[CROSSHATCH]

Does anyone have the specs for the Braking Resistor?

I have the Sunfar C300 VFD 1.5 KW.

Is it a 400 watt power and 70 Ohm resistor or a 500 watt and 300 ohm resistor?

I have waited far too long for this upgrade but being that I'm not swapping spindles or VFD's anytime soon, it's still important for me.

Thank you.

[CROSSHATCH]

Found some old threads.

Hirudin measured 76.6 Ohms and rated for 300 watts.

SCzEngrgGroup had a 70 ohm, 260 watt unit that worked just fine.

Our recommendation for power is 400 watts but looks like we have some wiggle room.

Will be going with a 70 ohm, 300-400 watt unit.

[CROSSHATCH]

Wow. What have I been missing out on! Putting this brake on and adjusting my VFD F.10 & F.11 to 0.5 has changed my spindle! So impressed with the ramp up and braking speed.

I'm still off on my VFD Max RPM though, controlled via Centroid Acorn. At a command of 6000, VFD reads 5500. At a command of 3000 VFD reads 2750 and at a command of 750, VFD is 600. Sunfar C300 F.8 setting was originally 200 but tested up to 400 with no avail.

More to come, what an upgrade!

[upnorth]

I think there is a lot of leeway in the wattage rating of the resistor. The rating given in the manual has to cover a lot of variables. For example the VFD may be connected to a conveyer belt (or a lathe that is turning a heavy work piece) that has a lot of inertia that has to be dissipated. A milling machine has vey little inertia by comparison. All you are slowing is the motor and whatever cutter and holder is in the spindle. Not much mass. The short time it takes for the motor to come to a complete stop is not really enough to put much heat into the resistor.

[upnorth]

I had issues with the Sunfar VFD causing a lockup of the power draw bar due to electrical noise crashing the power drawbar. Under warranty and advisement from Novakon I replaced the Sunfar with a GS2 from automation direct. The automation direct VFD has been flawless. When helping recently with a cleanup I found a power resistor with a suitable resistance to use with my VFD. There were no ohm or wattage markings on the resistor. From comparison size wise I think it should be rated for about 200 watts. I'm going to give it a try.

So you know the specs for the recommended resistor are in the Sunfar manual. I googled a copy of it and it was at the very end of the manual.

[g29cc]

Crosshatch, I am interested to know more about this. I am having to fix my spindle bearings and having had this machine for over 14 years now, I ll either be upgrading it a little ( hopefully form 4000 to 6000 rpm spindle speed) or just leaving as is. Looking at VF2SS's right now. Which I know is worlds apart. But thinking of keeping this mill as a secondary op machine for simple things..... like collecting dust most likely.

Thanks
Todd