Long-time reader, first time posting.
I wish I was asking this question under less pressured circumstances, but I’ve encountered a problem at work today that I’m hoping we might be able to build me out of.
I won’t bore you with the details, but I have a site I have to inspect once a week that is about 2.5hrs drive away from my office. We have a 3-phase compressor on site that operates all the pumps, without it nothing works. This compressor is new and has been installed and checked by multiple electricians. Despite this, it trips out once every so often (2-twice a month-ish).
This week it was particularly bad as the compressor tripped after approx. one running hour after my previous inspection. As you can imagine this has provided me with no end of headaches and lost productivity.
What I would like to do is wire up a CT clamp to one of the 3-phase lines and an ESP32 GSM module to make create an SMS alarm if the power supply is lost to the compressor. It doesn’t have to read or display the voltage, only report via SMS if it is lost. I have access to constant 240v in the unit so I can run the board no problem but no WIFI. The reason for the CT clamp is I’m no electrician and they are non-intrusive.
Now, in the same vein that I am not an electrician, I’m not really an experienced electronics guy, yet. My experiences end at node-red really but had been planning a remote water tank level build in the near future (Hence why I have an ESP32 to hand).
So, could anyone provide any opinion on how difficult this project will be, or if it's even feasible in the form that I have described, or if there are better options that I’ve just not seen? Also, if there is any project you could think of that I could modify (Code ect) to help.
The completion of this project will potentially save me wasting 5hrs a day driving at increased intervals over the week so any help/insights would be greatly accepted.
It's plausible. You should be able to find plenty of projects that send SMS from an ESP32. Also, plenty that use a CT to detect power - home energy monitors for example.
I don't know what you mean by "tripped out". But if you machine is switched on-off by a magnetic contactor. The contactor likely has replaceable thermal sensors that should be replaced.
Paul
Your project seems straight forward. As this is work related are you interested in paying someone? If you are in the UK I know someone who might be interested in the commission. If that's the case send me a PM an I'll ask him if he wants the job.
wildbill:
It's plausible. You should be able to find plenty of projects that send SMS from an ESP32. Also, plenty that use a CT to detect power - home energy monitors for example.
Then it's "just" a matter of combining them.
That's good to hear, I just need to work out how to change the code to meet my needs.
Paul_KD7HB:
I don't know what you mean by "tripped out". But if you machine is switched on-off by a magnetic contactor. The contactor likely has replaceable thermal sensors that should be replaced.
Paul
Yes, sorry. Tripped out is English for the fuse has switched off. Had someone look at it (massive call out charge) and found nothing wrong. I think it might have something to do with the surge of power on startup. It can go weeks without happening and then do it twice in a week.
SteveMann:
Get one of these. Detecting if a motor is no longer working should be easy.
Easy enough to get a 3.5 jack on the board I have or would I be better off buying another one?
PerryBebbington:
Your project seems straight forward. As this is work related are you interested in paying someone? If you are in the UK I know someone who might be interested in the commission. If that's the case send me a PM an I'll ask him if he wants the job.
Yes, this is something i would be interested in, but only if i can manage it myself (Highly likely by this point)
jremington:
Sounds like the system design is at fault.
I suggest to hire a mechanical engineer to check whether the compressor meets the requirements of the task.
The same system is used all over the country, this one just has a bug. It's temporary also so will only be running for another 18 weeks.
jremington:
Sounds like the system design is at fault.
I suggest to hire a mechanical engineer to check whether the compressor meets the requirements of the task.
My idea too. I understand that Ypu need to make that 5 hour travel to restart the compressor. Making a restart, travelling home and SMSs start coming again....
Investigate what reason for the stopping. Eliminate that reason.
A second thought is if the restart can be done remotely as well.
Your commercial electric power utility has monitoring devices they can place on the line going to the compressor motor and will record every possible power problem you might be having. In the US, they install it and let it set for weeks at no charge. Don't know about your supplier.
Could be anything, even one phase not supplying the correct power/voltage/phase. Is you supply from 3 transformers on poles or underground?
Paul
Watching reports from US I'm amazed by all power lines "up in the air", on poles.
Here, in Europe, Sweden, the grid is all under ground except for the long distance high voltage power lines and country side lines.
The most common failures are caused by trees falling into the country side pole lines.
Your problem is that when the compressor reaches its set pressure it will switch off , so measuring current tells you nothing unless it can be combined with something else .
( eg the pressure switch ?)
Finding out why it trips might be a better way forward ... what trips it out and why ?
Sweden has ~10.6M people, compared to ~335M in the USA spread over so much more land and with power developed mostly independently state by state, and which controls how power is installed.
I live in MA, we have a mix of underground wiring in new locations (houses on my street went up in the 1989-1990 time frame and wiring is underground) while older locations have above ground (like the street which my street connects to). So it seems to be a local zoning thing also that the individual towns within the states had a say in. I'm sure the older wiring was installed the lowest cost method possible.
