How much current does a Dust Collector draw?

[echnidna]

I'm thinking about getting a DC.
The correct HP rating for an electric motor is the output HP.
But some importers seem to quote the mains input rating instead, trying to fool people into thinking their product is better than the opposition.

So what I am trying to find out is the current draw of different makes of Dust Collector so I can compare the makes to each other effectively.

[Ian007]

do you want that in amps used when running??

will measure and post when done

cheers Ian :)

[echnidna]

Sorry I should have said running amps not starting current.
Much appreciated Ian

[gatiep]

Bob

I have measured the Carbatec 2 hp economy model FM300 in the Perth shop after building my cyclone. In the DC as in the shop it was running at 3.8 amps. The label on the motor rates it at 7 amps. In my cyclone it draws just a smidge over 4.95 amps. Bigger inlet and possibly a more efficient fan cage as the impeller and motor is the FM300 spare parts that I bought. The starting current from memory was about 40 amps but as that is only for a second or so it is immaterial.

Good luck
Regards
Joe

[Iain]

I am aware that in the US they stall the motor and measure the current draw just before the fire starts.
Is this cheating, of course not, but your wifes little electrolux vac is rated at 10hp.
Isn't science wonderful?

[Wood Borer]

Echidna,

For what it is worth.

As demonstrated by Gatiep, the input current varies according to the load. To compare DCs with DCs you will need to apply the same load to each machine.

The input power can be calculated by multiplying the input current by the applied voltage times the power factor (less than 1 but probably greater than 0.85). Sometimes the power factor is shown on the compliance plate of the motor.

The output power is the input power times the efficiency. The efficiency will vary between motors due to cheaper motors having higher losses in the windings or in the laminations.

- Wood Borer

[ozwinner]

How come your DC eats currents and mine only eats chips, ripped off. :( :(


Al

[Wood Borer]

Ozwinner,

You are very observant. Your Dust Collector is based on a US design whereas the others are based on a Victorian Mallee design.

The US designed DC's use integrated circuits and the dimensions are imperial. Hence your mention of chips and recently you showed a picture of two feet on your sander.

The Victorian Mallee design (Mildura region) works on currants, they found sultanas don't have the dust collecting of properties of currants but they also work very well.

- Wood Borer

[echnidna]

Wood Borer,
You are totally correct about the electrical theory.
This was the whole reason for starting the thread.
Motor efficiency and power factor considerations mean that the carbatec 2hp dust extractor cannot be a true 2hp as it is only roughly 1500W (or 1500va to be a bit more precise) it is closer to only being a true 1 hp unit and their 1hp units are probably only a true 1/2 hp.

The only reason I asked originally as line current draw in my workshop is an important consideration when working out just what machines can be turned on at the same time. I just wanted to make sure I can run a DC without overloading the mains power supply. While a 1500W motor should just be ok I think I will go for the 750W unit with lower capacity as it will be adequate for the machine that hogs most of the electricity.

gatiep
A motor driving an impeller air pump takes maximum current when it is moving the maximum volume of air. If the actual running current is far below the rated current then obviously there are frictional losses in the sysem, maybe the bags obstruct too much air (perhaps they are partly clogged) Though it seems most likely the cyclone is the main culprit. But if all works well, great!

[gatiep]

Bob,
Very interesting as both machines didn't have any restrictions other than: The DC was brand new, no inlet pipes, only the double 4" inlet. The one for my cyclone was just the cage, 6" inlet and the outlet with nothing connected
Regards
Joe

[Ian007]

Echnidna

I used to have a sparky for a buisness partner ( till he ripped me off)
who was also a tafe lectuter and he said that 740watts=1hp
therfore 1500watts is 2hp and a little bit
hope he wasnt full of cra#
as ive been working on this theory for a long while

Cheers Ian :)

[echnidna]

Ian,
746 watts equals 1 HP.
But this is only the electrical power that the motor draws from the mains.
It is not the power that the motor provides.
In fact a 750W motor will only provide somewhere around 1/2 hp of usable power.

Similar misleading representations are commonly made about speaker and amplifier outputs in the computer and Hifi fields.

So its necessary to establish how the motor power is determined by the manufacturer.
If we apply this sleight of hand to a typical car engine of say 150HP the energy provided by the petrol will be somewhere about 5-600HP if it is measured in watts and then converted to HP etc. So everyone with a commode or falcon can now rejoice that their car now has over 600HP.

[soundman]

I think you will find most woodworking equipment is rated by input power.
But I am sure ther will be exceptions.
I am disapointed about the amount information on the specification plates of most of the low to mid end gear.

I would be interested on any measured current draws of various machines people have including start currents if you have the instruments to measure same.
I have had some surprises.

[ozwinner]

I used to work in a factory years ago setting up hydraulic pumps and electric motors.
I used to set the motor to draw 15 amps while the pump was putting out 2750 psi.
If you started the motor under load, ie 2750 psi, the current draw was 120 amps, for a split second. :cool:

Al

[rev]

echnidna,

I have a 2hp motor and impeller (from economy type dc) in my cyclone, the inlet of which has been opened to 160mm diameter. At max possible airflow it runs continuously at 7.6A; the motor is rated 7.7A.