How to measure 121 Giga Watts with a 121GW meter ?

[ez24]

Hi

Ever since I read that the 121GW meter is based on a 121 Giga Watt statement in a movie, I have wondered how someone could measure 121 Giga Watts.   My guess is measure the voltage drop across a shunt.  With 121 GW my guess a shunt the size of an aircraft carrier would be needed.

So how can you measure 121 GW with a 121GW?  I assume you cannot just use the leads that come with the meter. 

As a rough estimate, the US generates about 4,000 terawatt-hours (TWh) a year

Terabyte = 1,024 Gigabytes

So the US uses less than 121 GW a year.

I think the first thing is limit the voltage to the voltage limit of the meter, so no million volts..   So I wonder if a 10 foot diameter bus bar would work?

Any math wizards?

[WastelandTek]

meh, its nothing compared to the Disaster Area show I was just at

[rs20]

You do not measure power with 2 leads, you need 3 or 4 leads. This is because power = voltage * current, you need to measure voltage and current independently.

A (large?) nuclear reactor generates approximately 1.21 GW.

Assuming DC power, and a max voltage of 600 VDC, we'd be dealing with 200 MA (megaamps). Now clearly the meter cannot handle 200MA, but let's assume the shunt in the meter is 10 milliohms. If we put a a 0.1 nanoohm resistor in parallel with that shunt, we'd have 2A running through the meter when the 0.1 nanoohm shunt is dealing with 200MA; and it's scale accordingly. The display on the meter would simply be "off" by a factor of 100,000,000, simply place a sticker over the 10A switch labelled "1GA" and read the meter accordingly, and you're good to go.

The 0.1 nanoohm shunt will dissipate 4 MW. Good quality cooling would be encouraged.

If you ever encounter 1.21GW, it's much more likely to be 121 kV * 10 kA. This would actually be "quite straightforward" to measure, provided you could arrange a similar voltage divider as well as a current "splitter/divider". The shunt, 2 microohm, would dissipate much less heat: a completely manageable 200 W.

You'd need to measure voltage and current separately, the 121GW probably doesn't have a power measurement mode where it multiplies the two for you. A metrahitt-whatever-it's-called could do that job, though, with suitable stickers redefining what the voltage, current and power ranges mean.

[Brumby]

Terabyte = 1,024 Gigabytes

Ah ... Correction.  It is only in computer circles that the Giga/Tera factor is 1024 - just because they like their powers of 2.**

Engineers do it right ... it's 1,000.


** Actually, even in computer circles that is not consistent.  Sometimes you will find - especially in the marketing department - someone will use a factor of 1,000 so they can describe (typically hard drives) as having a 1 TB capacity when it holds less than 1024*1024*1024*1024 bytes.  It gets even more bizarre when they use a mix of 1,000 and 1024.

[Tom45]

If someone gave me the task of measuring 121GW, I'd tell them once they get 121GW through a single transmission line get back to me and I'll then start thinking about how to measure it. I wouldn't expect to hear from them again.

[IanMacdonald]

I'm reasonably sure that the Smiths car dashboard instruments go up to 55GW, so they probably make higher ranges too.

http://gridwatch.templar.co.uk/   

Most likely the current -which is the problematic quantity- would be measured with a current transformer. Straight bar primary, multiturn secondary. Or, a hall effect device could measure the magnetic field near the conductor. Not so accurate, but works for DC.

Voltage, just f'ing great potential divider resistor, likely the type with rain shielding discs on it.

Though, 121GW is more than double the UK peak demand.

[boffin]

Terabyte = 1,024 Gigabytes

Actually the 2^10 (1024) multipliers are:
 Tebi(byte),
 Gibi(byte),
 Mebi(byte),
 Kibi(byte)

per the IEC.
https://en.wikipedia.org/wiki/Kibibyte

[Ampera]

Terabyte = 1,024 Gigabytes

Actually the 2^10 (1024) multipliers are:
 Tebi(byte),
 Gibi(byte),
 Mebi(byte),
 Kibi(byte)

per the IEC.
https://en.wikipedia.org/wiki/Kibibyte

This is correct. The SI multipliers are 1000s of the previous one i.e.

1 Kilobyte = 1000 bytes
1000 Megabyte = 1000 Kilobytes

etc

This also repeats for bits which is a more (pure?) measurement of data.

1 byte = 8 bits
1 Kilobit = 1000 bits
1 Megabit = 1000 Kilobits

etc.

The IEC has set down a standard (which basically turned into a situation of good luck with that) that are supposed to signify the powers of 2 deal. At this point it's largely arbitrary, but you have to be careful, as many people (Like the OP) have their own standards, which are technically wrong, but understandably so because so many people have said so many different things, it's confusing to no end.

