Posted by hubops on March 21, 2013, 10:34 pm
On Wed, 20 Mar 2013 20:57:05 -0700 (PDT), philkryder at gmail
> 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.
>Time has passed.
> I installed corrective capacitance based on my spreadsheed and formulas
>provided by others in the group. Thanks for all the help.
>More Time passed.
>What we learned recently is that though the AVERAGE powerfactor is "low" - .5
or less sometimes,
>there are SPECIAL PEAK LOAD EVENTS that may last for a few seconds (less than
5) every minute or two.
>Coincident with those peak load events, control circuits in the same
"neighborhood" -
> i.e. circuit 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...
>You can guess where this is going.
>When the load is applied voltage drops from 120 nominal to 106 or so. Solenoids
fail to fire.
>Power factor changes dramatically.
>So, given that my KillaWatt only does averages, we rented a Fluke meter that
records mins and maxes
> within each one-minute interval.
>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.
>Any other suggested actions?
>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"
>thanks in advance.
>Phil
It seems that we're talking about fairly small ac motors (?)
hence small-ish capacitors (?) which might have a significant
recovery time (?)
Are the solenoids trying to pick-up before the capacitors have
recharged ?
.. just a thought.
Is there any way to time-delay the solenoids ?
... even for a test .. ?
... dunno.
John T.
Posted by philkryder on March 22, 2013, 12:22 am
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.
>
>
>
>
>
> Time has passed.
>
>
>
> I installed corrective capacitance based on my spreadsheed and formulas p
rovided by others in the group. Thanks for all the help.
>
>
>
> More Time passed.
>
>
>
> What we learned recently is that though the AVERAGE powerfactor is "low"
- .5 or less sometimes,
>
> there are SPECIAL PEAK LOAD EVENTS that may last for a few seconds (less
than 5) every minute or two.
>
>
>
>
>
> Coincident with those peak load events, control circuits in the same "nei
ghborhood" - i.e. cicuit need to fire control solenoids for hydraulic contr
ols. 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 so
lenoid opens a valve to a hydralic motor and then, other solenoids open val
ves to hydraulic cylinders...
>
>
>
> You can guess where this is going.
>
>
>
>
>
> When the load is applied voltage drops from 120 nominal to 106 or so. Sol
enoids fail to fire. Power factor changes dramatically.
>
>
>
> So, given that my KillaWatt only does averages, we rented a Fluke meter t
hat records mins and maxes within each one-minute interval.
>
>
>
> I'm inclined to re-tune the capacitors based on highest power Factor see
n over an entire 10 hour shift, rather than the average seen by the Killawa
tt while I happen to be looking.
>
>
>
> Any other suggested actions?
>
>
>
> 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 causin
g the circuit to be "over corrected"
>
>
>
> thanks in advance.
>
> Phil
more background data.
we are off grid.
We're not trying to save money.
We're trying to run more reliably.
Our initial problem was popped breakers due to the high current flow due to
the imaginary current.
thus the power factor correction.
step 1 was to remove the caps. - done.
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?
Posted by j on March 22, 2013, 8:16 pm
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.
>>
>>
>>
>>
>>
>> Time has passed.
>>
>>
>>
>
>
>
>> I installed corrective capacitance based on my spreadsheed and formulas
provided by others in the group. Thanks for all the help.
>>
>>
>>
>> More Time passed.
>>
>>
>>
>> What we learned recently is that though the AVERAGE powerfactor is "low" - .5
or less sometimes,
>>
>> there are SPECIAL PEAK LOAD EVENTS that may last for a few seconds (less than
5) every minute or two.
>>
>>
>>
>>
>>
>> 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...
>>
>>
>>
>> You can guess where this is going.
>>
>>
>>
>>
>>
>> When the load is applied voltage drops from 120 nominal to 106 or so.
Solenoids fail to fire. Power factor changes dramatically.
>>
>>
>>
>> So, given that my KillaWatt only does averages, we rented a Fluke meter that
records mins and maxes within each one-minute interval.
>>
>>
>>
>> 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.
>>
>>
>>
>> Any other suggested actions?
>>
>>
>>
>> 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"
>>
>>
>>
>> thanks in advance.
>>
>> Phil
>
>
> more background data.
>
> we are off grid.
>
> We're not trying to save money.
> We're trying to run more reliably.
>
> Our initial problem was popped breakers due to the high current flow due to
the imaginary current.
>
> thus the power factor correction.
>
> step 1 was to remove the caps. - done.
>
> 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?
>
>
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?
Posted by Jim Wilkins on March 22, 2013, 8:45 pm
> On 3/21/2013 8:22 PM, philkryder@gmail.com wrote:
> 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?
Or an accumulator?
http://www.engineersedge.com/hydraulic/accumulator_equations.htm