Kill A Watt Fun and Observations

[sockpit]

I'm posting these observations here because everything I know about power I've learned from Alex C. and John S.

 

I live in the Bay Area and my power company has contracted with a Home Energy Audit firm to take advantage of the very smart smart meters now used in my condo complex.  I get monthly reports using algorithms to provide me with a detailed profile of my home's usage.  I recently learned that I'm using twice as much in the Base Electric category as other similar homes in my area.  So I bought a Kill A Watt to find the culprit.

 

My fear was that my system (which I leave on 24/7 for the usual reasons) was a major culprit.  While it does use more than most of the things I have running all the time (except of course for refrigerators), I was surprised to learn that it registers a constant 50-65 watts, regardless of whether it's playing music or not.  That's like running a single incandescent bulb all the time--and given the value of music to me, I can live with that "waste," so long as I can cut out all other unnecessary offenders.  Turning everything off to save that wattage is a pain, since my entire system is more like a bunch of little computers booting than anything else.

 

Here's my power chain:  

 

-Topaz (small 500VA) Iso transformer to a) JS-2 linear PSU and b) my Exogal Ion amplifier (via its large Meanwell SMPS).  

-The JS-2 feeds a) my Exogal Comet DAC (which works in tandem with the Ion via its single HDMI cable--pretty cool) and b) my LPS-1 (overkill, I know), which in turn, feeds my uRendu.

 

Surprises:

 

I'm surprised a) by just how few watts the whole system draws, especially while I'm playing music (in a small room, mind you).  It draws just 65 watts when blasting away.  I was once worried that my 500VA Topaz would be too small.  But it seems enormous relative to the actually power usage.  Am I thinking rightly about this?

 

b) I'm surprised it draws about the same 50-65 watts when silent, maybe a couple more on avg.  I think the JS-2 and LPS-1 draw the most; they remain warm when on (perhaps Alex has some figures on their standby usage.)  In any case the Kill O Watt (into which the Topaz is plugged) cycles constantly between about 50 and 65 and I imagine that is because the ultra capacitors in the LPS-1 are cycling. Is that correct?

 

As you can probably tell, I'm not an EE.  Any light that can be shed on why playing loud makes so little difference is appreciated!  Perhaps its the benefit of the Exogal PowerDac concept, which keeps even amplification in the digital realm as long as possible . . . ?  I was indeed surprised by the Ion's Meanwell when I purchased it.

 

 

 

 

 

[Ralf11]

The Kill-A-Watt samples, and may do some averaging, but does not measure quick transients.  So, VAr may be greater than shown.

 

 

[Speedskater]

Neither the 'Kill-a-Watt' nor the power meter, measures quick music transients.

My old TV Set-Top-Box draws about the same 25 Watts whether it's on or in stand-by.

Power conservation people call this phantom power and there are now rules to reduce this waste.

[KingRex]

I watched the power meters on a Dartzeel monoblocks pushing 9 foot tall Evolution speakers peak at 18 Watts.  That's peak. Really knothing.  

Class A or A /B amps or tube amps at idle are quite hot.  That's all wasted energy.  My topaz transformer waste 7% at idle. Your 500 watt tran calc is 500x24x30x$.10/1000.  $.10 guess at utility cost.  That's transformer waste.  

[One and a half]

1 hour ago, KingRex said:

I watched the power meters on a Dartzeel monoblocks pushing 9 foot tall Evolution speakers peak at 18 Watts.  That's peak. Really knothing.  

Class A or A /B amps or tube amps at idle are quite hot.  That's all wasted energy.  My topaz transformer waste 7% at idle. Your 500 watt tran calc is 500x24x30x$.10/1000.  $.10 guess at utility cost.  That's transformer waste.  

That calculation is at full rating of the Topaz. Try  and replace the 500 with 7% of 500. Is that 7% measured at no load?

 

Transformers require watts to produce no real work, these are reactive , measured in VAr. Don’t confuse the issue with efficiency. Transformers efficiency is usually in the high 90% at full rating.  

 

My 2500 VA Topaz has its work cutout when starting the power amp, a larger transformer is necessary for this aspect alone which at idle consumes more VAr than a 500VA.

 

I’m wondering whether the OP is being charged for VAr? 

[sockpit]

I’m not familiar with the concept of reactive VAr, so I’m not sure how to answer.

 

The kill-a-watt measurement given above was at the outlet, so included all components, including the small Topaz.  I’ll play and see what the Topaz alone draws.  It is warm, but so are the JS2, LPS1, and Ion when on 24/7.

 

Still surprised the whole thing playing doesn’t draw more power.

 

Thanks for the replies.

[Ralf11]

a reactive load is anything with inductance and/or capacitance (i.e. almost everything that uses electricity)

 

think of resistance as a simplified version of  reactance, an ideal (which you can get away with sometimes)

[One and a half]

1 hour ago, sockpit said:

I’m not familiar with the concept of reactive VAr, so I’m not sure how to answer.

 

The kill-a-watt measurement given above was at the outlet, so included all components, including the small Topaz.  I’ll play and see what the Topaz alone draws.  It is warm, but so are the JS2, LPS1, and Ion when on 24/7.

 

Still surprised the whole thing playing doesn’t draw more power.

 

Thanks for the replies.

The killawatt has a readout of VA and kW. The vector difference between the 2 is the power factor , angle wise.

kW are always at 1.00 and the kW are at kVA x the power factor. Easy! Yeah right.

 

kW is usually what you pay for unless it’s seperatly shown on your bill otherwise.

kWHr actually, it’s time based. 

 

Revenue meters are very accurate but I really wonder how accurate when the current distortion can be such it doesn’t look like a sine wave any more. No doubt the power company works that out in their favour.