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Tip # 1 for VFD outdoor enclosure ratings


When specifying a drive for outdoor applications it is always wise to make sure the manufacturer has designated their design as “Outdoor” or “direct sunlight” capable. If the unit was indoor applications only, it may not have enough UV protectant in the molded plastic case to handle years of UV abuse. 

Tip # 2 for SMVector series VFD from AC TECH LENZEactechkeypad_square

Remote Keypads – When installing a remote keypad kit for the SMV series of drives. Some of the wording on the instruction manual is not very clear.  It will state to “Assert” the # 1 terminal on the digital input block. What this actually means is that a jumper wire is to be installed to allow a ‘run’ condition to be conducted by remote keypad.

Tip # 3 Sizing a 3 phase VFD to accept single phase 230/460V input line voltage


The general rule of thumb has been to utilize the motor’s rated FLA and multiply by 1.73 (square root of 3). This was a calculation that worked well when VFD’s were overbuilt in the past.  As cost reductions are always on the move with a lot of manufacturers, we’ve seen the industry transition from this method to adding a little more safety factor in calculation.  The industry has moved on to using the motor FLA x 2 to provide the added safety factor.   Some are even using FLA x 2.15 for the needed output current with the really inexpensive drives.  This in the industry is called de-rating a VFD. Always keep in mind the ambient temperature and elevation in the selection process and be sure to follow all manufacturers instruction manuals for reference.

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