I have a milling machine that's starting to show its age. It has a 5 Hp,
208V, 3 Ph spindle motor that's currently on a full voltage Fwd/Rev starter.
Motor really slams when turned on and has damaged the variable speed sheaves
and keyways.

Was thinking of adding a soft start system in series with the original
starter. Considered a VFD but have heard that using one with a motor not
designed for such makes problems. Even adding a line reactor to remove
harmonic content may be required. All told, a soft starter appears to be the
best choice.

Does anybody have a favorite unit to recommend?
Ones I've seen so far have a SCR in series with two of the three legs and
control starting voltage and ramp-up time. If you keep them powered, they
can also control ramp-down time. A contactor bypasses the reduced voltage
system after the ramp time. All fine and well but only some of the vendors
seem to rate # of starts per hour. I would assume that this is due to heat
generation when the SCRs are carrying the load and the need to dissipate it.

Thanks in advance for any answers
Oppie