[How do I?] MetalOxide Variator as braking resistor?

Dynamic Braking Resistors get F#@ing hot and are usually mounted inside a cage on top of the control cabinet.
Regardless of the manufacturer tech support will help you size DBR'S correctly.
They turn electrical current into heat.
I recently commissioned a dual-capstan setup on a cable extrusion line; it was set up like so: unwinder machine (large spool >8ft dia., bare cable) -> capstan #1 -> extruder (melts a jacket onto the cable) -> water cooling trough -> capstan #2 -> winder machine. The reason for two capstans was to establish a desired amount of tension on the cable during the process, I assume something to do with "pre-load/pre-stress" similar to concrete bridge sections.

For that application capstan #2 (after the cooling trough) required no braking resistor at all but capstan #1 operated continuously in braking/regen mode and required a massive amount of braking resistor capacity. I actually made up a bank of braking resistors and installed an external braking chopper because the drive's internal braking transistor wasn't up to the task. If I had just installed a single resistor, even the largest one the drive was rated for, it would have glowed white hot and fused open in probably under a minute. I could have installed a single resistor on capstan #2, no problem. It wouldn't glow white, red, or orange, ever. Current would never flow in it because what little braking that capstan does, would be absorbed by the DC bus capacitors. It would sit there collecting dust, and become a home for spiders.

I mention this to highlight the fact that not all applications are the same. These two capstans were identical but given the way they were used, had very different braking requirements. Not every machine has or needs a braking resistor, and not every machine which has one, ever gets hot enough to cause problems. I have installed braking resistors inside control cabinets (ceramic encapsulated types) and I have installed them on top (ventilated wire-wound types) depending on the application and amount of expected braking energy.

There is a bit of research and math required to determine which scenario is appropriate and I agree with your advice to consult the manufacturer if in doubt.
 
Yes, very good point! Loco braking resistors are similar, with blazing heat...

Sent from my SM-G715A using Tapatalk
 
Yes, very good point! Loco braking resistors are similar, with blazing heat...

Sent from my SM-G715A using Tapatalk
I would love to see that. Trains are fascinating but I've never had a chance to see under a train's skirt. Closest I've seen to that is probably the draw works on an offshore oil rig. IIRC it had (4) 1,000HP motors and the braking resistors on it would shriek like a raped alien when the top drive was going down.
 
MKSJ,
Thanks a million for all your help.
I finally have a working lathe. I still havent finished tuning. But resetting and retuning and using the settings you suggested like 1.5KW and 4.5A have the machine cutting without complaining. So far neither VFD nor lathe get very hot, but then again I haven't pushed too hard. No more E05 so far, and this is even without resistor. Still doing updates to control and resistor.
Thanks again
 
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