On Wed, 02 Sep 2009 17:33:23 +0100, John Rumm wrote:

Harry Bloomfield wrote:
on 02/09/2009, Bob Mannix supposed :
When it's buzzing, give the motor a tweak by hand. If it then runs,
it's an induction motor and the starting capacitor has blown. If it
doesn't, the brushes may have stuck or something.

They are not, so far as I know, a capacitor start motor, nor have they
any brushes - just a straight DOL induction motor.

I am sure its an induction motor, but I would be very surprised if it
did not have a start cap.

I have one similar if not the same. Try taking the drive belt off and
see if the motor runs without the belt. Is the buzzing definitely coming
from the motor, rather than the NVR's coil? If from the NVR, it could be
that some dirt or etc. is preventing it closing fully.

I seem to remember there is an interlock on the belt drive cover, to
prevent it running with the belt exposed.

Yup, I think this is an elf'n'safety requirement.

That'll be the EC Machineries Directive probably.

When I used to work for a large compressor manufacturer, the relevant
directives said that all removeable covers should be interlocked - our
compressors had dozens of bolted covers and were only used in fixed
situations where trained maintenance staff and permits to work etc. were
required (oil rigs, refineries and the like). We pointed out to Brussels
that the compressor specific directive was not really applicable to our
equipment, as it was written around portable units and finally received a
letter officially stating that our 100 ton compressors with 8 MW motors
"were not machines" !!!

SteveW