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Old 06-27-08, 10:43 AM   #1
phantomcow2
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Braking an AC motor

I have an application which requires the use of a 1HP AC motor coupled to a fairly heavy load. A problem I have is that when I turn off the motor, the AC motor continues to freewheel for several seconds. Is there any electrical way that I can stop -- or at least reduce -- the freewheeling of this motor?
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Old 06-27-08, 10:47 AM   #2
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Also, adding a VFD is not an option. Cheap, or as cheap as can be, is the name of the game.
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Old 06-27-08, 10:59 AM   #3
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They make brake motors and electric brakes for motors. Neither of which are very cheap. Google brake motors and try to find the HP you need.
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Old 06-27-08, 11:32 AM   #4
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have you tried a servo motor?
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Old 06-27-08, 12:27 PM   #5
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A servo motor is a good idea, but I forgot to add one condition: The existing motor must be used. This motor has all the mounting hardware machined to fit it already.
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Old 06-27-08, 01:30 PM   #6
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use a servo to brake it.
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Old 06-27-08, 01:33 PM   #7
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Perhaps you can make a brake which would be selinoide (sp?) operated when you turn off the motor?

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Old 06-27-08, 01:50 PM   #8
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Perhaps you can make a brake which would be selinoide (sp?) operated when you turn off the motor?

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Old 06-27-08, 02:34 PM   #9
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Friction brake motors are common. a control circuit energizes a magnetic coil to open the brake as the motor runs.
http://www.stearnsbrake.net/
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Old 06-27-08, 02:41 PM   #10
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Or this?
http://news.thomasnet.com/fullstory/10801
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Old 06-27-08, 05:10 PM   #11
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HELLO???? Avid juicy ultimate + actuator. Plus you can buy two so you have one for.... "backup".
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Old 06-27-08, 09:53 PM   #12
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Single phase or 3 phase?
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Old 06-28-08, 07:27 AM   #13
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Single phase
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Old 06-28-08, 10:41 AM   #14
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There are a number of manufacturers such as Dings, Stearns, and Warner Electric who make electrically operated models in both DC and AC. One popular style is to place the brake on the NonDrive end of a motor, however this does require that the motor was designed to accept an aftermarket brake. It may be possible that the motor manufacturer may already have a brake "kit" for your specific motor.

Another brake design has a C-Face machined on both sides of the brake and the motor is placed onto the DriveEnd C-Face of the motor sandwiching the brake between the motor and machine. These C-Face dimensions follow industry standards from Nema (National Electrical Manufactures Assoscation). You mentioned machining already done to mount the motor, I can only assume that this is a Nema C-face.

Your easiest bet is to use what's called a failsafe brake, electrical power to the brake holds the brake off. Wire in with the motor, this way when you power the motor, the brake comes off. Disconnect the motor from power and the brake comes on.
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