# Dust collector load.



## Lanny0134 (Apr 21, 2012)

I recently upgraded dust collectors from a craftsman one bag to a the v2000 from oneida. After looking into putting a canister on the craftsman for a while this cyclone came up on Craigslist for around the value of the old dust collector and the price of a new filter. The catch is I have to run it on my lone 30 amp 220 circuit. My father is an electrical engineer so I have run everything by him as far as safe loading and he says I'm good to run the collector plus one other piece of equipment. 

My question is does the collector pull more amps with more gates open or closed? The little info I found online seemed to indicate that more airflow =more load but this was in reference to professional sized collectors. Does this hold true for smaller units as well?


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## Fred Hargis (Apr 28, 2012)

It will pull more load with the gates open. In fact, the test I had for my Oneida was to check the load with all the gates open to determine max draw. What you might want to check is the start up load, DC's can pull a lot of juice while they are spinning that impeller up to speed.


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## WillemJM (Aug 18, 2011)

Fred is correct, so is your dad. You will be fine with a 30A breaker, you should be able to run two of those off the breaker.

Air Power (kW) = Pressure (kPa) x volume (M3/s)

So, it follows if there is no volume or air flow, the amp pull would only be what is necessary to spin the impeller against bearing friction, equating roughly to efficiency loss.


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## Dave Paine (May 30, 2012)

Good question. Since I am able to measure amps on my 120V DC I decided to take some measurements.

Nominal 1 1/2HP motor. Nameplate states 11 amp at full load.

Load with all blast gates closed = 4.03 amp
Load with closest blast gate open = 6.75 amp
Load with first + next further blast gate open = 7.15 amp
Load with first two + furthest blast gate open = 7.35 amp

This shows my duct work/fittings is constraining the airflow and load.

I would say Motor Power is proportional to static pressure x flow, but not so simple an equation.

There is airflow with a blast gate closed, it just is dead headed, so the air is not going anywhere, just cycling within the blower. 

There is more resistance to rotating the blower with the blast gate closed than if the motor were disconnected and run at zero load. Spinning the air in the blower consumes a lot more energy than just the losses in the bearings of the motor.


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## WillemJM (Aug 18, 2011)

Dave Paine said:


> I would say Motor Power is proportional to static pressure x flow, but not so simple an equation.


Note, equation posted refers to "Air Power" not motor power.

From experience in the field, at full load of the system we would expect around 60-70% efficiency for the woodworking units discussed here the no load amps on the motor only would depend on how well the motor was built, Eddy-current losses etc. As the duty moves away from the optimum point on the fan curve, the efficiency will drop.

In short, to OP, the more blast gates you close, the less amps drawn, follow Daves post above.


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