When I think about variable frequency drives (VFDs) and bypasses I am reminded of the story of the family of women cooking a ham at Christmas. The young girl notices that her mother cuts each end of the ham off before
putting the ham in the pan to cook it. She asks her mother, “why did you cut the two ends off?” The mother replies, “well that is the way my mom taught me to cook a ham.” The girl then finds her grandmother and asks her the same question, to which her grandmother responds, “that is the way my mother taught me.” The girl’s great-grandmother is still living and when the young girl asks her why she cut both ends off of the ham before she cooked it she responds, “I had a small pan and it was the only way the ham would fit.”
Bypasses have been around as long as VFDs have been used. And until recently it made sense to have a bypass on your VFD. There were two very good reasons for always having a bypass: 1) VFD’s were unreliable, had a high failure rate, were complicated to set up, and required a highly trained specialist to install, set-up, or fix your VFD. 2) A bypass was required to allow your fan or pump to run while you waited for a specialist to come and replace your variable frequency drive.
With the massive improvements in VFD quality resulting in thousands of hours of run time between failures and ease of installation and setup (see how to set up a variable frequency drive in 36 seconds) the need for VFD bypasses are few and far between. Given that most bypasses cost more than the VFD it makes much more sense to by a back up VFD that can be installed and working in the time it took your grandfather to call the VFD specialist.
If you are in Georgia or Florida you can call the Control pros at Stromquist & Company for all your variable frequency drive needs. If you are located in another part of the country one of our affiliates at Controls Group North America can be of assistance with your variable frequency drive applications.