G0602 Reverse Tumbler

GunsOfNavarone said:
I appreciate the input and the chart. I know it's difficult around here sometimes as many people are very seasoned here and they're here for like minded people. Then there are others (like myself) that are here to learn from the aforementioned. Some are very happy to give/shape/teach, you guys are very much appreciated.
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We're all pretty much here to help.

GunsOfNavarone said:
I know this isn't the place to pose this question, but I'm pretty sure I can (capacitors?) To my VFD for braking purposes, this would be huge for the whole "threading excitement" you spoke of.
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I'm not sure I understand your question ... but it appears you're asking whether it's OK to put a capacitor across the "braking resistor" terminals of a VFD, instead of an actual resistor. If so, I'd recommend against it. Don't have a perfect understanding of how a VFD works, so I may be a bit wrong. But as far as I can tell, the braking function electronically connects the resistor across motor windings (which are acting as a generator).

Resistors and capacitors will act differently. My own VFDs (Teco FM-50) specify 100 ohm braking resistors. When first connected, the "resistance" offered by a capacitor is near zero (acting pretty much like a short circuit). It then rises to near infinity as it charges up to a voltage equal to the "driving" voltage from the motor. The initial near-zero resistance might be too low (and the inrush current too high) for the VFD circuitry to handle. Then you end up with a bunch of energy stored in the capacitor, which must be dissipated somehow. A power resistor, in contrast, will present a constant, known resistance to the VFD's circuitry. It dissipates the energy by producing heat.

If I absolutely had to substitute for a braking resistor on a VFD, my first choice would be a small space heater ... basically a large resistor designed to produce heat. I'd start be measuring the resistance across the AC plug, to verify that it's somewhere near the specified value. A large light bulb (say 100 watts) also comes to mind ... but the "cold" resistance of a light bulb filament is very low, so it might not be suitable.

Your best bet is to save up your pennies and buy an actual braking resistor. Here's one for just over $15:

uxcell 150W 100 Ohm Aluminum Housing Wirewound Braking Resistor: Amazon.com: Industrial & Scientific

Shop Amazon for uxcell 150W 100 Ohm Aluminum Housing Wirewound Braking Resistor and find millions of items, delivered faster than ever.
www.amazon.com
 
Thanks Hman. My bad, I assumed the braking stored energy from motor in a capacitor. I have the TECO L510. I honestly don't even know where the resistor or brake is wired in, just something the whole threading conversation brought up for me. I really want the braking if it's even possible with my setup, but haven't found much helpful information on the subject.
 
My FM-50 has two sets of terminals ... a set of "small" ones, where you connect the speed pot, etc., and a set of large ones for input power and the motor connection. The braking resistor is wired between the P and R terminals on this strip. Don't know if a L510 has the same setup.

As I recall, the FM-50 manual was a bit sparse when it came to documenting braking resistor installation. I think I phoned them. The info I got was that there's no need to "tell the software" that the resistor has been installed. But with it in place, you can set the stop time a lot shorter. I have 2HP and 3HP motors and use 0.5 seconds on both.
 
Come to find out, the 230v tecos don't have the p/br connection for brake, only the 430v units. Guess that's not an option for my setup. I guess I won't miss what I never had.
 
That's interesting UB27...not sure it is meant to be used as much as you would threading, & it seems you need to clear it out after using, but maybe something to play with & see what it can do. I am curious, if a resistor brake is so large, how would this even work with the overall compact size of the L510.... Hmmmm....
 
I don't have a 3ph motor on my lathe. Using a KBCC125R with a 2.5hp dc motor instead. The brake resistor is approx 5.5" long on that.
 
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