I'd be wondering if that is a 3hp induction motor or a universal motor.
HUGE difference between the two. I laugh anytime I see a shop vac being sold
as a 7 1/2 hp machine. Then cry when someone believes it.
There are some exceptions to this; bench grinder, horizontal
mortising/boring machine, hollow chisel mortiser, dust collector...
> If it's *NOISY* it's a universal motor.
This one is pretty much guaranteed. Wailing like a banshee means universal.
On Sun, 7 Sep 2008 10:03:15 -0500, "The Davenport's"
Not really. Power is still Amps X Voltage (with phase angle considered
for AC) regardless of whether it's a universal or induction motor.
The difference is in the marketing department of the manufacturer's
sales organization. They like to claim as much power as they can get
away with for their shop-vac. So, most of that hype comes from using
the amperage drawn by the motor with the rotor locked - the absolute
maximum the motor will draw. That amperage multiplied by the supply
voltage gives a pseudo wattage value that can be converted to
Horsepower at the rate of 746 watts per HP.
Now that's the power consumed (or in marketing terms, "Developed") by
the motor under conditions in which it is actually producing no power
at all. Mechanical Power = Torque X rotational velocity (with the
proper units). So with rotation = 0, Power = 0.
That marketing approach to power ratings seems to be most often found
in small universal motor applications, but I've also seen applications
using induction motors emblazoned with such things a "7 HP Developed"
and in much smaller lettering "3 HP Running".
But, it's all marketing hype, not something intrinsic to universal vs
Sorta, except the audiophools are even more creative. They take the
open circuit voltage times the short circuit current and give it a
technical term lie "music power". If they are really creative
they'll call it "RMS music power" or some other nonsensical term.
It would be like measuring the rotor torque close to stall times the
On Sat, 6 Sep 2008 16:14:05 -0700 (PDT), DejaVoodoo
Keep in mind that you may need 5 HP+ when a DC and air filters are
running. A motor can be replaced in a table saw--I'd suspect a belt
drive type is easier to swap. In my opinion, table saw power is less
important than a large flat cast-iron table, a quality precision
fence, and a sharp blade. If your 1.75 HP is not constantly bogging
down I doubt you need 3 HP.
It doesn't "smooth out" the power but as others have mentioned, it
will give you somewhat more power (and keep the motor cooler)
because there is less drop in the wires (all assuming the same sized
It *can*, but likely won't. 1HP ~= 750W, assuming 100% efficiency.
A 120V 30A circuit might be able to supply a 3HP motor, but it would
be a waste of copper (#10 wire required). A 220V 20A circuit is
almost always simpler and cheaper, all around.
Don't worry. Be happy.
It likely can be replaced, but since you're happy with the saw now
there is little chance the "upgrade" would be worth the expense.
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