Re: [CAD_CAM_EDM_DRO] Re: VFD's / Skates

In a message dated 10/2/01 12:44:48 PM Hawaiian Standard Time,
johnhe@... writes:

<< Why is it the VFD is the
way to go? >>
John,

Soft start. No lights dimming or computers, CNC or otherwise crashing due
to brownouts. No output derating as with static converters. No constant
running rotary phase converters. Instant speed change. Lower tooling cost
since tools can be run closer to ideal speed. Orderly stop and acceleration
in opposite direction if commanded. Fantastic tapping control with instant
starts and stops. No wasted time waiting for spindle to coast to stop. No
dealing with high maint mechanical speed controls. Ability to run with single
or three phase power. Ability to run odd voltage moters on standard power -
for instance 380 volt motors on 440 lines - 200 volt motors on 240. Ability
to program motor overload current in small increments to prevent tool or
drive train failure. Ease in interfacing to 0-10 volts CNC speed control
outputs or PLCs.

These are a few reasons that I can think of now, There are many other
reasons why they are so neat. There are a few down side issues but they are
easy to manage. Over speeding and insulation stress are two that come to
mind.

Peter
THRD, Inc.