[rescue] Re: Us versus German power

Michael Thompson m_thompson at ids.net
Thu Jan 16 07:19:16 CST 2003

>>>>>> "James" == James Lockwood <james at foonly.com> writes:
>    James> On Wed, 15 Jan 2003, Jochen Kunz wrote:
>    >> Is three phase power really that uncommon in the USA??? In good
>    >> old Germany we have 230 V @ 16 A three phase ...
>    James> For businesses, especially in industrial areas, it's
>    James> reasonably easy to get. ...
>    James> Usual residential power distribution in the USA is
>    James> center-tapped 240V 1ph. ...
>    James> Usual 3-phase distribution is either 120V/208V Wye (120V from
>    James> each phase to neutral, 208V phase to phase) or 240V delta
>    James> (240V phase to phase).  ...

A lot of equipment uses the power distribution in a different way than it
was intended. The load on a Wye source is usually between the neutral and
the phase. Some computer equipment that is fed by a Wye source has the
power supplies connected on the 208V phase-to-phase and has the convience
outlets on the 120V phase-to-neutral. This equipment could be connected to
a Delta power source if the convience outlets were not needed.

I just converted a DEC RP06 disk drive from 120V/208V WYE to single phase
220V. This drive has a plug on the power controller so it can be powered
from just about any 3-phase source. The spindle motor is single phase and
was connected between two of the three phases. The electronics power supply
was connected between two more phases. The Massbus electronics has a 220V
transformer connected to the third pair of phases that generates a pair of
120V and a neutral for the fans. I just connected everything up to the
single 220V phase and it works fine.

Michael Thompson
E-Mail: M_Thompson at IDS.net

More information about the rescue mailing list