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Old 01-01-2005, 05:12 PM   #21
BarraCuda™
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Quote:
Originally Posted by deep_end
Bro,

I JUST knew it was too good to be true.

So, in general is the PF of 0.7 a conservative enough figure to work with, or is this limited to most pumps? And is 10% a reasonable power loss for an inverter?
depending .. there is no sure way of telling the power factor without actual measurement. Some pumps comes with a rated ampere so you may take reference from there. Resun MD55 is rated at 130watts but consumes ~0.8A.

If the pump does not come with the specs .. you may take it to have a power factor of 0.7 or lower. Its better to overdesign than underdesign.

10% power loss is reasonable for a good inverter .. again depending on the quality of it. May range from 10% to 30%
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Old 01-01-2005, 10:11 PM   #22
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Originally Posted by BarraCuda™
then its not worth it anymore .. using a 270Ah battery will yield abt 3000VA .. much much more than 1000VA
oh .. didn't read the 270Ah ...
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Old 03-01-2005, 05:03 PM   #23
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Bro,

Quote:
Originally Posted by BarraCuda™
depending .. there is no sure way of telling the power factor without actual measurement. Some pumps comes with a rated ampere so you may take reference from there. Resun MD55 is rated at 130watts but consumes ~0.8A.
so in this case, 0.8A = 192W (based on 240V), is this current draw more accurate than the pump consumption of 130W? If a clamp-meter is used, will it show amps or watts?

Quote:
Originally Posted by BarraCuda™
If the pump does not come with the specs .. you may take it to have a power factor of 0.7 or lower. Its better to overdesign than underdesign.

10% power loss is reasonable for a good inverter .. again depending on the quality of it. May range from 10% to 30%
Hmm, OK, gotcha, thanks.
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Old 03-01-2005, 05:53 PM   #24
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Quote:
Originally Posted by deep_end
Bro,


so in this case, 0.8A = 192W (based on 240V), is this current draw more accurate than the pump consumption of 130W? If a clamp-meter is used, will it show amps or watts?


Hmm, OK, gotcha, thanks.
Yes, the current draw is 0.8A = 192w = apparent power (VA).
Higher because of the reactive power.
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Old 03-01-2005, 11:44 PM   #25
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Quote:
Originally Posted by deep_end
Bro,


so in this case, 0.8A = 192W (based on 240V), is this current draw more accurate than the pump consumption of 130W? If a clamp-meter is used, will it show amps or watts?

cwloo is correct, the actual ampere drawn will be ~0.8A due to reactive power. Clampmeter will only show amperes/voltage.

I took a actual measurement of my resun MD55, its abt ~0.9A which is higher than the rated 0.8A.

So 0.9A X 240V = 216VA

Assuming the rated wattage is correct

130watts/216VA = powerfactor = 0.6
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Old 04-01-2005, 06:35 PM   #26
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That's not very efficient, is it?

I think not many people (like me) realize this. And think that 1 VA = 1 W. To certain extent, the specs on the label is a case of misrepresentation. As far as power consumption is concerned, we're only paying for the 130W and not the 216VA, right?
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Old 04-01-2005, 07:15 PM   #27
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Quote:
Originally Posted by deep_end
That's not very efficient, is it?

I think not many people (like me) realize this. And think that 1 VA = 1 W. To certain extent, the specs on the label is a case of misrepresentation. As far as power consumption is concerned, we're only paying for the 130W and not the 216VA, right?
yes, we are only paying for the 130W if the its rated correctly. Now to drop another bomb .. the back pressure may have an effect on power consumption. Some pumps they publish load/wattage charts where it shows the actual power consumption under specific loads.

Now .. resun MD55 is rated at 130W but at what load? Max load? Min load? My guess is that the resun MD55 is rated at the max load/min wattage while iwaki is rated at min load/max wattage.

Taken from a post from Roidan in SRC


The power consumption of the pump increases when the flowrate is higher! Roidan measured a 0.95A for his MX100 while I got ~0.9A for my resun MD55? Fishy isnt it?

If I based on the rated 130watts and calculate the monthly kWh costs, it doesnt tally with the actual increased in electricity bills!

So now, we realised that using a pressure rated pump for non-pressure rated application isnt really a good thing. You got less flow per hr and get higher electrical bills!
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Old 06-01-2005, 12:51 AM   #28
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Ah so!!!! No wonder my electricity bill estimates never seem to tally with the real thing. Damn !!!
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Old 06-01-2005, 07:16 PM   #29
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Renaming this thread to UPS and power consumption
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Old 07-01-2005, 12:15 AM   #30
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ah! time to get rid of my md55! but how about my beckett? alamak!
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