I have been having problems with my VFDs on my property ever since I can remember, So ive been swapping them out 1 at a time for the last year or so. Ive been swapping out the Toshiba/E3 drive which came with the unit originally and replacing them with the new ABB/ACH550-UH units. I have replaced 4 VFDs to date.
Its 6:00am monday morning
and I'm going through my morning walkthrough and low and behold I have a Rooftop Unit down. Now im a in house guy so I dont get the excitement you service guys get on a daily basis so I am actually thrilled about this because it gives me a chance to do what I do best "troubleshoot and repair". The units not running so i check the obvious first, Yup got Power" onto the next, "Hmm contactor closed" To the VFD I go and there it is, my brand new ABB drive Installed less the 3 months ago is giving me a "phase fail" alarm. So I clear the alarm to see what happens, The RTU starts ramping up but I'm noticing the motor is vibrating violently. I mean this thing was rockin, VFD was at full speed/60hz and just shimmying the motor all over the place. Well I figured I had broken bearing, warped shaft or blower wheel. Well I couldnt be more wrong, long story short (sort of) I disconnected the VFD and wired the fan Direct from the contactor and walahh!! No more vibration, motor ran smooth. I called back Carrier and told them the situation they came to my building to troubleshoot the VFD and condemed the drive. No problem, I guess you could get a bad part anywhere but not a month later one of the very same drives starts doing the very same thing. Motor vibrating violently when connected to the drive but when the drive is removed from the circiut, the motor runs smooth no problems.
My questions to all you genuises out there, Have you ever seen electricity have such an impact on a motor and why the hell are my brand new VFDs dying on me one at a time!?
Its 6:00am monday morning
My questions to all you genuises out there, Have you ever seen electricity have such an impact on a motor and why the hell are my brand new VFDs dying on me one at a time!?