I've also read that it costs a million dollars a mile to bury the wiring, so I don't see much modernization happening any time soon.
Underground wiring can also fail - they've had to dig up the wiring under the street twice since we lived here, once where a junction failed across the street from me, under the sidewalk, and a 2nd time under the street in front of my house when a wire failed open (probably got nicked when a fire hydrant was moved years prior to the failure). And occasionally something happens in the big distribution box farther down the street. Usually we lose power when something has happened out on the larger street tho, like a tree on the wires, or someone hitting a utility pole.
Yes, under ground usually costs a lot more to install. The maintenance costs are considered to be lower. The greatest danger is other various under ground work like when the waist water guys and their excavators cut the electrical line. Repair is fairly easy because the hole is all ready there....
Other reasons for under ground is safety. No dangerous lines falling down on the public.
In my near town, Gothenburg, trams are used intensively. Various trucks equipped with cranes or other high reaching stuff tears down that power line.....
We only have one "state", the nation...
All planing for dense populated areas is done "under ground" as water, waist water and electricity is done at the same time.
Every "country village" use under ground. "Out in the country" poles are common but in the case of renewing an old road under ground electricity is usually done.
jegz:
What I would like to do is wire up a CT clamp to one of the 3-phase lines and an ESP32 GSM module to make create an SMS alarm if the power supply is lost to the compressor.
A few things here......
First, if the compressor has fuse protection and you want to add a ct to one line only, it is possible you would pick the wrong fuse, a 1 in 3 chance, that is even if it is the fuse that blows, or in your words, trips.
Second, when a unit "trips" it is usually referenced to the overload device in the control circuit which can be set to auto-reset when cool.
Compressors can trip due to unbalanced supply which would need a site inspection to ascertain, or pressures set too high or simply the duty cycle has been exceeded.
There will be a maximum number of starts per hour allowed in the compressor design.
If it were circuit breaker protected on a single 3 pole breaker, then "trip" could refer to this device and a single ct would be ok but would tell you nothing more than you already know, it stopped.
Circuit breakers have many types of curves for different applications and it may be that the wrong type has been fitted.
It wouldn't be the first time a spec called for a 3 phase outlet to be installed (for which a standard curve breaker would suffice) and along comes Bob the Builder and plugs in a 3 phase compressor.
After all, it just 3 wires , right, how hard can it be? ...mmmm...not so.
As earlier suggested, get either a lecky with some knowledge in the subject or engage an engineer.
A phone call to the suppliers of the compressor may also be beneficial.
Railroader:
Watching reports from US I'm amazed by all power lines "up in the air", on poles.
I am, too. And I live here.
Our town experiences power outages almost every time it rains and every time we have a wet, heavy snowfall. My neighborhood has buried utilities and we have only had a power outage two or three times in the past ten years.
I asked a city engineer why underground utilities aren't mandated for all new construction. His reply (typically American) was that utility poles are cheaper.
I wonder if the compressor is a piston type, or a worm type device and if it is variable frequency driven or not?
Does it have an air tank? Or is it really a big device.
Whatever device you have, the best way to see if you have a problem or not is to look at the air pressure, because that is the target of the exercise. So you could decide to hook op a simple pressure switch and let it close a contact to your Arduino device. From there on you can use all the advice mentioned above?
Now, related to the modi of failure of the compressor, there are possible causes of failure not mentioned above: Standard compressors have a non return valve that blocks the air coming out of the air tank and going back to the piston. The tube between the valve and the piston is emptied by a mechanical valve in the pressure switch. If this mechanism fails, the motor is unable to start because of the back pressure on its piston. So the release circuit needs to be tip-top in order to work properly. The compressor fails to start the moment it needs to and then the circuit bleeds empty.
Therefore determining the air tank pressure at which your compressor fails could say a lot about the possible causes of the problem. Additionally, knowing that the compressor was running or knowing that it did not restart can also be very valuable.
You no not have to modify the compressor to hook something up to your air grid.
I have addressed this problem multiple times with a product I developed a couple of years ago.
Monitoring the generator run state (e.g loss of fuel, stall...) , generator output present, pump output pressure (broken pipes) etc, as well as enabling / starting and stopping the individual elements of the system.
There quite a few cheap ‘SMS Notifier’ devices out there (eBay etc). Watch out for 2G/3G/4G compatibility as the cell networks evolve.
ADVERT:www.SL4P.net - with 4 inputs and 4 controlled outputs. Always in stock.
JOHI:
Standard compressors have a non return valve that blocks the air coming out of the air tank and going back to the piston. The tube between the valve and the piston is emptied by a mechanical valve in the pressure switch. If this mechanism fails, the motor is unable to start because of the back pressure on its piston.
You will find most larger piston compressors have a lock out installed if the motor tries to start without this head pressure released.
Reason being, there is a possibility of the motor actually snapping the crankshaft.
I've seen it happen in a dodgy installation.
These days it is more common to have screw compressors, quieter and lower starting loads.
(Highly likely by this point)