electric bill, so either need a duty cycle monitor, or whole hose amperage monitor
Moderator edit: thread title. I can only assume it was incorrect.
What do you mean by duty cycle ? You are not trying to supply a PWM signal on the pump I hope ?
With a Current Transformer (CT) you can monitor is the pump is running without making contact to the 220V.
http://openenergymonitor.org/emon/buildingblocks/ct-sensors-interface
But that is not enough, there schould be a fail-safe backup.
To control the pump, you can use a relay or SSR (solid state relay).
Replace your well pump pressure switch with one that has a low pressure cutout (home improvement stores have them). When the pump pressure goes below the low pressure set point the normal pressure switch is blocked shutting off the pump until the cutout is reset.
Commercial well pump protectors are standard, readily available and designed to tolerate harsh outdoor environments. They would be much more reliable (and much safer) than something you might cobble together with an Arduino.
It is not so easy to detect low water conditions, which will burn up a pump and could cost you a lot more than that $1000 electric bill!
I have one of these and it has worked for 20 years: Page not Found | Franklin Electric
midmofarmer:
we live in the country and have a 220v well pump, trying to design a duty cycle monitor to shut off power if well pump is running to much, water leaks or dry well can cause pump to run continuously and get a 1000$ electric bill, so either need a duty cycle monitor, or whole hose amperage monitor
Please search eBay for "wattmeter S0". They will count the amount of electric energy that had been used and the S0 interface provides count pulses that are a worldwide standard.
S0-Wattmeters with "DIN rail mount" can be mounted by any electrician easily.
Perhaps do a Google search for "arduino s0 pulse counter" on projects how to count the wattmeter pulses with an Arduino. Most devices will provide 1000 oder 2000 count pulses per kWh.
So if you know the wattage of your pump and count the pulses from the wattmeter S0 interface, you can easily detect on-time from off-time and count together the total power consumption (which is also shown on the device).
im not sure I understand the problem.
the pump shold only run when there is water to pump . Irrespective of if you need water in your reservoir ?
sounds like you need a sensor that detects when water is available.
Hi, the op wants a watchdog timer, to monitor if the pump has been on for a longer than a normal period.
Duty cycle is probably a poor explanation around forum members who instantly think PWM control.
Tom.... 
it is typical to have a foot valve on the well. that means the pipe between the well and the pump should always have water.
if air enters from any location. then the pump could run dry.
you could put in a float switch to detect loss of water.
if the pump is running,, no matter how many valves are open, the pressure at the pump will be higher than further down the pipe. measuring pressure drop can show that there is flow. this can be as simple as a tee fitting that is one pipe size smaller and open up again.
Using the high pressure, and the the pressure drop, you can calculate flow volume. look at orifice flow meters.
motor temperature. no explanation needed.
if there is air in the line from the well or a leak, the pump will make noise. this is from the cavitation. cavitation can destroy the impeller. therfore knowing if air is in intake is important.
each type of reading is well withing the range of a novice.
motors run with electricity. the voltage and amps can be plotted as a set of curves.
when you add a load, the curves shift. it is possible to measure the motor and determine a quite significant amount of information about the operation of the motor.
this motor monitoring takes a lot more processing power, but an extreme amount of information can be gathered.
if you look at the information you can get from a variable speed drive, you can see what is available form these calculations.
thanks for all the replies ;D an example toilet didn,t shut off one night and continously ran and well pump cycled on and off all night
I would simply fix the toilet, because it will happen again. It is very simple, because toilet parts are all standardized (at least in North America).
it would be a simple matter to install a relay in the power line of the motor.
I would suggest you data log use.
time the use from a shower, a bath, a toilet, washing dishes. washing clothes....
not a good idea to shut the water off in the middle of a shower.
a party could have guests flushing the toilet repetitively, mimicking a leak.
If you monitor the pump current with a CT you can write a routine that runs a countdown timer that shuts off the pump and turns on a light and audible tone (piezo) if the pump is on too long. This could be done
with 555 timers but it would make more sense to use an ATtiny85 , Pro-Mini, or UNO.
What methods do you have for monitoring whether the pump is ON or OFF ? (Is there any ON light that is illuminated only when the pump is ON ? (That could be used as a sensor input to the arduino )
through pump switch can pull a 125 volt leg to power a relay to arduino uno or maybe a whole house monitor would jump by a few amps when pump is running, then ethernet to text on house conditions and send text meassages then a burgler alarm too, but baby steps first water
200 amp 220volt relays would be costly but could be integrated with backup power supply to run heat in the winter
through pump switch can pull a 125 volt leg to power a relay to arduino uno
or
maybe a whole house monitor would jump by a few amps when pump is running,
then ethernet to text on house conditions
and send text meassages
then a burgler alarm too,
but baby steps first water
Can we just deal with one issue at a time ?
trying to design a duty cycle monitor to shut off power if well pump is running to much
This is not a "duty cycle " monitor . This is a pump "STATUS" monitor (ON or OFF ?)
(as already mentioned , "duty cycle" is a term reserved for PWM signal discussions)
through pump switch can pull a 125 volt leg to power a relay to arduino uno
A relay is overkill. There is absolutely no need for a relay. STATUS indication can be obtained several different ways but I think the preferred method is opto -isolator.
This potential project is in line with one I am currently working on. My concern is water damage in our house. This is not a concern when someone is home, but of course it is when no one is home. The project consists of PIRs attached to transmitters. A receiver gets data sent by the transmitters. If no data is received within a window of time, a relay energizes, removing power to the pump circuit. - Scotty
Not sure if Midmofarmer (MIDdle MissOuri Farmer ?) has the same setup and same intention. If the pump
is wired to the N.C contacts of the relay, energizing the relay will break those contacts and turn on the pump.
trying to design a duty cycle monitor to shut off power if well pump is running to much
The above general description is still too vague to act on. More detail is required, particularly what
"too much" means.
If the pump
is wired to the N.C contacts of the relay, energizing the relay will break those contacts and turn on the pump.
If the relay is providing power to the pump through N.C. contacts and the contacts open there will be no power to the pump.
A receiver gets data sent by the transmitters. If no data is received within a window of time, a relay energizes, removing power to the pump circuit. - Scotty
These are your words. It clearly says "energizes" , meaning the pump wiring is rerouted through N.C. contacts on the added relay so when it energizes, it removes power from the pump. If you want to reword yours, I'll reword mine.