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A 'would this work' thread for small machineshop

Ok, have a small 'haunted' machineshop where we have had some weird failures which could have been prevented if the power was just off.

begin tldr, ignore this paragraph if you want.
The bizarre one was an air compressor with the pressure switch IN THE OFF POSITION broke and contacts fused closed, and since no airline was connected the PSI was probably in excess of 350psi (conservative estimate) on a 200psi rated tank. The copper from the pump was blued, lime green ceramic paint turned to hunter green, and one heck of a grease mark on the wall when the diaphragm let loose as the weakest link. Discovered it and immediately pulled the main, opened a valve, and got the heck away from it because the 250psi gauge was super extended. it took 1 minute or so before the gauge started moving on an 80gallon tank and froze the pipe open until thawed. Camera footage confirmed the pressure switch was off, and it was off when I found it.
/tldr

So we have a policy where everything except the bathroom, lights, em lights, and vending machine get turned off at the breaker panel before leaving, but that can be quite challenging. to enforce. Lets assume when I say breaker I mean the one at the disconnect for each device, not at the main service panel.

The current proposed solution was installing a panel near the door with a lot of red/green lights. Green = circuit live, red or off = circuit open. This would be very simple for me to do with relay logic but would require some wire to run.

Adding to the current proposed solution would be retrofitting to shunt trip breakers which are really pricey to add the capability to trip all of the breakers needed right from the door before heading out. Or I could use contactors/relays instead of shunt trip breakers. (would prefer the latter so resetting would be easier)

Now since discovering mFi, would I be able to automate this? My goal would be to from 1 screen see what circuits are live, and be able to turn them off (via contactor/relay instead of breaker)

Another big goal for this is for when crap hits the fan, somebody can just go run over to the front door panel OR main service panel to shut everything down because theres been times where we have had to do that. Id love to run to the front and frantically mash a bunch of trip circuits buttons. which this failsafe i wouldnt want tied into mFi at all. for this we are talking safety which there would be no way where it should go through something complicated.

All that being said, I have my flamesuit handy, but around these parts this kind of stuff is the norm. Ive seen systems like this, but my small machineshop isnt a tens of millions of dollars for a manufacturing facility. I just want the toys they have.
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Re: A 'would this work' thread for small machineshop

Time for an all day safety "what if" walk through.
WHT = Short Form Acronym for "You couldn't handle me even if I came with instructions!"
Well engineered projects are indistinguishable from crazy ideas.

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Re: A 'would this work' thread for small machineshop

Google click plc


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Re: A 'would this work' thread for small machineshop

Use nice direct switching systems; you have
no need for computer-controlled logic systems.
Control wire is dirt-cheap; you can even use
CAT5 cable if you chose a 24V control relay
to energize contactors. Dave

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Re: A 'would this work' thread for small machineshop

Use nice direct switching systems; you have
no need for computer-controlled logic systems.
Control wire is dirt-cheap; you can even use
CAT5 cable if you chose a 24V control relay
to energize contactors. Dave

I normally wouldn't suggest it, but it's dirt cheap and incredibly easy to use, especially for something like this.


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Re: A 'would this work' thread for small machineshop

Maybe, but it's an added cost; he will stilll
need relays and contactors and wire.

What's the advantage--pizzaz? Dave

> HQ in Seacoast region New Hampshire U.S.A.
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Re: A 'would this work' thread for small machineshop

Maybe, but it's an added cost; he will stilll
need relays and contactors and wire.

What's the advantage--pizzaz? Dave

Easy future expansion, automation, logic action. Ie: flow valve closed but pressure switch triggered shut down the compressor, turn on red strobe.


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Re: A 'would this work' thread for small machineshop

Those actions and 'logic' are so basic
and simple, relays and contacts can
easily handle them.

