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Forum topic by jiim posted 570 days ago 5063 views 2 times favorited 44 replies Add to Favorites Watch
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jiim

9 posts in 571 days


570 days ago

I want my dust collector to run when I start a wood working tool. I thought about using a current sensor as a trigger device and want to locate the current sensor in the circuit breaker panel. I have 9 woodworking tools that are on their own dedicated circuits. They are a mixture of 120v and 240v. Can more than one circuit pass through a current sensor? I want to mount 1 current sensor on each side of the 250a circuit breaker panel. Worst case is that I need 9 current sensors. The part I’m not sure about is what type of device can control the current sensors and then trigger a relay that starts the dust collector. I want the relay to have a built-in ‘delay off’ because my dust collector manufacturer does not recommend power cycling the collector more than 6 times an hour. The dust collector is 3hp @ 16a. Has anyone figured this out? BTW, my dust collector came with a wireless remote but I want a better solution.


44 replies so far

View DouginVa's profile

DouginVa

486 posts in 904 days


#1 posted 570 days ago

Have you looked in to these?

http://www.woodcraft.com/product/2080165/28298/ivac-automated-shop-vacuum-switch.aspx

I have a very small shop (12×18) and I use this switch for my table saw, jointer, and router table. It works great and does what it says it does.

-- Just a man with his chisel.........

View EEngineer's profile

EEngineer

887 posts in 2244 days


#2 posted 570 days ago

There was a Fine Woodworking article called “Dust Detector” that does most of what you need. Google it – I found the PDF out there somewhere. It answers most of your questions.

The part I’m not sure about is what type of device can control the current sensors… Commercial current sensors are available that will drive a power relay directly. They are available from Grainger.

Can more than one circuit pass through a current sensor? Yes – the “hot” lead from each tool can be passed through the current sensor ring. The sensitivity on commercial current sensors will probably have to be set for the lowest current tool you have. The author of the article above says that he could get up to 6 leads through the current sensing ring.

I want the relay to have a built-in ‘delay off’… They make adjustable time delay relays that do this – also available from Grainger.

In short, everything you need to do this is available off-the-shelf from Grainger. If you can handle shop wiring, you can probably handle this. Reference the article above to get an idea of how the wiring is done.

I do electronics so I rolled my own using a simple current transformer, some electronics and a solid-state relay to do this for dust collection on my miter saw. Now, every time I fire up the miter saw it powers up a small shop vac for dust collection. Very slick.

-- "Find out what you cannot do and then go do it!"

View redryder's profile

redryder

2138 posts in 1732 days


#3 posted 570 days ago

I have a wireless remote with my dust collector. I don’t find pushing a button to be that much hassle. Now opening and closing every blast gate I do get tired of…....................

-- mike...............

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jiim

9 posts in 571 days


#4 posted 570 days ago

Thanks everyone for the replies.
DouginVa, the iVAC Automated Shop Vacuum Switch will only handle 1 woodworking tool per dust collector so it won’t work so well for me. I do have several of DCG’s i-Socket which I believe work on the same principal as the iVAC Automated Shop Vacuum Switch.

EEngineer, I have a hardcopy of Fine Woodworking article called “Dust Detector”. The article did an excellent job of outlining how to set this up. That’s where I got the idea to use a current sensor but the author only showed one tool outlet.
I just reread the article and my original take on the current sensor was that they were commenting on the size of the donut and not if you could pass multiple circuits through it.
I contacted a sales rep earlier this week for an ac current sensor I found online. He thought you could only pass 1 ‘hot’ circuit wire through the current sensor at a time because it would cause a false reading.
Since the current sensor is only detecting amperage, could both 120v and 240v ‘hot’ wires pass through the donut of the current sensor?
I want to mount 1 current sensor on each side of the circuit breaker panel. Would I need a 2PST relay for the current sensors? If both current sensors were to trigger the relay at the same time would the relay contacts bounce?
I been researching relays with built-in ‘delay off’ but most of them are rated for 15a or less. I will keep looking.

