Legacy P&O Tracking Issue Upon Exiting Manual EQ

[Vic]

Have seen this a number of times previously.

Today did a Manual EQ.  The Classic was in Legacy P&O.

During the EQ,  this single Classic was delivering about 62 A at 64.5 V TempCompensaged --  about 4kW.

The Classic exited EQ on its own  --  1:20:00  time had elapsed.   Manually Reset Net Ah to zero from 71.

Came back to the residence,  from the Power Room.   Composed another Post,   restarted the LA,   and noticed that the Classic was in EQ (seemingly on its own),   the Vin to the Classic was 119V,  about 860 watts of power was being produced.

Tried to Force Float in the LA (probably should have Stopped the EQ in the LA).   Was unable to initiate the Float stage.   Went back to the Power Room,   and tried to lower the Voc with the left soft button,   which did work.   Lowered the Voc to about 102 V,   and of course,   the Classic made lots more power.   Pushed Enter (still in P&O),   and that initiated a new Sweep,   and the Classic found a good Voc of about 100 V.

At some point in the above,   Manually Stopped EQ,   which seemed to work this time.

Have seen,   many times in the past,   that after an EQ in P&O Mode,   that the Classic can get hung up in a Sweep at very high Voc,   producing 10 - 20% of the available power at that moment from the PVs.

Have also seen this behavior,  when switching from Solar Mode,  to P&O during an EQ  --  seems to be something about EQ,   that the Classic's P&O Sweep does not like (?).

Classic S/N 3677,  Cl FW 2126 .

Anyway,   FWIW,   Vic

Do not know how the Classic got back into an EQ.

[boB]

What is the EQ time set to naturally stop at ?

BTW, you mean MPPV rather than Voc I think.

I don't think that Legacy P&O has anything to do with this but ?...

So, let me undertand.  The EQ stopped and did not return after you hit Manual EQ STOP ?

Or it did return to EQ after that ?

[Vic]

Hi boB,

The 1:20:00 was the EQ Time setting  --  one hour and twenty minutes.   Did watch the EQ time count down,  since there were only 4 minutes remaining on the EQ countdown timer upon getting to the Power Room.  It timed out,   and exited EQ on its own (I think - saw the WB current go negative from its nominal ending WB current of 54.5A,   and the EQ time setting had  been satisfied).

The 119 V was not actual Voc,  but was in a hurry to get back to work,   and what I meant was this is the input voltage to the Classic,   with PVs loaded only to about 20% of what would have been the power available from PV at that time (about 4,000 watts available) were the PVs not so lightly-loaded by the Classic.   Not really Voc,   but not the string Vmp that would be expected at that time during the EQ.  MPPV is not a term that I am familiar with,   the 119 V was not string Vmp expected at that time (about 100V),   and not really Voc  (the power output went from 860-ish watts with Vin of 119 V to over 4,000 W  after we got the Classic to re-Sweep).   The STC String Vmp is 106 V,   at 25C cell temperatures.

Do not know what happened after the Classic ended EQ by timing out on its own.   Was walking back to the residence,   and did not look at the LA until about 30 minutes after the Classic ended the Manual EQ on its own,  after spending one hour and twenty minutes EQing,  with no interruptions due to loads on poor PV  production.

Went back to the Power Room,   and used the MNGP to Stop the second EQ,  which worked.   The second EQ seemed to start on its own,   but I was able to stop it manually on the MNGP.

Thanks,    Vic

[boB]

OK... 

MPPV = Vmp

I should learn to use Vmp instead of MPPV  !

[Vic]

OK... 

MPPV = Vmp

I should learn to use Vmp instead of MPPV  !

MPPV  did seem to be Vmp,    BUT,   since  the PVs were SO lightly-loaded,  it was not close to String Vmp,   and of course, the Classic was in EQ-MPPT,  BUT  that input voltage to the Classic was far above the String Vmp for the PV Cell  temperature and Irradiance conditions at that moment (MPPV for that moment was about 100V) SO,   that was why  the MPPV term was causing some uncertainty.

Believe me,  I am not a person who would try to "correct"  anything that you might say   ...   was just trying to be a bit more clear of what was seen here ...

All   FWIW,   THANKS,   Vic

[Vic]

Will add that today,   the day following this curious Tracking thing,   still in P&O,  that the Last Voc shows as 100.2 V.   With the Classic delivering about 2400 watts (mostly to an electric heater),   that the Vin to the Classic reads 112 V,  with the PVs loaded about 60-ish percent.

Loading the Classic beyond the power capability of the PVs does not seem to change this Last Voc shown on the LA.

This Last Voc was probably from hours ago,  perhaps the first full Sweep of the day (?).   This probably has nothing to do with the event reported yesterday.

FWIW,  Thanks,  73,  Vic  --     kilo six italy charlie.   

[boB]

Yes, in Legacy sweep mode, the last Voc could have been from a long time ago.

If you get up REALLY early and watch, you should notice that the Classic will turn on and off several times before it stays on.

Got to get above that 20 or so watt minimum power level before it stops cycling.  The logs can sort-of show this if it's trying over a 1/2 hour or so.

You are in California I think so it probably takes less time to wake up than it does here.  Least amount of time I would expect at the equator.

boB
K7IQ

[Vic]

Yes, in Legacy sweep mode, the last Voc could have been from a long time ago.

If you get up REALLY early and watch, you should notice that the Classic will turn on and off several times before it stays on.

Got to get above that 20 or so watt minimum power level before it stops cycling.  The logs can sort-of show this if it's trying over a 1/2 hour or so.

