What is the power of an incandescent lamp at 200v 5A?

[SAC]

So,
if I collect two data streams (Volts and Amps) of instantanous (peak) values, and then perform the P=V*I calculations on these two data streams, producing a third data list, and then perform the RMS calculation on this list of Power points, what will I end up with.

Probably a waste of good data! Of what use is the RMS of the instantaneous power?

Given that data, you could calculate the real power, or the RMS power, or the power factor, or Z, or Q, or any number of other standard measurements that have standard meanings to people in the electrical industry.

 

[Electric-Light]

I hate to see this thread die, so I have a little twist...

I pulled a 40 watt 120v incandescent lamp off the shelf today and read through it with an ohmmeter.

how many ohms would you expect to read?

With a common meter such as a Fluke 87, I would guess around
30 to 45 ohms.

I measured it at 24.95 ohm.... a G25 globe, 40W 120v, "MEXICO". brand unknown, @ 10mA test current.

but we do not even know the range without specifications of the ohmmeter. Are we talking about very low current explosives igniter tester with <10mA testing current or are we talking about 1A+ testing current ohmmeter meant for for measuring contact resistance of huge industrial switches?

 

[Electric-Light]

Electric,
Electricians use steady state sine waves,

If all you ever deal with are heating elements and light bulbs powered by sinewave 60Hz voltage source, then you're right.

Add motors and you're still not far off, other than phase shift affecting the ability to calculate power.

How do you control the speed and torque of an AC motor? Wound rotor, slip rings connected to carbon pile variable resistor, duh. VFDs, PWMs, etc are not permitted!

 

[glene77is]

How do you control the speed and torque of an AC motor?
Wound rotor, slip rings connected to carbon pile variable resistor, duh.
VFDs, PWMs, etc are not permitted!

Electric,

Where are you going with that thought ?
I missed the logic.
'duh' is a personal attack.
"!" is not logical.
Are we broadening the playing field again ?

Are you simply saying that every solution still has its own problems ?

Are you pointing out, again,
that there is no final solution to your original question ?

 

[realolman]

With a common meter such as a Fluke 87, I would guess around
30 to 45 ohms.

I measured it at 24.95 ohm.... a G25 globe, 40W 120v, "MEXICO". brand unknown, @ 10mA test current.

but we do not even know the range without specifications of the ohmmeter. Are we talking about very low current explosives igniter tester with <10mA testing current or are we talking about 1A+ testing current ohmmeter meant for for measuring contact resistance of huge industrial switches?

Fluke 73.... 27.0 ohms

 

[Electric-Light]

Electric,

Where are you going with that thought ?
I missed the logic.
'duh' is a personal attack.
"!" is not logical.
Are we broadening the playing field again ?

Are you simply saying that every solution still has its own problems ?

Are you pointing out, again,
that there is no final solution to your original question ?

There is no final solution to original question UNTIL additional variables are specified. 200v RMS , 5A RMS... add "60Hz sine wave" and you have 1kW. Otherwise, the correct answer is C.

I apologize if I came across as rude.

What I was saying is that the statement below you made is far from truth today, because a significant part of electrical loads are solid state controlled. Power factor and harmonics corrected VSDs today may have front-end to make the input side current waveform pretty close to unity, but not perfect. Anything happens on load end.

Electricians deal with the load end too and electrical work between a drive and a 100kW switched reluctance motor is something still in the scope of electrician's work, unless you're going to say that wire A from motor goes to terminal A on drive, B to B, and so forth and that's it.

this is not a concept that any electrician uses.

Electricians use steady state sine waves,
and that means that we must broaden the base of inquiry.

 

[jumper]

There is no final solution to original question UNTIL additional variables are specified. 200v RMS , 5A RMS... add "60Hz sine wave" and you have 1kW. Otherwise, the correct answer is C.

I apologize if I came across as rude.

What I was saying is that the statement below you made is far from truth today, because a significant part of electrical loads are solid state controlled. Power factor and harmonics corrected VSDs today may have front-end to make the input side current waveform pretty close to unity, but not perfect. Anything happens on load end.

Electricians deal with the load end too and electrical work between a drive and a 100kW switched reluctance motor is something still in the scope of electrician's work, unless you're going to say that wire A from motor goes to terminal A on drive, B to B, and so forth and that's it.

