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5hp Motor Slowing Question(Wood Shaper)


William_IV

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Hello

 

i'm just becoming familiar with a new 5hp single phase wood shaper. I'm curious about how the motor is slowed. When I shut off the machine the motor RPM's decrease smooth and at a steady rate. When the rpms get down to around 500rpm (From 7,000) the motor makes a soft click, there is a weird vibration. and then the motor comes to a complete stop. I'm wondering if i should be concerned about the vibration. Also i'm curious what causes this sudden slow down. Is this a feature that is built in to the motor or is this a feature of the attached motor starter, or Reversing switch. I'd be happy if any of you engineers could enlighten a curious woodworker?

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That steady decrease is just natural deceleration. The "click" you hear is probably a resistance or DC injection brake coming on at lower speeds. A centrifugal switch on the motor either drops a resistor into the motor winding circuit to bleed off any residual energy as heat, essentially putting a load on the motor so that it comes to a stop more quickly. Or the switch is energizing a DC power supply connected to the motor's start winding, and when you put DC onto an AC motor, it sets up a stationary magnetic field instead of a rotating one, so the motor follows the magnetic field and stops.
"He's not dead, he's just pinin' for the fjords!"
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