Let's unravel HVACR complexities with Tim R. Skell!
Our expert, Tim R. Skell, spent almost 3 years sharing his expertise in the #FunFactFriday series on LinkedIn. Now, we are giving him a forum to exchange news, knowledge, and passion for HVACR technologies in the new ABB column.
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Did you know there is an ACH580 parameter (97.135) that shows how much ripple is on the DC bus voltage? Unless you are a big ol’ VSD geek like me, you probably just thought “So what?” or “How does that help me?”
This parameter helps out with two types of tasks:
- Provides an indication of the quality of the input line voltage.
- Can offer an early indication of capacitor failure in the drive.
For Task 1, you can identify an unbalanced input voltage, without needing to get out your meter! This can be loose connections, blown fuses, bad power, etc. As you have seen from past posts, I’m a big advocate of doing as much preliminary troubleshooting as possible with the “cover-on, door-closed” for Safety reasons.
For Task 2, use BACnet to trend ripple data over the building automation system (BAS). If you see the value creeping up over time (at comparable loads), check the power quality – and if that is good, then it might be an indication the capacitors going bad and you should contact ABB.
In the pics above, both at full speed/load, the drive on the left is looking good while the drive on the right would cause me to stop and investigate, also in the ACQ580!
ACH580 drives family 
ACQ580 drives family
