View Full Version : I need a dynamic brake module for a largish VFD

Forrest Addy
08-04-2005, 11:14 PM
I need a dynamic brake module for a 15 HP 230V VFD which has none on board. It's sold separately for big money by the maker. I've been looking around for used/old stock but they're scarce at my usual sources.

Most any of the stand-alone units will do provided it's capable of passing 40 - 50 Amps to the brake resistor and can be adjusted into the 375 to 400 VDC buss range.

The braking resistor is easy - a 3500 Watt (actual starting value selected for cold resistance) electric stove element running in air. I need the electronics part of a VFD's dynamic brakes.

I could cook up my own DB unit from a Schmidt trigger switching a honkin' IGFET transistor I suppose but my electronics theory while seeming crystal clear in my head hasn't worked out well in hardware recently. So I'm better off using the store-bought, already engineered stuff.

08-04-2005, 11:27 PM
You know, a dollar short and a week late. I hauled about thirty of them to the dump. (allenbradley10hp, some 20s) I may have some resistors and another in the bus. I'll look tomorrow. When I stumped my toe on them they had to go..

My whole day has been like that. Sorry..

Ever seen anyone get metal in thier eye vacuum cleaning around a mill? I have a Genie 4hp vacuum that will suck up a 3/8x3" bolt and make it whack the drum.. The hose came off the straight tube, the metal running up the tube at 30+mph hit me dead in the face, shards sticking in my cheek and one in my rt eye.. Yep whole day been like that.. 4 hours of Windows problems with Mach2 mill... Yep.. did five hours drilling/spiral machinining 2.25" holes in two pieces of alumi bar.. Yep my daugher in house alone, intercom rang, would not work, I tore the door down getting into the house only to find my wife with the button pushing it to tell me she was home..

Whole day like that.. I should've been a drunkard today I'd got more done.


08-05-2005, 09:00 AM
I have two, both have been out in the weather for a year, both are missing the covers, no documentation, one is missing components.

I can suggest me stripping the one, putting both into a tupperware style tote and shipping them to you if you want. It is a block style transistor on these. A large coil like a heater. Very large resistors.

Possibly neither is worth postage.
You can call me, email me for number.

I am not moving too fast this morning, one knee is not working too well, and my rt eye is trying to swell shut. I guess I overdid it again.

08-05-2005, 09:04 AM
And I thought, as I heaved the near new $6000 20hp 480vac inverter onto the junk mans truck. He won't get a nickel for this.

too much good stuff is just junk and clutter.