DC is 16a, rather than advertised 18a. Big deal, or not important?

[Toller]

I just bought a Penn State DC3-5XL. The web site says it has an 18a motor, but the motor says it is 16a. I have asked PS about it, but they are ignoring me.

Is this something to get upset about (stopping payment on my charge unless they do something (what?) about it) or is it a meaningless numbers game that I should ignore?

I measured the amps with nothing on it as 8a, and completely blocked as 6a. When is it 18 or 16a? I know my 17a table saw draws 4a with no load, but it draws 80a to start; while the DC motor only draws 38a to start, which makes me think it is much much smaller.

My other complain is that the power cord is is only 16 gauge. I guess that is fine if it only draws 8a, but a real problem if it ever draws the claimed

16 or 18a.

Side issue; it is a single bag unit. Can I mount it on the wall with the bag below the blower. I have asked PS a couple times about this, but they do not reply.

[Bob S.]

I too made > one < purchase from Penn State and couldn't get answers....I didn't get bite twice...

Bob S.

[Bay Area Dave]

that's no worse than when Delta began advertising that the X5 14" BS has a resilient mounted motor! After doing some repeated checking, turns out their ad department doesn't know the company's tools so well. Delta admitted it is an "error". I told them they should update their literature, but I don't think they really give a crap.

dave

Toller wrote:

[Leslie Gossett]

What is the rated HP of the motor and what was it advertised as? Some motors can deliver the same HP at a lower, or higher amperage. Motors are either rated in KW (European) or HP (USA) not in Amps. The amperage, 16 or 18 is the full load amperage rating of the motor. If the motor never actually reaches the rated amperage, that is a good thing! The 16 guage wire is probably too small even for a 16 amp motor. I wouldn't worry about the amperage if the HP is correct. I would change that cord though.

Leslie

[Toller]

It is advertised as a 1.5hp, and it says 1.5hp; but I have seen other dust collectors (HF..) that claimed to be 1.5hp, but were 12a. My understanding is that the amps is a better indication of the power than the HP, because HP can be whatever they want to say it is. If it really is a 1.5hp motor, then I have no complaint; but I can't imagine how to determine that.

I have changed the motor to 240v, so the amps are cut in half and I am not too concerned about the cord; more that it is bad sign that saved a few cents by putting an unsafe cord on it.

[Doug Miller]

That's plausible: 12A at 120V = 1440W (watts), theoretically almost 2HP. (1HP = 745.7W) A motor consuming 12A at 75% efficiency would deliver 1080W, or about 1.45HP.

Unfortunately true, especially at Sears.

16A at 120V = 1920W 1.5 HP = 1120W Getting 1.5HP out of a motor that consumes 16A is less than 60% efficiency.

Sounds like you might actually have a 2HP motor. :-)

-- Doug Miller (alphageek at milmac dot com)

How come we choose from just two people to run for president and 50 for Miss America?

[Leslie Gossett]

Were your amp readings at 120, or 240 volts?

If you compare the same HP motor from 2 different MFG's, you will find slightly different full load current ratings. The RPM of the motor will also affect the current rating. Some motors are more efficient then others, thus their current draw is more or less. Current would indicate the rated HP of a motor if the RPM and efficiency was a constant. But, there is a big margin.

Motors also have a rating which is called a service factor. This is basically an indication of how long a motor will last if it operated at maximim current for a long period of time. Machinery mfg's will take the service factor into account if the motor is marginal for the application. They could also de-rate a motor with a large service factor and label it with a higher HP then the motor mfg intended. I have seen some motors on foreign machinery which physically looked smaller then the US equivelent. I have a lathe that originally had a 1/3 HP motor, but it looked more like a

1/4 if it were a US motor.

With woodworking machinery, it seems thats HP is more of an opinion then anything else.

It doesn't sound like you got ripped-off, maybe they changed motor mfg's along the way.

[Clarke Echols]

I have found that most "specifications" in consumer woodworking tools of that type are largely bogus because they have nothing to do with the real-world shop environment. They're not even useful for comparison. Spend some time on Bill Pentz's dust-collection web site and get informed. It's at:

[Clarke Echols]

The electrical engineer contributes:

If you have a resistive load (incandescent light bulbs, for example), amps times volts = watts, and 745 watts is close enough to 1 HP. However, when you have an electric motor, the load becomes inductive due to the magnetic cores in the motor. That means that volts times amps ***AT ANY INSTANT OF TIME*** is still watts, but there is a phase shift between voltage and current; i.e., when voltage is at maximum, the current is not. The power becomes the AC line voltage times the AC line current times the

***COSINE*** of the phase angle between the two. That cosine value is known as _POWER FACTOR_, so a 5-HP motor that draws 20 amps at 240 VAC (4800 watts = 6.43 HP) and has an electro-mechanical efficiency of 80% would draw 5/0.8 HP worth of power from the line, or 6.25 HP. The phase angle would then be that angle whose cosine is 6.25/6.43, or 13.6 degrees. The cosine of 13.6 degrees is 0.97, which means the motor has a power factor of 0.97 or 97%.

This has nothing to do with duty factor which is the percentage of time the motor can operate safely at full power at a given ambient air temperature.

Clarke