DIYbanter - View Single Post - woodworking machinery 60hz to 50hz operation.

On 23 May 2006 02:19:30 -0700, wrote:

hi all..
iam stuck in a gruesome situation..have placed orders for some heavy
duty wood working machinery from US.Most of these involve 3ph,220v,60hz
motors but i need to operate them at 220v,3ph,50hz supply.

It'll be fine. They _will_ work. They _will_ run slower.

-- Unless they're actually US made, where some of the makers have been
known to under-size laminations so that they only achieved their full
rated power when run on 60Hz. At frequencies below this the lower
frequency was less magnetically efficient and caused higher losses.
Fortunately the days America doesn't make anything any more and your
motors are probably Chinese -- the Chinese appreciate world markets and
design motors appropriately.

60 Hz motors all work at 50Hz. As the limit on motor power is basically
the acceptable temperature rise when under full load, the only effect of
moving from 60Hz to 50Hz on _any_ motor is at worst a reduced maximum
output power available. It's rare that you run motors in this region and
it's more likely that a high ambient temperature and poor colling would
be causing you more trouble anyway.

A frequency converting inverter will cost far more than a new motor and
is only sensible if you also need the variable speed feature. It's also
quite liekly to make the motors run _hotter_. If the inverter's output
isn't a smooth sine wave (and quality output costs real money) then the
extra high frequency harmonics in the output will cause more excess
heating than the frequency drop ever did.