So, your point is, after 246 posts on this subject, that the average sparky is either ignorant, stupid, or under trained?

Thanks.

I may get deleted, but I had to say it.

 

[glene77is]

Probably a waste of good data!
Of what use is the RMS of the instantaneous power?
Given that data, you could calculate the real power, or the RMS power, or the power factor, or Z, or Q, or any number of other standard measurements that have standard meanings to people in the electrical industry.

SAC,
I think you are right.
Electricians do not use the RMS concept in their craft,
"as standard meaning to people in the electrical industry."
Not for PF, or Z or Q.
My background is different.
Sac, Good point.
I've pointed to this in prior posts,
that the topic is headed towards an area which may be off topic.
That is the line of thought I was presenting.

I really don't think that Electric
will allow a final solution to the original problem.

 

[glene77is]

There is no final solution to original question UNTIL additional variables are specified. 200v RMS , 5A RMS... add "60Hz sine wave" and you have 1kW. Otherwise, the correct answer is C.

I apologize if I came across as rude.

What I was saying is that the statement below you made is far from truth today, because a significant part of electrical loads are solid state controlled. Power factor and harmonics corrected VSDs today may have front-end to make the input side current waveform pretty close to unity, but not perfect. Anything happens on load end.

Electricians deal with the load end too and electrical work between a drive and a 100kW switched reluctance motor is something still in the scope of electrician's work, unless you're going to say that wire A from motor goes to terminal A on drive, B to B, and so forth and that's it.

Electric,
Accepted.
Let us get on with the discussion.
I (also) have been criticized for being a
"disruptive factor in a blue-collar work group" for doing something similar;
ie, exploring the real science, to the distraction of regular working guys.
Let us get on with the discussion.

 

[Besoeker]

There is no final solution to original question UNTIL additional variables are specified. 200v RMS , 5A RMS... add "60Hz sine wave" and you have 1kW.

Would it be different at 50 Hz?

 

[Electric-Light]

Would it be different at 50 Hz?

Doubt it will be anything significant as far as the average power. It maybe possible to create measurable difference in a lab though.

 

[realolman]

Electric,
Accepted.
Let us get on with the discussion.
I (also) have been criticized for being a
"disruptive factor in a blue-collar work group" for doing something similar;
ie, exploring the real science, to the distraction of regular working guys.
Let us get on with the discussion.

We blue collars will go chew snuff or skin squirrels or somethin.

 

[robbietan]

v = 200v rms
i = 5A rms

no further information given

P = 1kW

rms = root mean square = equivalent dc

incandescent lamp = R with no XL or XC

frequency has nothing to do with equation, as values are in r.m.s.

 

[gar]

100912-2001 EST

robbietan:

Have you studied the various arguments throughout this discussion?

rms = root mean square

That is a true statement by definition.

= equivalent dc

Under some circumstances and with a proper definition of what are the limitations that statement can be correct, but not for all conditions.

incandescent lamp = R with no XL or XC

Not all frequencies.

frequency has nothing to do with equation, as values are in r.m.s.

RMS does not exclude frequency effects in some equations, and operating conditions.

.

 

[glene77is]

Would it be different at 50 Hz?

Sure . . . well, "could" be significantly different.
Depends on the resonant frequency of the circuit and the Q.

I designed a mechanical (analog) audio filter that was high Q, resonant at 700Hz,
down 60dB at +/- 10% of center frequency. Keep it in a box, no further use for it.
But I doubt that any of our transformer circuits are that tight;
so that would make my opinion "no" probably not significant.

 

[glene77is]

We blue collars will go chew snuff or skin squirrels or somethin.

Real-Ol-Man,
Sorry for the slight.

The world is very full of many people
with a wide range of keen Interests and developed Skills.
( I am just another one of them, an old man,
trying to get along through the rest of my life. )

These forums are a haven of good wisdom and electrical knowledge.
I hope you continue to contribute to this forum.

 

[Electric-Light]

P = 1kW

rms = root mean square = equivalent dc

On ideal resistor. Hookup a 1hp AC motor to a 48v forklift battery and come back and tell us what happens.

Read twice, post once.