I suppose the winding in the various motors take a blown Transistor
or Triac without blowing up. That is good. Likely the reason why the
VFD blows - cheaper to replace and ok in anger impulse.

Martin

On 6/27/2016 3:09 AM, Gunner Asch wrote:
On Sun, 26 Jun 2016 22:14:50 -0500, Martin Eastburn
wrote:

So the 10hp motor might not turn over as fast anymore and caused
excessive current to flow, blowing up the VFD. Dirty bearings maybe
just got enough. The load was applied when it was designed to be
off and turned on once the motor was up to speed...

Was the motor shorted ? is there a shorted winding and just sat there
in a stall current to long ?

Think of the SYSTEM LLoyd - not just the source. You might buy 2 or 3
VFD's yet.

Now if the VFD is turned on with the motor disconnected, there might be
another issue. And so forth.


Martin

VFD design has some strengths and some weaknesses. Many/most VFDs
have a couple of BIG capacitors in them...and they blow up and take
out the main power transistors. In fact..I have a decent sized box
with about 8 blown VFDs that came out of machines that were running
perfectly and then one day..they didnt work anymore. Generally inrush
current takes out the caps and then the trannys.

Mitsubishi was the worst in my experience..one could get about 10 yrs
out of them..then Poof.

My mill had one attached to it for a decade (PC3) ..and one day..it
quit. Caps went bad. Ive not gotten around to replacing them as of
yet.

ALL of the CNC machines that I fix use a VFD to run speed control,
along with a gearbox. When a cnc quites spinning the spindle..its
almost Always the VFD gone bad.

Gunner


On 6/26/2016 6:40 AM, Lloyd E. Sponenburgh wrote:
Martin Eastburn fired this volley in
:

Try to understand why it blew - is it under strain due to dry shafts ?
Wrong lube or something causing more back pressure ... Might be
important to check first - less you buy another in due time.


It's 12 years old, used 8 hours a day, daily for 8years of that, and thrice
weekly for the last 4. "Dry Shafts"? "Back pressure"? "Wrong Lube"? This
is a VFD. A 10HP spindle driver.

It blew up upon application of power, not while cutting.

LLoyd


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