[RE-wrenches] Power Factor
Matt Tritt
solarone at charter.net
Sat Aug 1 15:28:04 PDT 2009
I took boB's advice and talked to Magnum about the problem. Their take
on it? "Hmmm, beats me!" I might be paraphrasing, but that's the drift.
All in all, I'd say that the suggestions from the group are at least as
good as the one's from the manufacturer.
Matt T
Larry Crutcher, Starlight Solar wrote:
> Don't forget, this is a Magnum inverter and Magnum has issues. I have
> two customers with Magnum problems. One is a washer that will work
> perfectly on a cheap import inverter; the other has a Vizio TV that
> works fine on shore power and generator. Soooo...maybe there are
> pumps and other items that are anti-Magnum.
>
>
> Larry Crutcher
> Starlight Solar
> (928) 941-1660
> Renewable Energy Products, Service and Installation
>
>
> On Aug 1, 2009, at 12:24 PM, boB Gudgel wrote:
>
>> Chris Worcester wrote:
>>
>>> Has he checked the torque on all the battery connections?
>>>
>>> Sincerely,
>>>
>>> Chris Worcester
>>> Solar Wind Works
>>> NABCEP Certified PV Installer
>>> Phone: 530-582-4503
>>> Fax: 530-582-4603
>>> www.solarwindworks.com
>>> chris at solarwindworks.com
>>> "Proven Energy Solutions"
>>>
>>>
>>
>> Also, Evidence of a bad battery connection (or bad inverter) should
>> be obvious if the house lights dim
>> when the pump tries to start.
>>
>> boB
>>
>>
>>
>>
>>
>>
>>
>>> -----Original Message-----
>>> From: re-wrenches-bounces at lists.re-wrenches.org
>>> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Matt
>>> Sent: Thursday, July 30, 2009 3:25 PM
>>> To: RE-wrenches
>>> Subject: Re: [RE-wrenches] Power Factor
>>>
>>> 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.
>>>
>>> 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 <boB at 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:solareagle at solareagle.com>
>>>>>>>>> *To:* RE-wrenches <mailto:re-wrenches at 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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