# RMS or average current to determine resistoring heating?

P

#### Phil Allison

Jan 1, 1970
0
"Fred Bloggs Wanker "
You shouldn't be concerned with either one.

** My god - that is UTERLY ASININE !!

Power dissipation is the rate at which the resistor is converting
electrical to thermal energy in joules per unit of time. When the
periodicity is small compared to the thermal time constant of the heat
sink, then you can you can use the average value of joule dissipation per
cycle, because much like a low pass filter, the heat sink temperature will
not respond to the high frequency component of the thermal dissipation
profile, it will only respond to its DC value, and another way of saying
'DC value' is 'average'. You might notice that computing average power
dissipation per cycle is the exact same thing as computing RMS current and
multiplying by R. Forget about the formulas and consider what it is you
really want to know.

** The OP has a much clearer idea of what HE needs to know than you !!

SO PISS OFF

YOU POSTURING, AUTISTIC FUCKWIT

....... Phi

P

#### Phil Allison

Jan 1, 1970
0
"Mook Johnson"
Yup had the same problems you discribe. Was using 4AH gell cells and the
90 boat would start relaibly. Switched to low impedance 7.5Ah gell cells
(low internal resistiance) and that went away but the field pack got
heavy.

We run 50% - 60% nitro and the plugs are COLD and we run rich. So we need
the 4 - 5A get them glowing. I had a setup that used a Alkaline D cell
for lighter. Worked well but then I "graduated" to a power panel.

** If you want to build the BEST glow plug driver possible

- see ABSE under " Glow Plug Regulator ".

This circuit regulates the TEMPERATURE of the platinum wire under all
conditions, whether the plug is dry and out of the engine, wet with fuel or
if the engine is idling or screaming.

The amp meter will allow you to tell if the plug is wet, blown, the mixture
is too lean or too rich.

What luxury - eh ?

I used one for many years, it really helped with getting quick engine starts
and consistent mixture settings.

........ Phil

F

#### Fred Bloggs

Jan 1, 1970
0
Phil said:
The average current draw from the 12 volt battery is then 50/100 =
0.5 mp - while the glow plug has 5 amps rms flowing through it.

Really? And you call this "dramatic," like there has been some kind of
current amplification effect taking place there, the battery supplying
one current and the glow plug seeing another? Since the current is the
same everywhere in the circuit, the battery and glow plug currents are
the same. The battery supplies 0.5A average, and the glow plug receives
0.5A average, and conversely, in order for the glow plug to receive
5Arms, the battery must supply 5A,rms. Where is the miracle there? In
any pulsed current system, Iavg=Ipk*D, and Irms=Ipk*sqrt(D) so that
Irms/Iavg=1/sqrt(D) which is always >1.

P

#### Phil Allison

Jan 1, 1970
0
"Fred Bloggs Terminal Fucking Cunthead "

** What happened to all the other stuff I wrote on this ?

Funny how such pointy headed autistic freaks MISS the point all the time.

........ Phil

M

#### Mook Johnson

Jan 1, 1970
0
Phil Allison said:
** If you want to build the BEST glow plug driver possible

- see ABSE under " Glow Plug Regulator ".

This circuit regulates the TEMPERATURE of the platinum wire under all
conditions, whether the plug is dry and out of the engine, wet with fuel
or if the engine is idling or screaming.

The amp meter will allow you to tell if the plug is wet, blown, the
mixture is too lean or too rich.

What luxury - eh ?

I used one for many years, it really helped with getting quick engine
starts and consistent mixture settings.

....... Phil

Sweet circuit.

I'll have to give it try.

T

#### Terry Given

Jan 1, 1970
0
pretty much:

perhaps you meant: Irms = Ipeak *sqrt(duty cycle) for a square wave....

thats quite an impressive typo

Actually, aside from being wrong, its also dreadfully ambiguous (use
average what?), which will doubtless confuse most who read it.

F

#### Fred Bloggs

Jan 1, 1970
0
Phil said:
"Fred Bloggs Terminal Fucking Cunthead "

** What happened to all the other stuff I wrote on this ?

Funny how such pointy headed autistic freaks MISS the point all the time.

You're the one with information retention deficit (IRD), and this is
more than obvious from your uninformative blather. I usually do not
stoop to discussing fundamental definitions or concepts with nitwits,
but made an exception in this case, to confirm once again that you're
uneducable...

P

#### Phil Allison

Jan 1, 1970
0
"Fred Bloggs Terminal Fucking Cunthead "

** What happened to all the other stuff I wrote on this ?

Funny how pointy headed, autistic freaks MISS the point all the time.

LOL

........ Phil

F

#### Fred Bloggs

Jan 1, 1970
0
Phil said:
"Fred Bloggs Terminal Fucking Cunthead "

** What happened to all the other stuff I wrote on this ?

Funny how pointy headed, autistic freaks MISS the point all the time.

LOL

The LOL is on you Miss Priss, you're the object of this discussion...

J
Replies
76
Views
13K
Steven Swift
S
Replies
10
Views
427
Replies
2
Views
1K
Replies
6
Views
2K
Replies
6
Views
2K