Before anyone thinks that I am totally off my rocker, understand that I am of the viewpoint that this cannot happen....
I currently have a single customer, at a single site, that has approximately (14) Altivar 61 drives. He has been reporting that parameters are changing by themselves. The parameters in question range from accel and decal values, hi and low speed settings to motor faceplate values. Has anyone run across this happening without human intervention?
Any input would be greatly appreciated.
I have seen some very strange things myself during my lifetime. Are these powered from the same source? If they do not have at least a correctly sized power reactor at the power input terminals for each, there may be harmonics passing all the way to the drives' memory causing havoc.
The drives must also be apart from each other per the manufacturer suggestion, usually found in the installation manual. Same thing if the power wires are shared by DC drives and other harmonic generating devices. Look for ground loops with shielded cable signals, too.
I hope this helps.
It's been a long time since I went to Schneider's "Drives University", but as I recall on the Altivar 71, you had to specifically SAVE any changes you made when you were done making them. I'm sure the 61 is the same, they are based on the same Toshiba / Schneider JV technology.
That meant the memory went from the RAM "working memory" into an EEPROM for permanent (non-volatile) storage. Then every time the drive is powered up, the settings are read from the EEPROM back into the RAM for execution, saving the EEPROM from being accessed too often (EEPROM has a finite number of read/write cycles). If not saved to the EEPROM, settings you make reside only in RAM and still execute fine, but the first time the drive is powered down, those changes are lost and the drive reverts to whatever was last uploaded into its EEPROM.