[RE-wrenches] Power Factor
Larry Crutcher, Starlight Solar
larry at starlightsolar.com
Sat Aug 1 12:08:54 PDT 2009
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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