The contactor that PMDX sells is typically used as the mains power switch
device for the spindle and axis drives of large machines. It may also be
used to switch a spindle motor on and off when a VFD is not used. There
is no reason to use a contactor between a VFD and the spindle. Indeed
some older VFDs may be harmed by doing this. The VFD has control terminals
that are activated by light duty contacts or the outputs of a spindle control
such as the PMDX-107 or PMDX-407.
An example of using a contactor as a mains power switch together with a
"charge pump" safety circuit is shown here:
http://www.pmdx.com/Doc/AN003_MachinePower_03.pdfThis example is for a PMDX-125/126 running from a parallel port. The
"charge pump" is used to prevent errant operation of the parallel port
during power up of the PC from activating the machine. There is no need
for a "charge pump" with intelligent controls such as our SmartBOB, but
they still offer such a signal because they are often used with older breakout
boards that still require a "charge pump" signal.
