I'm designing a system to inject an AC current into an AC bus. I'm trying to
get my head around something. To get current injected INTO the bus, would
the current have to be in phase or 180degrees out of phase with the voltage?
At first thought it would be to have it in phase but if you think about
this: Take an AC voltage and apply to a resistor. The current is in phase
with the voltage and current flows from voltage to resistor so it would make
sense that to inject current 180degrees out of phase, the current will go
into the bus. Is this correct?
Can you explain a little further on what you mean by "inject an AC current
into an AC bus"?
What are you trying to accomplish?
The more current and voltage are "out of phase" the worse your power factor
Way back at the dawn of the computer age there was a FORTRAN IV based
program called ECAP. This "modeled' an electronic circuit by breaking down
all electronic components into inductive and capacitive reactance's plus
resistance. It also provided for current and voltage sources.
If you use this or one of its more modern cousins you can plug in different
values and have it calculate the results.
If you try a "lab" experiment with real AC power you are likely to hurt
someone real bad.
I'd recommend your attention to
for a start in AC theory.
Yes, a load will draw a current from the bus- and this current will depend
on the load and the bus voltage. You don't "inject" a current. If the load
changes then its current will change.
Whatever current that loads draw from the bus is determined by the
loads -all the sources do is
If you are wanting to connect another source to the bus then, as suggested
by Palindrome, look at parallel operation of generators and load sharing
between generators. A bit more circuit theory might also help before you try
to "design" something.
In connecting the incoming generator it is necessary to match the <voltage>
magnitude and phase to that of the bus. If done correctly, there is no
current. If the voltage magnitude of the incoming generator is increased,
the main effect will be a shifting of reactive from the other sources on the
bus (not affecting the load except for secondary effects) not always what
you want. If you try to speed up the machine you will advance the phase of
the voltage (by a small amount, please) and some of the total power will be
provided by this machine- again without changing the load current or power.
Either way will result in a current from the incoming machine. It is better
to think of complex power flows than currents.
Don Kelly firstname.lastname@example.org
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