From: mung_me@att.net   
      
   On 3/21/2013 8:22 PM, philkryder@gmail.com wrote:   
   > On Wednesday, March 20, 2013 8:57:05 PM UTC-7, philkryder at gmail wrote:   
   >> A couple years back some folks in this group helped me to use a KillaWatt    
   device to deterimine powerfactor on some "lighly loaded" ac motors.   
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   >> Time has passed.   
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   >> I installed corrective capacitance based on my spreadsheed and formulas   
   provided by others in the group. Thanks for all the help.   
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   >> More Time passed.   
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   >> What we learned recently is that though the AVERAGE powerfactor is "low" -   
   .5 or less sometimes,   
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   >> there are SPECIAL PEAK LOAD EVENTS that may last for a few seconds (less   
   than 5) every minute or two.   
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   >> Coincident with those peak load events, control circuits in the same   
   "neighborhood" - i.e. cicuit need to fire control solenoids for hydraulic   
   controls. The motor is a half-horse 120v 60 cycle that drives a hydraulic   
   pump. On average - 95% of the time    
   - there is no load - but, when there is a a solenoid opens a valve to a   
   hydralic motor and then, other solenoids open valves to hydraulic cylinders...   
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   >> You can guess where this is going.   
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   >> When the load is applied voltage drops from 120 nominal to 106 or so.   
   Solenoids fail to fire. Power factor changes dramatically.   
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   >> So, given that my KillaWatt only does averages, we rented a Fluke meter   
   that records mins and maxes within each one-minute interval.   
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   >> I'm inclined to re-tune the capacitors based on highest power Factor  seen   
   over an entire 10 hour shift, rather than the average seen by the Killawatt   
   while I happen to be looking.   
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   >> Any other suggested actions?   
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   >> Also, "what happens" with a corrected circuit at a 98% power factor when   
   the load increases and the motor's power factor rises from .5 to .85 causing   
   the circuit to be "over corrected"   
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   >> thanks in advance.   
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   >> Phil   
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   > more background data.   
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   > we are off grid.   
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   > We're not trying to save money.   
   > We're trying to run more reliably.   
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   > Our initial problem was popped breakers due to the high current flow due to   
   the imaginary current.   
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   > thus the power factor correction.   
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   > step 1 was to remove the caps. - done.   
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   > I still have the question "what happens when the caps are in place and the   
   motor's power factor improves to .85 from the average .5?   
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   That power factor was inductive before. What you don't know for sure is   
   whether with the caps and the loaded motor whether it had become   
   capacitive. I think it may have, particularly if you had compensated to   
   a PF of 1.   
      
   You have a complex system,if you were on grid the grid would absorb the   
   resulting voltage spike. But your inverter has to deal with that and   
   what it does is unknown. Have you considered a DC pump?   
      
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