I love gadgets, I love programmable
equipment, I don't like relays much.
But I don't see any traction here. Dave

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Re: A 'would this work' thread for small machineshop

First thing I would do is get an emergency pressure relief valve on that compressor!
I have a 120 gallon tank in the barn with a relief valve. And another on the tank in the shop.
It's a must have in the barn. Mine both have a key ring on them so a gentle tug will open them for testing that they are not stuck.
http://www.amazon.com/Thread-Safety-Pressure-Relief-Compressor/dp/B005CS4MVS
Walks in, tells it like it is, walks out , milks a cow
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Re: A 'would this work' thread for small machineshop

I had always thought an over-pressure valve
was standard--even required--for any air
compressor with a storage tank.

Add to that a pair of pressure-control switches
in series. The chance of two switches failing at
the same time is incredibly low. Dave

> HQ in Seacoast region New Hampshire U.S.A.
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Re: A 'would this work' thread for small machineshop

Pressure relief valves are cheap and easy to add, that really shouldn't be an issue.
www.mcmaster.com/#standard-relief-valves/=j9ohya
edit: Hrm, that doesn't exactly link to the one I wanted to show you... their web page is weird. Ohwell.


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Re: A 'would this work' thread for small machineshop

I had always thought an over-pressure valve
was standard--even required--for any air
compressor with a storage tank.

Add to that a pair of pressure-control switches
in series. The chance of two switches failing at
the same time is incredibly low. Dave



Yea, about that. The pressure release valve wasnt working properly so we removed it and was waiting on a replacement... Murphy doesnt like me when it comes to air compressors. Fortunately my shop's only mishaps are air compressor related; no exploded forklift batteries yet.

Im really good at relay logic and thats the method I was leaning towards, was just curious on mFi since discovering it to see if it would/could work for this application. unrelated: Im the guy in our company they call on when they needed a logic circuit built for a mantrap for a high end jewelry store. That was fun to work on and works great. I did with half a dozen relays what the manufacturers own board in their own mantrap couldnt achieve reliably. Kept frying boards, randomly turning the locks off, going into alarm, etc..

From a safety standpoint, KISS and there is nothing simpler than 'mash button A which opens circuit to contactor control coil which opens contactor which shuts machine down' The green/red light would be achieved by a relay which is also on that same control circuit assuming I had 120v at my panel, but even without 120v the whole interrupting the contactor coil circuit would still work, just the lights wouldnt.

As for using a PLC for 'value adding' I think sure that would be great in the future, but not for the whole emergency shutdown part of this.

Now, my idea is wondering towards this: if mFi motion sensor doesnt detect movement, both doors are closed (doors to shop are open when occupied), main lights are off, wait 30 minutes then trigger shutdown of all machinery. basically from an interface standpoint I would just be adding relays inline with the 'button As' I listed above for mFi to control. Im thinking this is a little better as the hardware would be a motion sensor on an mPort, and one of the mPower strips or single.
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Re: A 'would this work' thread for small machineshop

A time-delay relay is cheap; you can easily
find a motion detector with a relay contact. Dave

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Re: A 'would this work' thread for small machineshop

The mfi motion sensors are pretty damn touchy, I'll give them that


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Re: A 'would this work' thread for small machineshop

The mfi motion sensors are pretty damn touchy, I'll give them that

I use mine to know when to set the mouse traps in the garage.
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Re: A 'would this work' thread for small machineshop

I live on a farm. If they detect mice I bet I could short a few out!!
Can they be set lower so a cat could walk past and not set it off?
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Re: A 'would this work' thread for small machineshop

Yes. There is an adjustment.
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Re: A 'would this work' thread for small machineshop

Ok, have a small 'haunted' machineshop where we have had some weird failures which could have been prevented if the power was just off.

begin tldr, ignore this paragraph if you want.
The bizarre one was an air compressor with the pressure switch IN THE OFF POSITION broke and contacts fused closed, and since no airline was connected the PSI was probably in excess of 350psi (conservative estimate) on a 200psi rated tank. The copper from the pump was blued, lime green ceramic paint turned to hunter green, and one heck of a grease mark on the wall when the diaphragm let loose as the weakest link. Discovered it and immediately pulled the main, opened a valve, and got the heck away from it because the 250psi gauge was super extended. it took 1 minute or so before the gauge started moving on an 80gallon tank and froze the pipe open until thawed. Camera footage confirmed the pressure switch was off, and it was off when I found it.
/tldr

So we have a policy where everything except the bathroom, lights, em lights, and vending machine get turned off at the breaker panel before leaving, but that can be quite challenging. to enforce. Lets assume when I say breaker I mean the one at the disconnect for each device, not at the main service panel.

