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+-- Thread: Your 3 HP DC's power consumption? (/showthread.php?tid=7347874)
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Your 3 HP DC's power consumption? - SpiderDave - 04-24-2019
Surely this has come up, but I couldn't find much. I have a 3HP dust collector and nothing to compare to, as this is my first. I was wondering from those of you who have dust collectors out there. If you don't mind,... what DC unit do you have, how many hrs average does it run a month and what would you guesstimate is your cost of running it? I know that might be a difficult question to answer considering there are other tools and lights etc running too, so how would you know? Maybe if you already all of that previously and either didn't have a DC or worked outside instead before you had any dust collection? Did you notice much of a difference in your electricity bill when you started using a dust collection system later on? BTW, isn't it over all cheaper to run 220 than 120?
RE: Your 3 HP DC's power consumption? - jteneyck - 04-24-2019
(04-24-2019, 04:06 PM)SpiderDave Wrote: Surely this has come up, but I couldn't find much. I have a 3HP dust collector and nothing to compare to, as this is my first. I was wondering from those of you who have dust collectors out there. If you don't mind,... what DC unit do you have, how many hrs average does it run a month and what would you guesstimate is your cost of running it? I know that might be a difficult question to answer considering there are other tools and lights etc running too, so how would you know? Maybe if you already all of that previously and either didn't have a DC or worked outside instead before you had any dust collection? Did you notice much of a difference in your electricity bill when you started using a dust collection system later on? BTW, isn't it over all cheaper to run 220 than 120?
Rather than ask why don't you put an ammeter on one of the motor leads and measure how many amps it draws with one, two, etc. blast gates open? That will tell you how many watts it consumes/hour. Then put an hour meter on it, one that can be reset to zero would be even better. Now you have your answer at whatever frequency you like. Or spring for the gusto and put a watt meter on it.
John
RE: Your 3 HP DC's power consumption? - DFJarvie - 04-24-2019
I run mine when I use the TS, drum sander etc. if these tools are on more than 5 minutes per hour it’s a lot. The TS will probably draw as much power as the DC since both are 3 hp.
I am in my shop around 18 hrs per week and I don’t notice any increase in my electric bill. It’s over the winter when I have the electric heater on I see the electric bill increase around 30 bucks a months. That’s drawing 21 amps.
RE: Your 3 HP DC's power consumption? - fredhargis - 04-25-2019
Mines a 5 HP, but seldom draws more than 12 amps or so. Even so, it doesn't cost enough to notice it on my electric bill.
RE: Your 3 HP DC's power consumption? - TDKPE - 04-25-2019
If you want to keep a running tab on watt-hour usage, you can buy a retired kWh meter like the one on the side of your house for around $25, but you'll have to buy the socket for $25-50 to plug it into, also.
https://www.ebay.com/p/Ge-Electric-Watthour-Meter-kwh-Type-I70s-I-70s-EZ-Read-240v-200a/1276146334?iid=190729189781&chn=ps
https://www.homedepot.com/p/Square-D-100-Amp-Ringless-Horn-Bypass-Overhead-or-Underground-Meter-Socket-UHRS111C/100141763?cm_mmc=Shopping%7CG%7CVF%7CD27E%7C27-8_CIRCUIT_PROTECT._DEVICES%7CNA%7CPLA%7c71700000033149223%7c58700003867184469%7c92700031085877420&gclid=EAIaIQobChMIzqfVjpDr4QIVCYbICh3kcQTjEAQYAiABEgK44vD_BwE&gclsrc=aw.ds
There are other ways to do that too, using an inductive coil and a small electronic meter. Or a clamp-on ammeter, which every shop should have, but they're less accurate for estimating cost to operate when measuring motor loads, since they just measure total current and can't separate the real power part from the reactive power part (they just measure amperage) like real electric meters do. But they do accurately total current, which is important to the wiring and switchgear and such.
