On Thu, 2008-06-05 at 00:18 -0500, Jon Elson wrote: > I don't think there is truly ONE way to do things. You pretty > much have to use safety-rated controls from Pilz, Crouzet, > Schaffner, Faulhaber, etc., and then set them up so they can > function correctly to stop motion, even after a component failure.
Yes. In fact, that's what I've learned so far! The most recent control I've built uses a commercial safety relay in the estop circuit, as well as an EN418 qualified (anti tease, positive acting) estop button. There's also some redundancy of power control elements and monitoring circuits that prevent resetting estop if a contact has welded closed. What I'm interested in is what I've missed! I learned all those techniques from manufacturers literature that refers to these standards, but I've never actually seen the standards documents themselves, and I'd like to... <...> > pretty expensive. Then, you get into calibrated wideband > antennas, and on and on. Finally, you have to test every > different configuration, so you generally have to test each > specific installation, if you are doing one-off machine retrofits. All true of course. I guess I put too much emphasis on the "accuracy" part of my request. I don't doubt that elaborate test equipment and facilities would be required to certify performance to a particular standard or spec. The most basic test for RFI is to tune around the AM radio band on a receiver with the antenna close to the equipment under consideration, listening for changes in the level of "static". I'm just hoping to improve on this; to take it to the next step. Maybe build some sort of "hobby standard" wide band RFI detector useful for comparison purposes, rather than a calibrated measurement instrument. For example, if I put a ferrite bead on a cable, did it help reduce the RFI, or was there no change at all? Right now, I'm operating in the dark, installing filters, chokes and beads in an anticipatory, prophylactic way ;). What I need is a relative indicator to detect electrical interference, locate the source, and compare the effect of different mitigation methods. > Most machine tool controls have had totally uncontrolled > emissions, because they were mostly exempt as heavy industrial > equipment. Note the lack of output filters on most PWM servo amps. Your own being an exception to this! > Devices to inject disturbances into the line and equipment > chassis are not as bad as the spectum analyzer type gear, and > you can even make much of this yourself, like with auto ignition > coils and pulser circuits. I did make a vibrating relay type noise generator which helped recreate an intermittent problem with a spindle speed control board. Once they were able to reliably produce the problem, the manufacturer of the board was able to add hardware filtering and do some software modifications that eliminated the problem. I want to come up with some reference designs for these types of noise generators so that susceptibility comparisons can be made. Thanks, Matt ] ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
