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View Full Version : Adjustable current limit in VFD?


bcammack
09-08-2008, 04:59 PM
Is there any such programmable variable in the Delta VFD where I can make it shut the heck down if a threshold amperage is exceeded?

I am dealing with some employees that would rather kill a $400 set of precision bearings in a 5HP Colombo spindle by ignoring my instructions not to exceed 14 amps just so they don't have to route out and finish a vanity top by hand.

I'd like to simply go with the "manage your people" concept, except I have no control of that.
rhfurniture
09-09-2008, 03:44 AM
On my Hitachi it is B012 and can be set at between 20 and 120 percent of the inverter current rating. It also has an overload restriction setting (B021 - B023) that will slow the motor down if it goes above a set current draw. But do you really want the thing to stop mid cut?
R.
bcammack
09-09-2008, 09:19 AM
Thanks, Ralph. I guess this warrants further investigation.
rhfurniture
09-09-2008, 09:55 AM
What there is on mine is an output that puts out a voltage that is related to the current draw (I have an amp-meter display on it), that you could set up with some no doubt simple electronics to trigger an AIR RAID SIIIRRREEEEEN (or a shopbot estop) when 14 amps are exceeded...
bcammack
09-09-2008, 03:54 PM
Called PDS and asked.

For a B-series Delta VFD, there is an Over-torque setting that can range from 30% to 200% of the unit's rated capacity. Their tech recommended I start at 75% and adjust from there via trial and error.

Once we get a fresh set of bearings in the spindle, I'll play with it and post the results with some more "how-to" detail. (I loaned the VFD manual to our maintenance guy and haven't been able to compare my notes with the documentation for intelligent discussion about the hows of it all.)

Most interesting was that the tech said in ten years, nobody had ever asked that question before and he was going to play with it himself because he has more than one customer in the same boat as we are regarding unskilled production operators and timely tool changeout.
lukejenson
09-08-2009, 02:02 PM
I'd also suggest hitachi vfds.

http://www.ctiautomation.net/Hitachi-VFD-Drives.htm