creating a run time alarm for an electric motor

A few years ago I started to explore whether I could make a run time alarm .. Now I see there are current sensor modules.
What I want to do is monitor a remote motor via a CT or current sensor. when the remote motor runs a delay clock starts.. and if it does not reach a set time by the time the motor shuts off, the clock resets... but if it does reach an allotted time then a relay contact is closed to another circuit.
I do not care to measure the current.. just that when it starts the time starts and when it stops the timer resets waiting for the next run. the time does not have to be exact.. it can vary by a few minutes.

Is what I want to do feasible? and could I fix up more than one sensor per micro controller?

the voltage of the motor is 240v ac. but would only need to monitor 1 'leg' or 120v AC
the motor is less than 1/2 hp or less so current would be under 10A

That sounds feasible...

Rather than sensing current it would might be be "easier" to sense if voltage is applied to the motor. And the easiest way to do that is with a relay that has a 240V (or 120V) coil.

And if you wanted to, you could add another relay to kill the motor of someone ignores the alarm for x-minutes.

the time does not have to be exact.. it can vary by a few minutes.

The Arduino clock doesn't make a great clock, but it's not that bad and you shouldn't be off by minutes unless you're timing for days. I've forgotten the specs, but the resonator's accuracy is measured in parts-per-million (maybe 100-200ppm?).

How "remote" is remote? And how would the data get to where the Arduino is located?

Paul

ok . to answer a couple questions and more clarification....

How remote? the motor I want to monitor can be up to 400+ feet away... but I have access to the individual power wires to each one in one location..
adding relays to the motor is somewhat feasible... but impractical and can create alot of extra wiring long cables.

the motors I want to monitor are feed line motors in a poultry house setting. The end pan by the motor has a switch in it that starts and stops the motor. I figured current sensing would be better since I have access to the individual circuits in one location right where I would have the arduino units.

what I am trying to do is to have a run time alarm that would alert me by opening a NC alarm circuit that is already existing. like I said before time is not critical down to the second... 5 or 10 minutes range would not be an issue.
also illuminating a LED to indicate a fault.
In my application I want to monitor at least 6 motors at one time, each with its own current sensor and runtime alarm.

Ok, got it.

Does your alarm system run to each motor? Does it alarm with a power failure? If your monitor opens the alarm wire, does it remain open until manually reset or does a momentary open, then back closed trigger the alarm properly?

Paul

a CT or cutternt transformer is easy to use so that is an option.
any sensor that on the voltate to the fan would also be able to send a signal
connecting a 100k resistor {proper selection based on existing voltage ] and an LED is simple, so you can see when the motor is running.
using that same signal to your micro is not hard.

if you have WiFi available, your ESP8266 can connect to your WiFi.
an ESP8266 can detect the on/off of voltage or the LED, but I think you would need to do a lot more to use a CT into the ESP8266 as the 8266 has a much smaller Aanalog to Digital converter.

if you do not have WiFi available, then you need to use one of the RF modules.
if your fans are in separate buildings, then you would need one Arudino at each building/fan, connected to the transmitter.

I would offer that one ESP8266 located near your WiFi would make life easier.
have your one ESP8266 at the WiFi, and have it poll each of the sensors every minute.
if sensor #3 is HIGH, showing the fan is on you would be able to log it as on and running and also start a timer for fan #3
once it goes off, you can log it as off and note the duration of the run time.

if your run time exceeds the time alloted, you can send an alarm to your phone that #3 is running for more than X minutes.

I am making up this as I go along as I do not know your specific needs.

a single EXP8266 with an RTC and a data logger, that is near yoru WIFI,
and infividual RF nodes, one at each fan, or one in each building, could relay the status of each device.

communication can be as simple as the ESP sending a signal, once every 30 seconds
and poll the status of the nodes at the fans.
ESP - attention node1, what is your status = node1 to ESP OFF
ESP - attention node2, what is your status = node2 to ESP OFF
ESP - attention node3, what is your status = node3 to ESP OFF
ESP - attention node4, what is your status = node4 to ESP OFF
ESP - attention node5, what is your status = node5 to ESP OFF
ESP - attention node6, what is your status = node6 to ESP OFF

in 3 minutes, you know the conditions.
repeat every 5 minutes.

the ESP could data log any RUN times.

ESP - attention node3, what is your status = node3 to ESP ON

ESP = datalog that at 6:27 node 3 went HIGH
start noide3 timer

at 6:30 ( the next loop to poll all the units)

ESP - attention node1, what is your status = node1 to ESP OFF
ESP - attention node2, what is your status = node2 to ESP OFF
ESP - attention node3, what is your status = node3 to ESP ON
ESP - attention node4, what is your status = node4 to ESP OFF
ESP - attention node5, what is your status = node5 to ESP OFF
ESP - attention node6, what is your status = node6 to ESP OFF

ESP = node 3 is till HIGH, keep count time
check noide3 timer, if it exceeded the run time, send alarm

at 6:35 ( the next loop to poll all the units)

ESP - attention node1, what is your status = node1 to ESP OFF
ESP - attention node2, what is your status = node2 to ESP OFF
ESP - attention node3, what is your status = node3 to ESP OFF
ESP - attention node4, what is your status = node4 to ESP OFF
ESP - attention node5, what is your status = node5 to ESP OFF
ESP - attention node6, what is your status = node6 to ESP OFF

ESP = node 3 has changed status and is not OFF
check noide3 timer, datalog the fan is now OFF

then the ESP could note the time ON and OFF and list minutes of run time.
this would be accurate to 10 (19?) minutes as the fan could start one second AFTER you did a poll and end one second BEFORE you did your next poll.

as an alternate polling, you could ask how long have you been running ?

ESP - attention node1, how long have you been running ? = node1 to ESP 0 seconds
ESP - attention node2, how long have you been running ? = node1 to ESP 0 seconds
ESP - attention node3, how long have you been running ? = node1 to ESP 372 seconds
ESP - attention node4, how long have you been running ? = node1 to ESP 0 seconds
ESP - attention node5, how long have you been running ? = node1 to ESP 0 seconds
ESP - attention node6, how long have you been running ? = node1 to ESP 0 seconds

the ESP would do the math on timing.

let us know what your needs really are.