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Phase Perfect® Digital Phase Converters & Rotary
Phase Converters
Phase
Perfect digital phase converters are a new concept in phase
converters, offering a better performing alternative to
typical rotary phase converters.
It is helpful to understand
how a rotary phase converter works when comparing one to a
Phase Perfect digital phase converter. Phase Perfect is
similar to static and rotary phase converters in that two of
the phase leads to the load come directly from the power
line, and the third lead is generated by the converter. At
that point the similarity ends.
A rotary phase converter is
a slightly modified three-phase motor used in conjunction
with capacitors. After start capacitors kick-start the
motor, it will run with two of the motor windings powered
from L1 and L2 of the single-phase service. The third
winding, sitting in the rotating magnetic field inside the
motor, generates the third leg (call it L3), phase shifted
from L1 and L2. If L3 is generated at the proper phase angle
and voltage, all the phase-to-phase voltages (L1-L2, L2-L3,
L3-L1) will be equal, or “balanced”.
Voltage balance is important
for safe and efficient operation of three-phase motors and
other three-phase systems. Unbalanced three-phase power has
the potential to damage equipment and requires that motors
be de-rated.
The challenge for any phase
converter is to generate L3 so that the phase-to-phase
voltages are balanced. With a rotary converter, the
manufacturer adjusts the L3 voltage by connecting a motor
run capacitor between one of the single-phase input lines
the third winding of the motor. By adjusting the capacitor
value, the voltages can be balanced fairly close. Voltage
unbalance can occur when the current (amperage) demanded by
the load changes. Even though the L3 voltage may have been
adjusted at the factory, load changes will cause this
voltage to fluctuate, creating voltage unbalance. The
voltage from L1 and L2 is much more stable because it is
supplied by the utility.
So while some rotary phase
converters claim to be balanced, this can be so only at one
amperage level. The end user likely has no idea what that
amperage might be. Many three-phase loads are highly
variable and/or highly susceptible to damage from voltage
unbalance. A rotary phase converter has no voltage
monitoring circuits to know when it is out of balance, and
even if it did, it has no way to adjust the L3 voltage to
maintain voltage balance.
In contrast, a Phase Perfect
digital phase converter generates the L3 voltage with
double-conversion power electronics technology. It does not
utilize a motor and in fact has no moving parts aside from
small cooling fans. Voltage monitoring circuits and
software in a digital signal processor control the voltage
generating process, ensuring the L3 voltage is generated to
always maintain voltage balance within 1%. Variable loads
and voltage sensitive equipment can be safely operated on
Phase Perfect digital phase converters. Ideal applications
for Phase Perfect include CNC machines, submersible pumps,
elevators and all types of fully loaded motors.
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PHASE CONVERTERS
DPC-A10 Data
Sheet
DPC-20 Data
Sheet
DPC-30 Data
Sheet
Phase Perfect digital phase converters
are UL listed in the USA and Canada. |
