P
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. cicuit need to fire control solenoids for hydraulic controls. The motor is a half-horse 120v 60 cycle that drives a hydraulic pump. Onaverage - 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 Killawattwhile 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
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. Onaverage - 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 Killawattwhile 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