As boffin said, the first two letters of the standard SI multipliers are used, followed by bi (Kibi, Mebi, Gibi, Tebi, Pebi etc.) the same will then follow for byte vs bit mesaures

1 byte = 8 bits

1 Kibibyte = 1024 bytes & 1 Kibibit = 1024 bits
1 Mebibyte = 1024 Kibibytes & 1 Mebibit = 1024 Kibibits

The distinction is for the most part unnecessary unless you are dealing with lower level stuff that would make the IEC standard your best friend. For your average flash stick or hard drive however, it's not that big of a difference, even if it is confusing, for most people.

[ebastler]

As a rough estimate, the US generates about 4,000 terawatt-hours (TWh) a year
Terabyte = 1,024 Gigabytes
So the US uses less than 121 GW a year.

You have your units mixed up there, confusing power and energy.

The total "consumption" of electrical energy in the U.S. is 4,000 TWh per year. You have to divide that by the number of hours per year to get the average power:
(4,000 TWh/a) / (24*365 h/a) =  0.456 TW = 456 GW.

So the United States provide a convenient DUT to test an even stronger meter than the 121GW. 

[Avacee]

The actual value in the film is 1.21 GW ... your task just got 100 times easier

[Zero999]

You do not measure power with 2 leads, you need 3 or 4 leads. This is because power = voltage * current, you need to measure voltage and current independently.

A (large?) nuclear reactor generates approximately 1.21 GW.

Assuming DC power, and a max voltage of 600 VDC, we'd be dealing with 200 MA (megaamps). Now clearly the meter cannot handle 200MA, but let's assume the shunt in the meter is 10 milliohms. If we put a a 0.1 nanoohm resistor in parallel with that shunt, we'd have 2A running through the meter when the 0.1 nanoohm shunt is dealing with 200MA; and it's scale accordingly. The display on the meter would simply be "off" by a factor of 100,000,000, simply place a sticker over the 10A switch labelled "1GA" and read the meter accordingly, and you're good to go.

The 0.1 nanoohm shunt will dissipate 4 MW. Good quality cooling would be encouraged.

If you ever encounter 1.21GW, it's much more likely to be 121 kV * 10 kA. This would actually be "quite straightforward" to measure, provided you could arrange a similar voltage divider as well as a current "splitter/divider". The shunt, 2 microohm, would dissipate much less heat: a completely manageable 200 W.

You'd need to measure voltage and current separately, the 121GW probably doesn't have a power measurement mode where it multiplies the two for you. A metrahitt-whatever-it's-called could do that job, though, with suitable stickers redefining what the voltage, current and power ranges mean.

Except shunts wouldn't be used to measure such high currents. A hall effect sensor is normally the method of choice for measuring such high currents because there's hardly any power loss.

[G0MJW]

Hi

Ever since I read that the 121GW meter is based on a 121 Giga Watt statement in a movie, I have wondered how someone could measure 121 Giga Watts.   My guess is measure the voltage drop across a shunt.  With 121 GW my guess a shunt the size of an aircraft carrier would be needed.

So how can you measure 121 GW with a 121GW?  I assume you cannot just use the leads that come with the meter. 

As a rough estimate, the US generates about 4,000 terawatt-hours (TWh) a year

Terabyte = 1,024 Gigabytes

So the US uses less than 121 GW a year.

I think the first thing is limit the voltage to the voltage limit of the meter, so no million volts..   So I wonder if a 10 foot diameter bus bar would work?

Any math wizards?

I thought it was 1.21 GW. 

Its not an unachievable  amount of power, my local power station generates 1.36GW but that's OK as its not likely to be travelling at 88mph unless something has gone seriously wrong in the turbine hall. The associated 750kV transmission lines are typically carrying several GW of power.

As far as measuring GW power transfers, "from a distance" comes to mind. Either that or get someone else to do it http://www.gridwatch.templar.co.uk/ . You don't need a shunt to measure current in a transmission line, you can measure the magnetic field and electric field. This is much easier if it is AC because you only need to measure the varying component.

Mike

[German_EE]

Measure the voltage at the power station end of the transmission line

Measure the voltage at the load end of the transmission line

Watts = Voltage Drop ^2 / Line Resistance

[Yansi]

Terabyte = 1,024 Gigabytes

Actually the 2^10 (1024) multipliers are:
 Tebi(byte),
 Gibi(byte),
 Mebi(byte),
 Kibi(byte)

per the IEC.
https://en.wikipedia.org/wiki/Kibibyte

Fuck the the IEC with this. Hate this shit hard.  Used kB as 1024B, MB as 1024kB ever since and will continue doing so. Not interested in the KiD, sorry, KiB stuff. 

[skarecrow]

The actual value in the film is 1.21 GW ... your task just got 100 times easier

Actually in the movie it was jigga-watt. :-P

Sent from my XT1565 using Tapatalk

[rstofer]

Measuring the 1.21 GW power as 121 kV at 10,000 Amps is trivial.  We simply use a 10,000:5 current transformer and a 150 kV:120V voltage transformer.

http://new.abb.com/high-voltage/instrument-transformers

Therefore, split the 121 GW into 100 parallel paths, measure the voltage once and measure the current 100 times.

Maxwell would be proud of the fields surrounding the measuring station.

