Originally posted by: Jeff7
Sorry, 3 HP = 2,237.09961 watts.
It's funny how all these ratings get skewed. In pro audio we have amplifiers that can put out 4000 watts per channel into 4 ohms and run on a 120V 15A circuit. How is that? Well music is never a continuous tone. If the program demands the power it will come from the outlet (and often trip the breaker) hence one has to be careful if their distro is limited to 15A for this example.
With a blender it's possible to have a motor that can produce a peak of 3HP and run on a common 15A 120VAC circuit as well. The most common motor used is the universal motor that has a very high speed (a dremel moto tool is based on a universal motor) and speed that will sag under load (this depends on the motor controller). While the blender on frappe may freewheel at only 3.0A it will draw 5-10 times that when a load is dumped (ice cubes while making a smoothie). Normal fusing/circuit breakers will allow these types of momentary overcurrents to pass freely and the actual hp rating can indeed reach over 3hp in such given circumstances.
Where the blender motor vs. pro amp example varies is under a continuous load the windings in the blender motor will overheat. The amp (if the circuit allows) will produce a high output sine wave at its terminals until either the speaker voice coil
melts down or the amp's output transistor heatsink grows too warm and thermal protection interacts cutting off the output.
The blender most likely has a current monitor to protect the motor windings, commutator, and brushes too. If there's not too much isolation between the motor controller and the supply circuit and the supply circuit is protected with an arc fault circuit interrupter it may trip from excessive brush to commutator sparking. If the blender is very sophisticated it may use a polyphase motor with cycloconverter drives. Those are another discussion all by themselves.
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