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P a g e
Enable Circuit
To set up your VFD correctly, you only want power supplied to it while your control is enabled. Use the 24V
enable signal (24-EN) from the breakout board, a 24V relay, and a contactor as shown below. If you purchased a
drive enclosure, your enable circuit is already set up.
If your VFD is rated for your spindle motor (i.e. 3Hp VFD with a 3Hp motor), then anything above 3Hp must use 3
phase power. The blue dashed line in the diagram below shows the 3 phase wire.
Figure 2 Enable Circuit
When the machine is enabled, the 24-EN signal turns on. This turns on RC2 which then connects 230 VAC to the
coil of RC1. RC1 then turns on the power to the VFD. You can use the same enable circuit for your servo drives.