Redryder, I setup my blast gates to open when I turn on a tool and close when the tool is off. I use a pneumatic cylinder to open/close the blast gate and pneumatic solenoid wired between the on/off switch and the motor of my 240v tools. I use the i-Socket for the 120v tools. The blast gates are still a work in progress but I’m pretty close to completion.

View EEngineer's profile

EEngineer

887 posts in 2244 days


#5 posted 570 days ago

I just reread the article and my original take on the current sensor was that they were commenting on the size of the donut and not if you could pass multiple circuits through it.

Well, he was. The limitation is physical: you can’t get more than 6 wires through the little hole. But, and I quote from the article: One hot wire from each tool that is connected to a dust collector runs through the sensor. So he is suggesting exactly what I was – multiple “hots” through the current sensor, any one of which can turn on the DC when switched ON.

I contacted a sales rep earlier this week for an ac current sensor I found online. He thought you could only pass 1 ‘hot’ circuit wire through the current sensor at a time because it would cause a false reading.

Well, yes and no… the current sensor sense the magnetic field surrounding a wire carrying current. If the other wires are connected to load then, yes, they would rob some of the magnetic field from the current-carrying wire. But that’s not how things are usually wired. There is almost always a switch at the machine to turn it ON or OFF, so the other wires would not be connected to the load. The only time it might be a problem is if you use the breaker in the box to turn the machine ON or OFF and don’t include a switch out at the tool.

Now, another case is if you have two machines ON at one time. In this case the magnetic fields would actually add. If both machines that are ON are on the same 110 line, then all is well, you actually see the sum of both currents. If they are on opposite poles of the 220 line, then you would see the difference of the two currents and it might not be enough to trip the current sensor. That’s because US power system has two 110 volt circuits 180 degrees out of phase. Read on to the discussion below about two current sensors – that would actually solve some of these problems.

For exactly the same reason, you only run one leg of the power out to the tool through the current sensor. Let us suppose that you ran both the “hot” and “neutral” wires for a 110 volt tool through the current sensor. The hot would generate a magnetic field due to the current going out to the tool. The neutral would generate a magnetic field due to the current returning from the tool. Currents flowing in opposite directions generate magnetic fields in opposite directions and they sum to zero so the current sensor would see no current.

Since the current sensor is only detecting amperage, could both 120v and 240v ‘hot’ wires pass through the donut of the current sensor?

Yes.

I want to mount 1 current sensor on each side of the circuit breaker panel. Would I need a 2PST relay for the current sensors? If both current sensors were to trigger the relay at the same time would the relay contacts bounce?

Actually, mounting two separate current sensors, one on each 110V leg, would solve the multiple machine ON problem I mentioned above. Note that the article I referenced does not control the current going to the tool. Instead, it is used to switch power to a contactor (big ol’ relay) that actually switches the power to the dust collector. I don’t think there is a current sensor made that can handle the 20A-30A continuous required by larger DC’s. In this case I would just wire the two current sensors in parallel – either one can supply the current to the contactor coil while the other would just be off.

Now, think through your current sense and wiring in the circuit breaker panel. If you are monitoring all current through the panel by placing the current sensors on the mains and your dust collector is on one circuit in that panel, what happens? Well, you turn on a tool, which causes the dust collector to turn on. The dust collector draws current through the current sensor too. Therefore the current through the dust collector will keep it turned ON!! You will never be able to turn it off! DAMHIKT. Similarly, I don’t think you want just turning the shop lights on to run the dust collector.

Your best bet is not to monitor the mains (it seemed like that was where you were going). Instead, monitor the output of the breakers. As I mentioned above, I see no problem monitoring several circuits by running multiple wires through the current sensor. I would use two current sensors and make sure that all circuits on the same pole are on the same current sensor. Run separate breakers that are NOT run through the current sensors for the DC, lights and any tools that you do NOT want to activate the DC.

I been researching relays with built-in ‘delay off’ but most of them are rated for 15a or less. I will keep looking.

See discussion above about a separate contactor to supply the DC. The time delay relay should not really be supplying current to the DC. Instead, you use it to supply current to the contactor coil – much, much less than the current required by the DC. Think a little more… the time delay relay cannot provide power it isn’t getting. Time Delay realys that have a power OFF delay require a separate connection to the power line to properly delay power OFF.

