Matt wrote:
Possibly a PF question, or maybe one for Magnum - boB,
One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna AE
48. Or rather, he isn't. According to him when he first fired it up, it
operated the pump just fine. The next time he tried, though. he couldn't even
get a buzz out of the starter. No workee.
Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?
If there is enough ac voltage applied to the pump, the it should do
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ? Otherwise, I
would suspect it might be a surge problem.
Is there a pilot light or something ? Maybe a fuse blew or breaker
tripped somewhere ? (when the pump went off?)
Doesn't sound like a PF problem though... However, since you mention
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.
The Magnum does that just fine, as does any other
decent inverter.
Maybe Tony, Eldon or Gary at Magnum has seen this before ? 425-353-8833
boB
The inverter runs all the other loads in the house fine, just not the pump. He
can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a motor
starter problem or an inverter issue? I have to admit to being somewhat baffled
by this one because it ran the pump once, but not after.
Matt T
---- boB Gudgel <b...@midnitesolar.com> wrote:
boB Gudgel wrote:
>>So, because of the different ways of specifying PF, it is always best
to think of Power Factor as being the ratio of real (in phase) power, or
VA to reactive power >>(VARS or "Volt Ampere Reactive"). That will
work in all cases.
OOOps ! See, this can get confusing. Reverse what I just said Power
Factor... " Definition: The ratio of true power to apparent power" as
David Brearley had just posted. Otherwise, that calculation can give
you an answer that is GREATER than 1.0 and you don't want that !
Had to eat some of my words. I just wanted to point out that the phase
shift method was called DPF. Didn't Ian Woodenden do an article on PF
recently too ? If not, he or someone probably should in one of the two
HP magazines.
boB
R. Walters wrote:
Power factor expresses the time difference between voltage peak and
current peak on each of their sine waves. If both current and voltage
waves are "in time", (their wave peaks match up) power factor is 1.
If one is ahead or behind the other, it's not. Think about an
electric motor: we hit it with a voltage wave, and a fraction of a
second later, it actually moves, and the current wave happens. There
is a little lag there. Resistive loads like lights have very little
lag, and big electric motors coming up to speed can have horrible PF.
This definition of power factor only applies for linear loads with
only inductance or capacitance (with resistance) and is called
"Displacement Power Factor (DPF) and you will see that on some power
meters.
For non-linear loads, like battery chargers or computer power supplies
without PF Correction, the current waveform (on an O-scope) looks
nothing like a sine or cosine wave. The current "spikes up" at the
AC voltage peaks. It actually *looks like* it might be in phase, BUT
the current and the voltage do NOT look the same. It's non-linear.
Lower than 1.0 power factor for sure.
For a grid tie inverter, resistive heater or any load that has a PF of
1.0, the current and voltage waveform will both look exactly the same
AND there will be no phase shift. They are both linear and all
current and voltage is in phase at every point in the AC cycle.
So, because of the different ways of specifying PF, it is always best
to think of Power Factor as being the ratio of real (in phase) power,
or VA to reactive power (VARS or "Volt Ampere Reactive"). That will
work in all cases. (Real Vs. Apparent power is the same thing).
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt
Amperes) V x A will be the highest measured number, that is unless
the PF = 1.0 in which
case both will measure the same.
Some of that measured VA, or apparent power will be "in phase" and is
the "real" or "true" power. Some of that VA may be reactive,
(inductive or capacitive that is) and is the "out of phase" portion.
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase
in current and voltage.... It's just a matter of how MUCH of your
power is 0 degrees phase shift and how MUCH of that VA is + or - 90
degrees out of phase. If ALL of the current is in phase with the
voltage, then
the power factor is 1.0. That is, if you lay them on top of each
other, they will look the same on an oscilloscope if power factor = 1.0
It can get way more complicated that this too, but that's basically
it. Feel free to add to this.
boB
power meters.
There is much more to it, with reactance, "real" and "imaginary"
numbers?!, etc. but basically, we wrenches need to know that
everybody wants Power factor to be close to 1.
Obviously there isn't PF on DC, and it is my understanding that most
inverters can operate at most power factors. Not 100% sure, but I
think GT inverters would help not hurt the PF problem in most
situations.
Correct me on any and all of this, Oh fellow wrenches,
R. Walters
Solarray.com
NABCEP # 04170442
On Jul 30, 2009, at 9:19 AM, boB Gudgel wrote:
Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it
to British Columbia Hydro? :-|
I think they must be misunderstanding what they are asking for but
the question is in the section for PV and on the same line as the
total output in Kwh of the PV. Power Factor %
It was most likely just a trick question.
You're gonna fool them, though ! :)
boB
I'll contact them and see where this goes but I don't fully
understand what power factor is which will make it hard to argue my
case. My understanding is that it is the difference between what
the utility supplies to a residence vs. the actual loads being used
by that residence expressed as a percentage. I came across the
following course offering by SEI that discusses Power Factor with
reference to PV:
POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS Presented By:
Michael Smith of Alpine Management Systems
This session will deal with power factor: What is power factor?
What causes low power factor? Why improve your power factor? This
session will explain the role of power factor correction as it
applies to solar installations. There are currently over 67,000
KVAR installations in 26 countries resulting in phenomenal energy
savings with a corresponding reduction in greenhouse gas emissions.
Session includes several KVAR installations and the resultant
savings.
http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf
Ron
On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:
There is no such thing as a power factor for DC or for panels.
..................................................................................................
Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..................................................................................................
----- Original Message -----
*From:* Ron Young <mailto:solarea...@solareagle.com>
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Sent:* Wednesday, July 29, 2009 5:45 PM
*Subject:* [RE-wrenches] Power Factor
Can anyone point me in the direction to find the power factor for
Sanyo HIT N 205 panels? The utility is requesting it on a net
metering interconnection application. Ron Young
earthRight Products - Solareagle.com
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