Hey Art, hey all,
That’s what was discussed above. Power tools don’t have to comply to IEC 60034-1 so the power with which they are sold can be fantasy.
3 hp is possibly what it will draw if it is blocked in a lab. Of course it will pop a 15 A breaker then. Even if you calculate with the ancient “horsepower” unit, power tools are often sold with current measured in a load situation and multiplied with the voltage according to P = U * I. Sometimes they seem to add a hp rating of what it draws before the tool is slowed down by the mechanical load and begins to get hot. This means you pay for power consumption, not for mechanical power delivered. The electrical power draw says nothing about a motor’s mechanical power delivered (motor efficiency), means whether it is a strong or a weak power tool.
Regarding circuit breakers, if it is rated with 15 A, this means that on 120 Volts * 15 Ampères which is an electric power draw of 1.8 kW (2.4 hp), the fuse will pop.
However a spindle has to comply to IEC 60034-1 so the power rating on the nameplate should mean the mechanical power delivered at the shaft, not the electric power draw. However, the power rating on cheap chinese spindles is often wrong, as is shown in this example. This means a spindle with a correct nameplate rating of let’s say 3 hp / 2.2 kW (so this is the mechanical power delivered) will draw between 3.4 and 4.5 kVA (see here and here). That’s on the spindle input which is at the output of the VFD. Then add the VFDs loss and the power draw at the VFD input is even higher. This explains the current draw values on the two VFD nameplates for 2.2 kW (3 hp) spindles above.
Also power tools like routers are usually so-called universal motors (carbon-brush commutated series-wound motors) that have a much worse efficiency than spindles (induction motors), which means with the same mechanical power delivered, universal motors need much more power drawn than spindles, or the other way round: With a specific electrical power consumption, a spindle delivers much more mechanical power than a router. See spindle vs. router motor characteristics comparison.