Hope this wasn’t confusing. This post ended up a lot longer than I intended!

-- "Find out what you cannot do and then go do it!"

View jiim's profile

jiim

9 posts in 571 days


#6 posted 570 days ago

EEngineer, how can i contact you directly?

View EEngineer's profile

EEngineer

887 posts in 2244 days


#7 posted 569 days ago

I take it I confused you…

Add me to your “buddies list” Send me a message through the Lumberjocks message system.

-- "Find out what you cannot do and then go do it!"

View Cole Tallerman's profile

Cole Tallerman

391 posts in 816 days


#8 posted 569 days ago

View toolie's profile

toolie

1742 posts in 1259 days


#9 posted 569 days ago

jiim…...this will do what you want it to do, is plug and play adn the company supporting it is absolutely first rate:

http://www.ivacswitch.com/default.action?itemid=3

look at the ivac PRO system. controls 110 and 220 tools from 110 adn 220 tools. like douginva, i use the ivac switch, but the PRO series will accomodate your specifications.

-- there's a solution to every problem.......you just have to be willing to find it.

View jiim's profile

jiim

9 posts in 571 days


#10 posted 569 days ago

EEngineer, I don’t see an option to add you to the ‘buddies list’. I suspect that 5 forum posts are necessary.

View Shawn Masterson's profile

Shawn Masterson

1253 posts in 579 days


#11 posted 568 days ago

just put it outside and leave it on when you are making dust.

View crashn's profile

crashn

518 posts in 1096 days


#12 posted 568 days ago

I use the PennStateIndustries remote switched gates (called the remote commander I think). Anyways, when you open a blast gate it trips a small switch which is wired to the outlet relay. Open the port the DC comes on, close it it goes off. I have had the 110 version and it worked great. I now have the 220 version and it too works great.

-- Crashn - the only thing I make more of than sawdust is mistakes

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jiim

9 posts in 571 days


#13 posted 568 days ago

Does anyone know why I can’t add someone to the ‘buddies list’? My buddies list shows a blank page.

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TopamaxSurvivor

14722 posts in 2307 days


#14 posted 568 days ago

Maybe not enough posts yet? I’m not sure, but welcome to LJ! You can run multiple circuits through a current sensor. I have done it lots of times and never had a problem picking up any the the circuits when they energized.

If you do the mains, you will probably need to have an adjustable sensor that has a range that allows you to accommodate the lights ect.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View jiim's profile

jiim

9 posts in 571 days


#15 posted 568 days ago

I want to mount 1 current sensor on each side of the circuit breaker panel. I’ll call the current sensor on the left side of the panel sensor ‘A’ and the current sensor on the right side of the panel sensor ‘B’.

Current sensor ‘A’ has the following: (voltage + amp draw – breaker)

TableSaw 240v 24a 30a breaker
Jointer 240v
8.5a 20a breaker
BandSaw 240v@ 7a 20a breaker
Sander 240v@ 14a 20a breaker

Current sensor ‘B’ has the following: (voltage + amp draw – breaker)

BandSaw 240v 21a 30a breaker
Planer 240v
13a 20a breaker
ChopSaw 120v@ 15a 20a breaker
Router 120v@ 15a 20a breaker

  • All the above tools are own dedicated circuit with their own circuit breaker.

*Only the ‘Hot’ wire of the tool will pass through the current sensor

  • The 240v tools only have 1 hot wire running through the current sensor so technically its 120v.

Does the current sensor need to handle the highest amp rated tool or would I need to add up the amps for all tools in one current sensor in case one or more tools are turned on?

Can the 240v circuits cancel each other out if they are on the same current sensor? Can the 120v circuits cancel each other out?

Can the current sensors be wired parallel to a relay even if the current sensor input is 120v ac? The current sensor input drives the relay will starts the dust collector.

If it’s possible to wire the current sensors in parallel then it might be easier to buy 8 of the current sensors in the link below and wire them parallel to a relay.

http://www.magnelab.com/products/Current-Voltage-Sensors/split-core-ac-current-sensor-sct-0400

Sorry about the long post.

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