The current proposed solution was installing a panel near the door with a lot of red/green lights. Green = circuit live, red or off = circuit open. This would be very simple for me to do with relay logic but would require some wire to run.

Adding to the current proposed solution would be retrofitting to shunt trip breakers which are really pricey to add the capability to trip all of the breakers needed right from the door before heading out. Or I could use contactors/relays instead of shunt trip breakers. (would prefer the latter so resetting would be easier)

Now since discovering mFi, would I be able to automate this? My goal would be to from 1 screen see what circuits are live, and be able to turn them off (via contactor/relay instead of breaker)

Another big goal for this is for when crap hits the fan, somebody can just go run over to the front door panel OR main service panel to shut everything down because theres been times where we have had to do that. Id love to run to the front and frantically mash a bunch of trip circuits buttons. which this failsafe i wouldnt want tied into mFi at all. for this we are talking safety which there would be no way where it should go through something complicated.

All that being said, I have my flamesuit handy, but around these parts this kind of stuff is the norm. Ive seen systems like this, but my small machineshop isnt a tens of millions of dollars for a manufacturing facility. I just want the toys they have.


Like I have been told many times here "Call a professional" If I walked away from a job and claimed it was haunted I would be shot. Call a qualified electrician to check your installation or if you have an onsite electrician get a new one. I would recommend checking all the overloads and insure they are correctly set.

Overloads are the oldest and most reliable way to ensure electric motors never work beyond their limits. If the overload is correct then the motor must be oversized.
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Re: A 'would this work' thread for small machineshop

I'd probably just do it with relays too. You could have mfi control the relays at a later date. MFI probably doesn't have the current rating to handle your compressor's power input anyhow.
At home, I have a big relay box next to my breaker panel. Inside, every light in the house is homerun to the relays (all lined up on din rails). Light switches are all cat-5e and operate the relays. Eventually, I'd like something like mfi or otherwise computerized control the relays based on light switch inputs, computer scripts, web, and a big energy saving shutdown button by the door.
As it is now without computer, I can rewire light switches to do different/more lights from a big row of 110 punchdown blocks in the basement.
I've also used dpdt relays to "lock each other out"; in my darkroom, if the safelight is on, I can not accidentally turn the normal light on, as the safelight relay opens the normal light relay when the safelight circuit is closed.
Whatever you do, document it well. Marker fades and wipes off. People forget and get confused.
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Re: A 'would this work' thread for small machineshop

Like I have been told many times here "Call a professional" If I walked away from a job and claimed it was haunted I would be shot. Call a qualified electrician to check your installation or if you have an onsite electrician get a new one. I would recommend checking all the overloads and insure they are correctly set.

Overloads are the oldest and most reliable way to ensure electric motors never work beyond their limits. If the overload is correct then the motor must be oversized.


I knew this post was coming, it was inevitable. And yes, I have a qualified electrician doing all of my work, any work that requires a permit does infact get permitted, and when we do something, we do it right. Which is why I am here asking all of these questions.

As for the overloads, I guess it must have been in spec because nothing tripped. 5hp single phase motor (even though I have 3 phase, I changed the motor out when I had this compressor at my house) on a 2 stage head and 80gallon tank (1976 models) and the main disconnect has the correct sized breaker and at the panel is the correct sized breaker. So either A) the overload on the motor is bad or B) it never goes out of spec. It is one of the best continuous duty Baldors out there that are rated to run pretty dang hot.

And yes, I am a labeling fanatic. You should see my breaker panels and outlets.