Those capacitors aren't for phase shifting to make a pseudophase, they
are for power factor correction to improve the voltage regulation. Phase
shifting with capacitors is very load dependent and users won't accept
that variation in phase angle. Sometimes in rural systems they use two
transformers open delta secondary, with just two phases of Y primary to
give a three phase. Often the utilization voltage is grounded at the mid
of one side so the three phase legs are 120, 120, and 187 volts from
ground (the wild leg). This runs three phase motors fairly well though
the unbalanced impedance shows up as unbalanced motor line currents that
if the motor is loaded fully can fry it.
What you call "primary," the power company considers to be the lowest
"distribution" voltage and while the final customers and their
distribution lines are often single phase, the substation feeding them
is always three phase and loads are as balanced as possible.
73, Jerry, K0CQ
--
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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