Plug in Power Meter

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GazWrack

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Thought this would be useful for people wanting to buy a UPS but don't know what size to get...

I posted a thread a while ago about my ups inverter that exploded and the subsequent drama with the guy I bought it from. (I was accused of overloading the unit)
Anyway, I went on a mission determined to find out exactly how much power my set up was drawing in order to end the argument once and for all. This led me to a shop in Boksburg that sold me one of these for R210:

http://www.radiant.co.za/?page=Product&id=06se30&group=

It shows the volts, amps, and watts of whatever is plugged into it at the time.

As it turns out, my PC, 2 LCD monitors, light, router, and radio only pull 0.86 - 1.16 amps which is surprising, I thought it would be more. But at least I know I wasn't wrong about my previous inverter not being overloaded.
 
GazWrack said:
Thought this would be useful for people wanting to buy a UPS but don't know what size to get...

I posted a thread a while ago about my ups inverter that exploded and the subsequent drama with the guy I bought it from. (I was accused of overloading the unit)
Anyway, I went on a mission determined to find out exactly how much power my set up was drawing in order to end the argument once and for all. This led me to a shop in Boksburg that sold me one of these for R210:

http://www.radiant.co.za/?page=Product&id=06se30&group=

It shows the volts, amps, and watts of whatever is plugged into it at the time.

As it turns out, my PC, 2 LCD monitors, light, router, and radio only pull 0.86 - 1.16 amps which is surprising, I thought it would be more. But at least I know I wasn't wrong about my previous inverter not being overloaded.
Click to expand...

Tried calling Radiant a few weeks back and they didn't have stock. Also called Discount Electrical in Boksburg and they don't have this one.
Any idea where to get it from?
 
GazWrack said:
Thought this would be useful for people wanting to buy a UPS but don't know what size to get...

I posted a thread a while ago about my ups inverter that exploded and the subsequent drama with the guy I bought it from. (I was accused of overloading the unit)
Anyway, I went on a mission determined to find out exactly how much power my set up was drawing in order to end the argument once and for all. This led me to a shop in Boksburg that sold me one of these for R210:

http://www.radiant.co.za/?page=Product&id=06se30&group=

It shows the volts, amps, and watts of whatever is plugged into it at the time.

As it turns out, my PC, 2 LCD monitors, light, router, and radio only pull 0.86 - 1.16 amps which is surprising, I thought it would be more. But at least I know I wasn't wrong about my previous inverter not being overloaded.
Click to expand...

Some one smarter correct me if im wrong but that would be 0.86 -1.16 amps over 220 Volts - the amperage goes up when the voltage decreases so the UPS would have been 12 or 24 V - SO rough calculation im guessing you running 350 Watts which over 24 Volts would have been like 15 Amps, and over 12 Volts 30 amps
 
isie said:
Some one smarter correct me if im wrong but that would be 0.86 -1.16 amps over 220 Volts - the amperage goes up when the voltage decreases so the UPS would have been 12 or 24 V - SO rough calculation im guessing you running 350 Watts which over 24 Volts would have been like 15 Amps, and over 12 Volts 30 amps
Click to expand...

Correct, the higher the voltage the lower the current required to push a certain wattage.

As an aside:
Yanks use 110V, less chance of electrocution but higher amps so more fire risk(in wooden houses which is just idiotic)
We use 220V, higher chance of electrocution but lower fire risk
Cars use 12V so people don't get zapped every time they touch anything metal.
 
isie said:
Some one smarter correct me if im wrong but that would be 0.86 -1.16 amps over 220 Volts - the amperage goes up when the voltage decreases so the UPS would have been 12 or 24 V - SO rough calculation im guessing you running 350 Watts which over 24 Volts would have been like 15 Amps, and over 12 Volts 30 amps
Click to expand...

That got me very confused, can someone explain it in more detail? I really don't understand how 350w could draw so much current, unless I have the wrong end of the stick?
 
thechamp said:
That got me very confused, can someone explain it in more detail? I really don't understand how 350w could draw so much current, unless I have the wrong end of the stick?
Click to expand...

remember:
Input Power = losses + Output Power
Power=VxI (assuming resistive load)
losses = about 10%

So, if Output Power = 350W
Then Input Power = 0.1 x 350 + 350 = 385W = V x I = 12 x I (if 12V input voltage)
thus:
385 = 12 x I
and I = 385/12 = 32A
or if input voltage = 24V
I = 385/24 = 16A
 
Bundu said:
remember:
Input Power = losses + Output Power
Power=VxI (assuming resistive load)
losses = about 10%

So, if Output Power = 350W
Then Input Power = 0.1 x 350 + 350 = 385W = V x I = 12 x I (if 12V input voltage)
thus:
385 = 12 x I
and I = 385/12 = 32A
or if input voltage = 24V
I = 385/24 = 16A
Click to expand...

That's better thanks, so the high current is on the input side of the inverter, right? meaning the current drawn from the batteries, not the current drawn by the appliances on the AC side?

So the story about overloading causing the UPS to explode does not really add up.
 
Last edited:
That's correct - it blowing up (or blowing a fuse rather) would happen if the rating is exceeded
 
Thor187 said:
My PC has a 1200 PSU it's the only "big" bastard I want to test besides the Fridge so should be fine?
Click to expand...

1200 is your PSU's capacity. Well, if it's 80% efficient then closer to 1000w. That's the max it will draw - it depends on your other gadgets - MB, GPU, CPU, HDD, etc.
 
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