[skarecrow]

Terabyte = 1,024 Gigabytes

Actually the 2^10 (1024) multipliers are:
 Tebi(byte),
 Gibi(byte),
 Mebi(byte),
 Kibi(byte)

per the IEC.
https://en.wikipedia.org/wiki/Kibibyte

Fuck the the IEC with this. Hate this shit hard.  Used kB as 1024B, MB as 1024kB ever since and will continue doing so. Not interested in the KiD, sorry, KiB stuff. 

Damn right! 1k has been 1024 since I started writing my own games in Commodore BASIC on my C64 when I was 4 years old. 1k will always be 1024 in my book, I don't care what your book says. Y2K is still over 30 years in the future!!!  I can just about guarantee the year 2048 brings about a LOT more computer problems than the year 2000 did.

Another thing I noticed in the OP (sorry I can't easily do 2 quotes on my phone) is a little math error.  Here is the quote...


As a rough estimate, the US generates about 4,000 terawatt-hours (TWh) a year

Terabyte = 1,024 Gigabytes

So the US uses less than 121 GW a year.


Someone else already mentioned getting the units mixed up. I think 4000*1024 is a little more than 121. 4000TW==4,096,000GW. So obviously the US uses more than 121(1.21)GW/GWh/whatever. I think the OP read it backwards or something.

Sent from my XT1565 using Tapatalk

[Zero999]

Terabyte = 1,024 Gigabytes

Actually the 2^10 (1024) multipliers are:
 Tebi(byte),
 Gibi(byte),
 Mebi(byte),
 Kibi(byte)

per the IEC.
https://en.wikipedia.org/wiki/Kibibyte

Fuck the the IEC with this. Hate this shit hard.  Used kB as 1024B, MB as 1024kB ever since and will continue doing so. Not interested in the KiD, sorry, KiB stuff. 

Damn right! 1k has been 1024 since I started writing my own games in Commodore BASIC on my C64 when I was 4 years old. 1k will always be 1024 in my book, I don't care what your book says. Y2K is still over 30 years in the future!!!  I can just about guarantee the year 2048 brings about a LOT more computer problems than the year 2000 did.

Another thing I noticed in the OP (sorry I can't easily do 2 quotes on my phone) is a little math error.  Here is the quote...


As a rough estimate, the US generates about 4,000 terawatt-hours (TWh) a year

Terabyte = 1,024 Gigabytes

So the US uses less than 121 GW a year.


Someone else already mentioned getting the units mixed up. I think 4000*1024 is a little more than 121. 4000TW==4,096,000GW. So obviously the US uses more than 121(1.21)GW/GWh/whatever. I think the OP read it backwards or something.

I can understand measuring RAM in KiB and MiB, as it is arranged in powers of 2, so it makes sense and numbers easier to write. However, I think it's confusing for other things such as current and power, which don't normally occur in powers of 2.

I think you'll be fine here if you refer to memory as 1KB = 1024B but you'll get flamed if you start using it for Ohms. 

[skarecrow]

Terabyte = 1,024 Gigabytes

Actually the 2^10 (1024) multipliers are:
 Tebi(byte),
 Gibi(byte),
 Mebi(byte),
 Kibi(byte)

per the IEC.
https://en.wikipedia.org/wiki/Kibibyte

Fuck the the IEC with this. Hate this shit hard.  Used kB as 1024B, MB as 1024kB ever since and will continue doing so. Not interested in the KiD, sorry, KiB stuff. 

Damn right! 1k has been 1024 since I started writing my own games in Commodore BASIC on my C64 when I was 4 years old. 1k will always be 1024 in my book, I don't care what your book says. Y2K is still over 30 years in the future!!!  I can just about guarantee the year 2048 brings about a LOT more computer problems than the year 2000 did.

Another thing I noticed in the OP (sorry I can't easily do 2 quotes on my phone) is a little math error.  Here is the quote...


As a rough estimate, the US generates about 4,000 terawatt-hours (TWh) a year

Terabyte = 1,024 Gigabytes

So the US uses less than 121 GW a year.


Someone else already mentioned getting the units mixed up. I think 4000*1024 is a little more than 121. 4000TW==4,096,000GW. So obviously the US uses more than 121(1.21)GW/GWh/whatever. I think the OP read it backwards or something.

I can understand measuring RAM in KiB and MiB, as it is arranged in powers of 2, so it makes sense and numbers easier to write. However, I think it's confusing for other things such as current and power, which don't normally occur in powers of 2.

I think you'll be fine here if you refer to memory as 1KB = 1024B but you'll get flamed if you start using it for Ohms. 

A general rule of thumb I go by, if it's computer related it's 1024, otherwise it's probably 1000. When it comes to y2k that is a computer related event, therefore 2048 is the correct year. That 1GB hard drive is supposed to have 1,073,741,824 bytes.

Not computer related, 1K ohm is 1000 and $50k is $50,000.

Sent from my XT1565 using Tapatalk

[ebastler]

When it comes to y2k that is a computer related event, therefore 2048 is the correct year.