[ Ray Finch wrote in 060117 MMDigest:

> Realistically, to cause any damage to a player piano motor, it would
> have to be exposed to an over voltage long enough for the motor to
> overheat.  Depending of the size and length in time of the over-voltage,
> damage from overheating could take anywhere from 3 or 4 minutes to over
> a half an hour.  The short power glitches that you are likely to see
> from modern electric power are usually in the millisecond range -- far
> too fast to get anything in a player piano to burn up.

That is certainly true in the case of newer motors, but we're dealing
here with antique motors, some of which are old enough that their
insulation isn't what it used to be.  A short spike can permanently
break down the insulation, either between two windings or (worse)
between the windings and laminated motor core.  This in turn will
provide a path for short-circuit current, causing the motor to
overheat.

I believe that player piano motors were made in weird shapes, and it's
profitable to keep them happy as long as you can; rewinding is terribly
expensive.  Therefore, both surge protection and fuses are important.

Mark Kinsler