You are in California I think so it probably takes less time to wake up than it does here.  Least amount of time I would expect at the equator.

boB
K7IQ

Hi boB,

YES,  most mornings,   we DO watch the Classic wake-up a number of times,   make a bit of power,   but too little to made it worthwhile to run the Converter,  and again Rest.   We do also hear this behavior while on 3777 kHz  --  the Classic has a birdie on 3777.4-ish kHz (zero beat frequency).  We are in a rag-chew group on 3777.   Believe that Classic power below about 15 Watts is about the no-go  limit.

None of the apparent behavior on the P&O Mode is too problematic.   If nothing else,  the Classic would get a GOOD Voc on the following morning  --  assume that this P&O situation could well  be an issue with Auto EQ,  as well.

But,   had been think about some of the new CCs which could well use the Tracking routines from the Classic,   and that perhaps,   possibly come up again with those CCs,   ...   perhaps.   Had guessed that if P&O Mode re-Swept on occasion,   that the Classic might well get itself out of being stuck at 10  or 20& of the available PV  power.   Not to try to guess just how the P&O logic is performed,   or to try to tell you what you should do,   ...    and  so  on.

73  Thanks,    Vic in Central CA.

[boB]

Too bad you can't just tweak the switching frequency slightly to get rid of the 3777.4 ish beat.  Just slightly, maybe up about 2 or 3 kHz !

The Classic is at around 25 kHz per cylinder (there's two buck converters, interleaved 50%) but can create 50 kHz spaced EMI.

It is more efficient where it is sitting, frequency wise but it isn't 100% tweaked in efficiency so could probably change 1 kHz one
way or the other...

Hmmmmm...

So, when is your net on 3777 ?  I should listen.  I am 75 meter capable more in the car mobile because the noise in my neighborhood has gotten pretty bad in the last few years.  I should try listening anyway.

[Vic]

Hi boB,

The birdies need to be somewhere.  It is really notta problem.   Sometimes in full sun,  and drop by that frequency  the sidebands on that "carrier"  make quite  a racket.  Before the advent of the LA,  one could kinna tell what charge stage the Classic was in,   and even if it is in Current Limiting by the sound of the LSB (in this case).  With little power being produced,  that carrier is quite clean and stable (probably derived from some XTAL oscillator.

Had noticed,  that fairly often the signal strength of alternate birdies would be slightly different,   and had thought of it as a Bi-phase converter of some king.   More recently had read that you called it a "two cylinder"  converter,  which has a nice ring to it,   and is quite descriptive for an engine producing power !

We used to have Common-Mode chokes on the battery cables from this CLassic,  to the battery,  but removed it because it added a bit of voltage drop.  Any real drop at all caused Opportunity Loads to change battery charge current due to this drop,   and this drop really upsets the needed value of EA,  so we ditched the filter (which was fairly effective in attenuating this noise).   Even the Airpax E Frame breaker drops about 1  mV/Amp of Classic output current (measured right at the breaker terminals)  this also has a negative effect of the operation of EA.

Have a large Differential-Mode AC Line filter that will try next,  as drops in that circuit have much less effect,  of course.

Our 75  M group is a loose-knit group of mostly retired folks.  We begin between about 6:30 AM,  which is getting less common,   and about7:30 - 8:00 AM,  most days.   There are often some hanging out intermittently throughout the day. Of course,   as the Sun gets higher in the sky,  Absorption affects more distant comms,   so we sometimes go to 60 Meters.

73,  Thank you very much for working,  essentially 24/7/355.   We all really appreciate it.   As was noted in another Post,   there is absolutely NO other company that makes its Principals and Engineers/Engineering Leaders available,  at all EVER,  let alone,  after hours !!  [just try to get ahold of Schneider Electric Engineering!]

Thanks ! 73  Vic

[boB]

Thanks for the kind words, Vic.

OK, so sounds like you are up a bit too early for me, unless maybe I am driving to work.  I have kinda been more on 40 meters lately cuz I have to change the ham-stick but that isn't such a big deal.  I also have an MFC antenna tuner in the trunk right at the base of the trunk lid mount.

So, I may have an idea on your common mode choke messing with things...   That choke, to be common mode should probably be around all 3 wires going into the Classic.. That is unless you have a separate PV negative and separate battery negative.  IF only 3 wires are used, then there will be a difference current riding on that common negative going into the Classic terminal block.  Difference between PV input current and battery output current as I remember.  It's kind of weird.  MAYBE that is it ?  Or not.

boB

[Vic]

Hi boB,   been a bit busy,   sorry for the reply delay.

When doing Common Mode (CM) chokes,  have treated the PC cables ad one circuit,  and the Classic battery cables as a separate circuit.

On this particular system,  the CC's CM choke on the cables to the battery have been removed to try to reduce the voltage drop represented by the five of so feet of #6 AWG cable that is the choke windings.   Had thought that the PV cables would,  by far be the greatest contributor to Emission radiation,   but have not done experiments to see where the emissions originate.

The power rooms are each Cargo containers,  which are fairly RF  tight,   PV cables are in EMT conduit,   the AC outputs from the inverters in metal conduit above ground,   and buried in PVC conduit 30" underground.

The wiring in the cabin is all in Coleman Corraclad  (r)  (is that it?),  which is THHN cables inside a continuous AL corrugated (not wound) sheath. All in an un-scientific attempt to reduce EMI/RFI emissions.

All of the Classics here use one negative for the PVs and another for the battery negative from the CC.  The other main power system has two Classics,  and a fairly large CM choke in the battery cables for each CC,  as well as a separate CM choke for the PV cables for each Classic ...   FWIW.

Had not thought of using a single CM choke for both PV and battery cables,  though.

Thanks boB for your time.   73,  Vic