Electricity measurments - toying around with a meter... ;-)

[Pszemol]

Just in case somebody is curious how much electricity
his 96 power compacts really consume, read the following...

I used a meter from RadioShack called Kill-A-Watt today.
It shows volts, amperes, frequency, watts, power factor etc.

I have measured CustomSealife 36" 96W power compacts
on 110W ballast I got from AH Supply (www.ahsupply.com).
Here is what I measured: 124V/59.9Hz, 1.06A, pf=0.91, 120W.
So in my case, ballast+bulb combination consumes 120W of power.
Assuming the bulb is driven at nominal 96W of power the
ballast works on the 80% level of efficiency - not bad.

BTW - this ballast is pretty good in terms of power factor.
I have measured "60W replacement" 13W fluorescent lamp from
Menards and it measured power factor 0.59, almost as bad as
my magnetic water pump - QuietOne 3000 which measured 0.57 :-)))

[Dr Drudge]

"Pszemol" > wrote in message >...
> Just in case somebody is curious how much electricity
> his 96 power compacts really consume, read the following...
>
> I used a meter from RadioShack called Kill-A-Watt today.
> It shows volts, amperes, frequency, watts, power factor etc.
>
> I have measured CustomSealife 36" 96W power compacts
> on 110W ballast I got from AH Supply (www.ahsupply.com).
> Here is what I measured: 124V/59.9Hz, 1.06A, pf=0.91, 120W.
> So in my case, ballast+bulb combination consumes 120W of power.
> Assuming the bulb is driven at nominal 96W of power the
> ballast works on the 80% level of efficiency - not bad.
>
> BTW - this ballast is pretty good in terms of power factor.
> I have measured "60W replacement" 13W fluorescent lamp from
> Menards and it measured power factor 0.59, almost as bad as
> my magnetic water pump - QuietOne 3000 which measured 0.57 :-)))

Why do you characterize 0.57 as a 'bad' power factor? The mag pump is
by by definition an inductive load as is the transformer in the fl
lamp you mentioned above.
The power company should be more concerned with this that than you.

[Pszemol]

"Dr Drudge" > wrote in message om...
> > BTW - this ballast is pretty good in terms of power factor.
> > I have measured "60W replacement" 13W fluorescent lamp from
> > Menards and it measured power factor 0.59, almost as bad as
> > my magnetic water pump - QuietOne 3000 which measured 0.57 :-)))
>
> Why do you characterize 0.57 as a 'bad' power factor? The mag pump is
> by by definition an inductive load as is the transformer in the fl
> lamp you mentioned above.

I did not say pump power factor is bad. It cannot be to much better.
But in case of electronic fluorescent ballast it is bad, because it
has it not corrected to be close to 1 like the one from AHsupply.
I was just comparing these two fluorescent ballasts in terms
of power factor.

> The power company should be more concerned with this that than you.

Not only power company. The place I live is not designed to host
so many electrical devices and the fuse is too small. In the summer,
with air drawing too much current the breaker often trips...
I am interested in power factor in a similar way power company is:
power factor closer to 1 means less current flowing through my
wires and my fuse breakers. I do not want my breaker to trip when
I am not home and have the fish tank going hours without power,
so it makes a difference when my 240W lights are running with
power factor close to 1 and draw only 2A of current or with other ballast
with worse power factor and drawing 3 or 4 amps and trip the breaker...

[B McDonald]

"Pszemol" > wrote in message
...
>
> Not only power company. The place I live is not designed to host
> so many electrical devices and the fuse is too small. In the summer,
> with air drawing too much current the breaker often trips...
> I am interested in power factor in a similar way power company is:
> power factor closer to 1 means less current flowing through my
> wires and my fuse breakers. I do not want my breaker to trip when
> I am not home and have the fish tank going hours without power,
> so it makes a difference when my 240W lights are running with
> power factor close to 1 and draw only 2A of current or with other
ballast
> with worse power factor and drawing 3 or 4 amps and trip the
breaker...

OK. If I remember my circuit theory correctly, the PF has no impact on
the *real* current draw of the device. If the device is rated for 240W
it will draw 240W regardless if it has unity PF or a PF of 0.5.

All a non unity PF means is that the voltage & current are out of
phase - in the case of an inductive load the voltage leads the current
since inductors resist instantaneous changes in current. It should have
no affect on the tripping of your breaker since these breakers trip
magnetically. Now with that said, in the summer your total draw is
probably alot higher so when a motor kicks on if you have other loads on
that circuit you may trip it out because of your starting current which
is typically 4-5 times your normal load running current.

I think Dr Druge was correct, only the power company should be concerned
unless they are charging you for having a non unity PF ( which they do
for large industrial customers)

[Dr. