Re: [NSW] 3 phase AC propulsion system (was: Millennium Train sets)

[Rob Kearey <robk@powerup.com.au>]

Andrew Price wrote:

> On Sun, 02 Apr 2000 10:18:39 +1000, David Johnson
> <trainman@ozemail.com.au> wrote:

> >Chris Downs wrote:

> >> I've found the acceleration/deceleration whine on the IMUs and SMUs to be
> >> more noticeable than on G7.

> >Are you sure that isn't the Oil cooling fan you can hear?

> AC traction packages vary the voltage and frequency to control the
> power output of the drive motors and this is *very* audible.  There is
> no mistaking a three-phase drive with either a DC drive or its
> ancillaries.

You've missed the point, I'm afraid. On IMU and SMU Mk 1 sets, the most
prominent noise is that of the oil cooler/impeller for the traction
transformer. The AC motors are very quite indeed.

On SMU Mk II sets, the AC motors make a much louder "whine", which steps
up and down as well as rises and falls. It's very distinctive indeed.

Rob K