A UPS is rated to normally operate on 208V, but can be configured to operate
also on 200V, 220V, 230V, and 240V. It comes with NEMA 6-30P plug and has
NEMA 6-20R x2 and NEMA 6-30R x2 outlets. These are standard for USA 208/240
volt circuits that have no neutral connection.
What system type would you expect such a UPS to output when it is configured
for each of the voltages (200, 208, 220, 230, 240)? Would you expect each
hot wire, when measured relative to ground (not neutral since there is no
neutral) to be 50% of the L-L voltage and a phase angle of 180 degrees, or
57.7% of the L-L voltage and a phase angle of 120 degrees? Would you expect
the phase angle (and hence L-L : L-G ratio) to be different with different
voltage settings?
If it ONLY had voltage choices of 208 and 240 I could believe it might do
this by keeping the L-G voltage at 120 and varying the phase angle. But
with the other voltages being an option, I'm not so sure. While any of
those voltage could be derived from selected phase angles of 120 volts, I
would expect that to actually be an odd thing to do.
I'm curious if such a unit could be run on 208V input (two phases in a
208Y/120 system) and 240V output reasonably (it can apparently be set to
do that so I would think the vetted the design for it). I'm just not sure
what kind of system I'd be getting (120/240 at 180 degrees or 139/240 at
120 degrees). Given that it has no neutral, clearly they are not expecting
any L-N loads. But some devices could, in theory, monitor a L-G voltage
and treat 139 volts as overvoltage.
I am currently looking at the APC model SURT5000RMXLT.
also on 200V, 220V, 230V, and 240V. It comes with NEMA 6-30P plug and has
NEMA 6-20R x2 and NEMA 6-30R x2 outlets. These are standard for USA 208/240
volt circuits that have no neutral connection.
What system type would you expect such a UPS to output when it is configured
for each of the voltages (200, 208, 220, 230, 240)? Would you expect each
hot wire, when measured relative to ground (not neutral since there is no
neutral) to be 50% of the L-L voltage and a phase angle of 180 degrees, or
57.7% of the L-L voltage and a phase angle of 120 degrees? Would you expect
the phase angle (and hence L-L : L-G ratio) to be different with different
voltage settings?
If it ONLY had voltage choices of 208 and 240 I could believe it might do
this by keeping the L-G voltage at 120 and varying the phase angle. But
with the other voltages being an option, I'm not so sure. While any of
those voltage could be derived from selected phase angles of 120 volts, I
would expect that to actually be an odd thing to do.
I'm curious if such a unit could be run on 208V input (two phases in a
208Y/120 system) and 240V output reasonably (it can apparently be set to
do that so I would think the vetted the design for it). I'm just not sure
what kind of system I'd be getting (120/240 at 180 degrees or 139/240 at
120 degrees). Given that it has no neutral, clearly they are not expecting
any L-N loads. But some devices could, in theory, monitor a L-G voltage
and treat 139 volts as overvoltage.
I am currently looking at the APC model SURT5000RMXLT.