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-   -   Phantom load range? (http://www.diychatroom.com/f18/phantom-load-range-171157/)

langless28 02-05-2013 06:33 PM

Phantom load range?
 
In the grand scheme of things, is a 1.5-2.5A phantom load something outrageous? I know that ZERO is the goal but I was wondering if this is on the normal side or not?

Missouri Bound 02-05-2013 07:18 PM

To the best of my knowledge there isn't any measurable amperage on a wire which has phantom voltage. What voltage are you showing for this wire? In order for there to be amperage, there has to be a complete circuit. Phantom voltage can be present without a complete circuit.

langless28 02-05-2013 07:32 PM

I'm not referring to phantom voltage. I am referring to the current being used when everything is essentially off. there are things that even when off draw current. That is what I am referring to. I used a clamp ammeter to measure each leg of the 240v in when all switches/light are off in the house; allowing me to measure all the "stuff" that draws current while off and that I essentially pay for. That 1.5-2.5 amps being drawn 24/7 is about $15-30 / month!

Missouri Bound 02-05-2013 08:02 PM

Got it. The answer depends on the amount of electronic devices you have, there is no normal. All modern devices have a "warm up" circuit which keeps some parts energized for a faster turn on. If you want to invest in a TED, you could probable get a better handle on this. If you want to shave the electric expense use power strips everywhere and shut down everything. Personally I wouldn't do it, but that's just me.

langless28 02-05-2013 08:05 PM

I just just curious if anyone has measured it before and could relate.

ddawg16 02-05-2013 08:26 PM

It's easy to confirm if a voltage is phantom...put a load on it and the voltage goes away.......but current? No such thing as phantom current....there is a load somewhere.....and 1.5 to 2.5 is a lot of 'phantom'...your talking over 200 watts.....something is on.....you just have not found it yet.

mpoulton 02-06-2013 02:17 AM

That could be mostly reactive power, if the only loads are transformers and power supplies for things. The actual real power may be lower.

ddawg16 02-06-2013 09:48 AM

Quote:

Originally Posted by mpoulton (Post 1110670)
That could be mostly reactive power, if the only loads are transformers and power supplies for things. The actual real power may be lower.

Good point.....hence, 'how' the current is being measured comes into play.

mp....I'm assuming a good clamp on that is RMS would be the most accurate....right? If the OP was using one of those "Kilowatt" meter setups...I could see some error taking place...

langless28 02-06-2013 09:53 AM

I used a clamp on ammeter selected to the 4A range and clamped each 120v leg and then the ground to be sure I was getting an accurate reading. Now mind you I am saying this load equals all things that use power when everything is “off” for me personally. I do have a 30g fish tank heater and filter that runs 24/7 along with the usual tv, dvr, ps3, stereo, anything that has a clock, and probably half a dozen walwarts to various things.

AllanJ 02-06-2013 10:42 AM

The fish tank pump and filter system is a real load, not a phantom load. The fish tank heater probably cycles off some of the tme.

Also, the current drawn to power the clock on a VCR or microwave oven while it is "off" is real, not phantom.

Most wall warts draw some power while the device or appliance they serve are turned off. This, too is real, not phantom. This is due to less than perfect efficiency of a transformer. While the current drawn by a transformer (its primary winding) varies proportionately with the load drawn by the device it powers (from the secondary winding), when there is no secondary current, the primary current is not quite zero.

If you unplug all the wall warts and the microwave and the audio/video equipment and the fish tank (the fish won't die in a few minutes) and also flip off the breaker(s) that powers the doorbell and the furnace, what amperes reading to you get?

"Phantom" refers to the voltage that is induced in an otherwise dead wire because that wire is juxtaposed with a live wire, say, in the same Romex cable. The two wires and their insulation form a capacitor, which conducts some electricity, the higher the AC frequency, the better the conductance with the conductance theoretically zero for DC. Generally the longer the distance the wires are juxtaposed, the better the conductance of the "capacitor" they form. At 120 volts and 60 Hz the maximum current that will flow if you shorted the "dead" wire to ground is on the order of a milliampere or even less.

The act of measuring the voltage draws some current, typically a milliampere or so for an analog meter and microamperes for a digital meter. Usually the "voltage drop" across the "capacitor" for the current draw (the milliamperes) drawn by an analog voltmeter is so great that the meter registers zero for the phantom voltage.

mpoulton 02-06-2013 10:53 AM

Quote:

Originally Posted by ddawg16 (Post 1110823)
Good point.....hence, 'how' the current is being measured comes into play.

mp....I'm assuming a good clamp on that is RMS would be the most accurate....right? If the OP was using one of those "Kilowatt" meter setups...I could see some error taking place...

A clamp on ammeter only measures current, not power factor (since an in-phase voltage signal is needed for that, too). So a "kill-a-watt" type meter is actually what's needed to distinguish between real power and reactive power.


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