DIGITAL PHASE CONVERTERS AND 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.

FOR TECHNICAL ASSISTANCE CALL
605-343-7934 (8am-5pm MST).
Our knowledgeable staff of engineers and technicians are available to answer your questions.
EMAIL: INFO@PHASEPERFECT.COM

 

Other Products from PHASE TECHNOLOGIES

Pump Converters	Power Conditioners
Grid-Tie Wind Converters	Transformers