The PF of such a small load is of no consequence compared to the power used in a building. A capacitive power factor is actually an advantage since it cancels some of the typical inductive (lagging) PF that is common in the mains supply.I've been testing cheap led bulb to decide whether to use a few in a building that has pf problem already.
Only a few, so it's not a big deal. Just on principle, I want to be going the right direction.
Even though they are bad. .55 pf it appears to be capacitive.
The led tubes I've been using are over .90.
Does it register any VA for small loads?Strange, the borrowed one is a P4400 and mine is a P4460.
They wouldn't both be bad.
I'm guessing "user error" But what could it be???
Amprobe is fine.
Ha, I just learned that libraries around my area 'lends' garden seeds (tomatoes, cucumbers, ...), small power tools and camping gear.My wife, the librarian, said Excel Energy donated two of them.
edit:
She also has 35 pair snow shoes to lend.....................................
They may be capacitive, but you can't tell that from a reading on the Kill-a-watt. The PF measurement on the Kill-a-watt doesn't distinguish between capacitive and inductive power factor.I've been testing cheap led bulb to decide whether to use a few in a building that has pf problem already.
Only a few, so it's not a big deal. Just on principle, I want to be going the right direction.
Even though they are bad. .55 pf it appears to be capacitive.
The led tubes I've been using are over .90.
Amprobe shows it to be capacitive, as I would expect. Cheapo driver seems to be a bridge, cap, zener, resistor combination across the line.They may be capacitive, but you can't tell that from a reading on the Kill-a-watt. The PF measurement on the Kill-a-watt doesn't distinguish between capacitive and inductive power factor.
Thanks, I may look into that. Just what I was hoping to hear.It's possible to make a hardware modification to the Kill-a-watt P4400 which will increase its sensitivity and make the measurement of "vampire" loads more accurate. My Kill-a-watt P4400 has an internal shunt consisting of a short piece of manganin wire. I bought another P4400 Kill-a-watt at Fry's, removed the shunt and measured it with a 4 wire ohmmeter. It's a 2 milliohm shunt. I then replaced that shunt with a .2 ohm, 2 watt 5% wirewound resistor, choosing the most accurate one from a bunch of them. Now the modified Kill-a-watt has 100 times the sensitivity. I was able to measure the no load draw of a modern wall wart at .077 watts. The maximum power measurable is now 18 watts. I compared the reading with my high sensitivity, low power factor Yokogawa wattmeter, and it was very close.
Some "Kill-a-watt" type meters, or other models of the Kill-a-watt brand, may not have a 2 milliohm shunt, but the P4400 I modified did have a 2 milliohm shunt.
For the final accuracy check, I just set the modified Kill-a-watt to measure current with a small purely resistive load, and compared that to the simultaneous current reading measured with a DVM. The modified Kill-a-watt reads 2% low. A person could trim the .2 ohm shunt, or just add 2% to the reading. To trim, I would start with a .2 ohm resistor that measured high with full length leads, as measured with a 4 terminal ohmmeter, solder in the resistor with near full length leads, and then shorten them as a method of trimming. Or, solder in a .22 ohm resistor and solder in an additional resistor(s) in parallel to trim.
What model Amprobe is that?Amprobe shows it to be capacitive, as I would expect. Cheapo driver seems to be a bridge, cap, zener, resistor combination across the line.
by Duane Benson
by Aaron Carman
by Aaron Carman
by Aaron Carman