size of generator

[buickanddeere]

The VFD can be set with a max amperage and it will keep adding voltage as the resistance drops until the heaters are at rated output. All without human intervention and error.

 

[SPYDERLK]

The VFD can be set with a max amperage and it will keep adding voltage as the resistance drops until the heaters are at rated output. All without human intervention and error.

Cool!

 

[Richard]

These are incandescent heaters. Inrush to a 100W bulb is 13A, dropping to 0.8A as the filament heats -- a 16 fold drop.

Since this electrical theory is above my head, I'm not commenting on that..however, from a mathematical point of view, if you go from 13A to 1A, that represents a 92% reduction... not a 16-fold.

Once you have a "1-fold" (100%) reduction, you are at zero, no??

My pardons if I'm misunderstanding something.

 

[Mendonsy]

13 / 0.8 = 16.25 so the math is fairly simple. From there you can call it whatever you want I suppose.

 

[arrow]

Why go complicated with a hand operated mechanical switch and having to train everyone to operate it ? Just use a VFD to ramp up voltage and current .

B&D, any idea of the percentage of inrush reduction possible with a vfd?

 

[buickanddeere]

B&D, any idea of the percentage of inrush reduction possible with a vfd?

Not really the way to ask the question in percent.
The usual 140amp current inrush would have a continuous running heating current of lets guess 14.0 amp. VFD set to limit current to perhaps 35.0 amps for example and would possibly heat the coils to rated temp, voltage and then the heaters would self limit to the estimated 14.0 amps. .
If this is even a workable solution ??? A lot of "what if's" with limited info.

 

[Richard]

13 / 0.8 = 16.25 so the math is fairly simple. From there you can call it whatever you want I suppose.

Indeed...the math is simple. I get amazed at times when folks don't get it.

If you have $100 and drop to $50, you have dropped 50% If you drop to 80 cents, you have dropped 99.2%

((50-100)/100) = -50%


If you have $50 and jump up to $100, you gained 100%

Once you drop 100% you have by definition gone to zero so, as an aside, what is 100X16?.... me thinks it's 1,600, not a fraction.

You can call it whatever you want but you are displaying a misunderstanding of basic math (although your fraction above is accurate, 13/.08 = 16.25 that wasn't the comment). The comment was that it was a 16X drop when it's actually a 99.385% drop.

I "get" what was being said....it's just that it was mathematically out of whack and I wanted to guide it back to a more real number.

(I drive my wife nuts as people are ALWAYS making this mistake and I catch it almost every time)

 

[SPYDERLK]

Indeed...the math is simple. I get amazed at times when folks don't get it.

If you have $100 and drop to $50, you have dropped 50% If you drop to 80 cents, you have dropped 99.2%

((50-100)/100) = -50%


If you have $50 and jump up to $100, you gained 100%

Once you drop 100% you have by definition gone to zero so, as an aside, what is 100X16?.... me thinks it's 1,600, not a fraction.

You can call it whatever you want but you are displaying a misunderstanding of basic math (although your fraction above is accurate, 13/.08 = 16.25 that wasn't the comment). The comment was that it was a 16X drop when it's actually a 99.385% drop.

I "get" what was being said....it's just that it was mathematically out of whack and I wanted to guide it back to a more real number.

(I drive my wife nuts as people are ALWAYS making this mistake and I catch it almost every time)

A drop to one sixteenth is a 94% drop. -- 13 vs 0.8 ... NOT .08