People had pressured us to buy one for years. However, when we built a new house, we were able to install a central vac for a little more than half the price of a rainbow. The central vac has a huge primary filter (cyclone separator) and exhausts the rest outside. No contest in my mind.
Here's how they come up with the high horsepower numbers: You are, of course, correct in saying that if the thing really developed all that power it would blow the breaker. Anyway here goes: You know that one horsepower equals 746 watts. Okay. So, they connect huge wires directly to the motor, let's say #1 or #2 gage. They put in HUGE breakers for the test, let's say 100 or 200 amps. Now, these motors are usually series wound motors with brushes, right? Okay. So they connect the motor to a braking system and they connect a volt meter (probably a data acquisition unit these days) across the incoming line. They connect an ammeter in series with the whole thing. Now comes the fun part: They start up the motor and read the meters. Now, they slow down the series wound motor and, as they do, the reverse emf goes down, so the circuit current goes up because the net resistance to current flow is reduced by the lowering of the reverse emf. Still with me? Okay, now they continue to slow the motor down while taking readings. Remember that they are feeding this motor with HUGE wires, so the voltmeter across the motor leads is reading FULL line voltage all the time. They keep slowing the motor down with the braking system until the motor just stalls. Just as it comes to a stall, there is NO reverse emf generated and the total resistance of the motor is equal to its at-rest DC resistance. So the current goes sky-high! This, of course, blows out the whole motor, but, at this moment of this super high current, just before the motor creates fireworks, they read that current and, of course, the incoming voltage, which is still a full line value. Amps times volts equals watts. They could be seeing 30 or
40 amps or more for a few milliseconds. Depending on how much horsepower marketing wants to sell, they could come up with 10 hp or so if they can get 70 amps out of the system as it self destructs! Of course, this had absolutely NOTHING to do with vacuuming your rug, but that's how the game can be played without anyone actually having to go to jail.Ain't the capitalist system great?
Pete Stanaitis
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