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Alexa turn on the air compressor

CarterKraft said:
Because there is no way the breaker is actually sized to the running current of the motor. That's not the purpose of a breaker.
The breaker is to protect the wire not the motor.

The "heater" in the starter can be tuned to within the 1 amp tolerance of the motors running current.
Click to expand...
Exactly, the ones that work we adjust the overloads to match the individual motors (480V 3 phase fan motors), even between different brands of the same frame size, rpm, and horsepower there will be .3 to .5 amp difference in how much power the motor pulls and we try to adjust to match what the motor is actually pulling when working that so that if the motor goes bad we only have to replace the motor, not the motor and 50-200 feet of wiring.
We usually have a breaker for the panel, a set of fuses for each group of 2-5 motors, then come out of that to a overload, then a contactor (like a relay, but bigger).
The power to engage the contactor runs through the auxillary contact on the overload so if the overload trips it drops out the contactor.
Then we use the auxiliary contact on the contactor to provide feedback to the PLC that everything is working as expected and there is power going to that particular fan motor.

Aaron Z
 
So if one were running a 3p motor off a VFD, is it necessary or even possible to use a heater? Or is the VFD's overload protection enough to handle it?
 
bgaidan said:
So if one were running a 3p motor off a VFD, is it necessary or even possible to use a heater? Or is the VFD's overload protection enough to handle it?
Click to expand...
As far as I know, the VFD should provide overload protection.
Not over familar with them as we have less than a dozen VFDs out of the hundreds of motors we use, we use soft starts on some of the bigger ones and but the small ones cycle on and off.

Aaron Z
 
aczlan said:
As far as I know, the VFD should provide overload protection.
Not over familar with them as we have less than a dozen VFDs out of the hundreds of motors we use, we use soft starts on some of the bigger ones and but the small ones cycle on and off.

Aaron Z
Click to expand...

That was kind of my feeling. I'm more concerned with the one on the compressor as I won't be right there with it when it's running. I was playing with my almost restored lathe last night - 3hp with a 3hp rated vfd and I found that the overload is sensitive enough that if I jam the clutch in to gear a the highest spindle speed, it'll trip the VFD. If I float it just a tiny bit it's fine. Every other speed I can slap it right in without a problem. There's probably a parameter that I can adjust to tweak that a bit.
 
bgaidan said:
That was kind of my feeling. I'm more concerned with the one on the compressor as I won't be right there with it when it's running. I was playing with my almost restored lathe last night - 3hp with a 3hp rated vfd and I found that the overload is sensitive enough that if I jam the clutch in to gear a the highest spindle speed, it'll trip the VFD. If I float it just a tiny bit it's fine. Every other speed I can slap it right in without a problem. There's probably a parameter that I can adjust to tweak that a bit.
Click to expand...
There is probably a setting to increase the time delay before it trips, I might start with that.

Aaron Z
 
For my ghetto 60yo IR compressor with a 3hp 240v motor that turns 3450rpm (it was put together out of stuff laying around):
120v well pressure switch set at 125psi (think it maxes out at 130:laughing:)
240v relay intended for a central air unit (control side is 120v/240). This one does interrupt both legs, some don’t. Can’t remember the model but it’s hardware-store stuff.
Household outlet wired into light switch that controls shop lights, supplies power to the pressure switch.

This way, anytime the lights are on the compressor CAN run. Lights off? Can’t turn on.
The compressor with 60 gal. tank and bad motor was $30 at auction. Heavy AF by the way. At the time the well pressure switch was $20 or so and the relay was $30-40? Also $10 for an under drive pulley to slow down the compressor with that high rpm motor on it.
Painted vehicles with it, ported heads, lots of high volume/high on/off cycle stuff for the compressor over the years and none of it has failed. Never have to worry about it running when I’m not there.
 
CarterKraft said:
Because there is no way the breaker is actually sized to the running current of the motor. That's not the purpose of a breaker.
The breaker is to protect the wire not the motor.

The "heater" in the starter can be tuned to within the 1 amp tolerance of the motors running current.
Click to expand...

Right. My point is, on a dedicated circuit, and the breaker is sized for the max amp rating of the motor (not higher), there is no benefit other control overload protection. Wire is sized larger than the amp rating of the breaker in all cases (including mine).

Otherwise, I see your point. Fwiw, the Bridgeport I bought from a machine shop, where it served for many decades, had no heaters wired up between the feed and the spindle motor drum switch. No mag starter.

Not ideal I understand though. Maybe I'll pick one up for the air compressor, would make it easier to remote control anyway.
 
aczlan said:
Exactly, the ones that work we adjust the overloads to match the individual motors (480V 3 phase fan motors), even between different brands of the same frame size, rpm, and horsepower there will be .3 to .5 amp difference in how much power the motor pulls and we try to adjust to match what the motor is actually pulling when working that so that if the motor goes bad we only have to replace the motor, not the motor and 50-200 feet of wiring.
We usually have a breaker for the panel, a set of fuses for each group of 2-5 motors, then come out of that to a overload, then a contactor (like a relay, but bigger).
The power to engage the contactor runs through the auxillary contact on the overload so if the overload trips it drops out the contactor.
Then we use the auxiliary contact on the contactor to provide feedback to the PLC that everything is working as expected and there is power going to that particular fan motor.

Aaron Z
Click to expand...

If a motor can burn out 50-200' of wiring, it sounds like you need to downrate your breakers. The breaker is supposed to protect the wiring from burning up under any circumstance. That's kind of my point.
 
I still love this fucking thing.
Walk in the shop go about my business and need air, yell out "alexa turn on the air compressor" valve opens and the compressor turns on, line fills and if needed the motor runs to refill the tank.
Don't have to worry about leaving it on I have a schedule set to turn it off at 1 AM every night weather its on or not.
I am going to add a solenoid to the drain line and put it on a IFTTT routine to auto drain.
 
I have been wood butchering lately, I used another smart plug to run my ghetto dust collector.
I made a routine for it too, I say "dust collector" and it pauses the firestick on my shop tv, runs the dust collector for 3 minutes then turns it off waits 5 seconds and un pauses the fire stick. Fucking awesome.
I know ya'll are gonna call me a fag, I don't care I pay for this shit so ya'll can kiss my ass. :rainbow:
 
My shop has smart switches and plugs, these things rock, literally. Outside lights and one row of inside lights have smart switches. Stereo, dust collection and window fan have smart plugs. Plus I have a nest thermostat in the shop. I can preheat, light and tunes before heading out. In the summer I turn on the window fan when the outside temperature drops and turns off at 7am, almost as good as AC for MI. My compressor has a timer that I pass walking into the shop, turns on/off power and an air solenoid
 
_ogre said:
My shop has smart switches and plugs, these things rock, literally. Outside lights and one row of inside lights have smart switches. Stereo, dust collection and window fan have smart plugs. Plus I have a nest thermostat in the shop. I can preheat, light and tunes before heading out. In the summer I turn on the window fan when the outside temperature drops and turns off at 7am, almost as good as AC for MI. My compressor has a timer that I pass walking into the shop, turns on/off power and an air solenoid
Click to expand...
The ability to schedule stuff is a game changer, and much cheaper/easier than individual timers.
 
Nothing screams dollar signs like walking into a warm shop after a subzero night to find you left the heat turned up. Had the smart plugs been around A couple years ago I'd have one for the compressor, instead of the timer. Heat turns down every 4 hours. All switches and get off at midnight command.
 
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