BUT, even if you did measure wattage accurately, I think you'd find even a large DC blower uses relatively little power unless it's running under load all day. A 3 hp motor running under full load for an hour, assuming common efficiency of 80%, and using $0.10/kWh (my marginal rate, including delivery and all taxes), would cost 28 cents per hour to run. That's running under full load, which any DC blower is highly unlikely to do unless it's part of a highly engineered system in a production environment, and electric consumption goes down as the air is restricted and the motor load goes down, almost to zero when motor load is zero.*
As to 120 vs 240V - there will be no difference in cost to operate. Dual-voltage motors have two windings internally, and they're connected in series for 240V operation, or parallel for 120V operation, so either way, each winding 'sees' 120V across it. And your meter on the outside of the house doesn't care if you draw 15A from both hot legs (15A in on one leg and back to the transformer on the other), or 30A from one leg (with the neutral carrying the 30A to complete the circuit) - it still measures wattage, and keeps a running total against time, so either way will spin the meter just as fast.
*At zero load, even though a clamp-on ammeter will read something like 1/3 to 1/2 of the nameplate rated current, most of that current is reactive, and doesn't measure on the utility's residential electric meter on your house, so you don't get billed for that. You'll only pay for the little portion of that current that's making the windings warm and moving air for cooling and making sound. A Kill A Watt actually will measure wattage accurately, and also show volt-amps and power factor and can keep a running total of actual watt-hours (Wh) consumed and even cost when you input your marginal rate, but it's too small to handle a 3 hp motor, and can only work with 120V loads regardless of size.
RE: Your 3 HP DC's power consumption? - SpiderDave - 04-25-2019
I do have a meter, but my DC Unit's not installed yet. I almost have everything now to get going on it. I've been hesitant about having something that big running so much and driving my electricity bill up, but I wouldn't know since this is my first DC. I was hoping to put my mind to rest if I could get a ballpark idea by hearing what other people's experiences were? I'm at a point where I could make changes now to accommodate a smaller system and change the build. But if it's NOT going to make that much difference in my bill, then I won't. But I would, if it was necessary to avoid paying out the nose for it to run for long periods every day. I'm just having a bad case of jitters since so many other set backs have happened along the way on this project. It's one of the main and important pieces of my shop, so it's worth worrying about where I normally wouldn't. But it's sounding from what you all wrote, like it won't be that bad at all.
I've gotten a few surprise electric bills before that where like 'Whhaaaat!!!?" "Are you kidding me?!" And those times I hadn't done very much at all in the shop that month. If I get a higher one this time I'd just like to be able to rationalize it by saying, "Well that's how it goes I did what I could and I can't lower the bill without going to ridiculous lengths,.. so I'll live with it."
Thank you all!
RE: Your 3 HP DC's power consumption? - jteneyck - 04-25-2019
You will save very little electricity by downsizing the DC, but you will regret doing so by its lower performance. To help ease your mind, I'm retired and often put in over 100 hours/month in my shop. 5HP BS, 3HP drum sander, 4HP J/P, 1.5 HP TS, 60 gal compressor which drives my spray gun, etc., all connected to a 2 HP DC (which I wish were larger). On most projects every machine gets used, a lot. The difference between a high usage month and one where I use it very little/not at all might be a max. of $20 in my electricity bill. Of that, the DC is only a fraction.
Buy one less latte a month and you can run your DC as much as you want.
John
RE: Your 3 HP DC's power consumption? - Alan S - 04-25-2019
You got an expert answer from TDKPE. All I want to add is that the motor is closest to a no-load condition (where it consumes almost no power) when the blast gates are all closed.
RE: Your 3 HP DC's power consumption? - SpiderDave - 04-26-2019
(04-25-2019, 09:46 PM)Alan S Wrote: You got an expert answer from TDKPE. All I want to add is that the motor is closest to a no-load condition (where it consumes almost no power) when the blast gates are all closed.
I second that!
![[Image: thumbsup.png]](https://forums.woodnet.net/images/icons/thumbsup.png){kind=icon}
Thank you everybody, I'm gona get on it and move forward without looking back. I appreciate you 'all' contributing to putting my mind at ease here and sticking though it with me until I got it through my thick head.
![[Image: biggrin.png]](https://forums.woodnet.net/images/icons/biggrin.png){kind=icon}
I'm not sure what I would do without the help I've gotten here.
RE: Your 3 HP DC's power consumption? - Stwood_ - 05-01-2019
4 HP
All 6" main piping, in the floor. I also blow it all outside. No bags/barrels to contend with.
Never noticed/tracked collector cost. Have no interest in knowing. Gotta use it, use it.
I'm no longer in business and it doesn't run every day now, just occasionally.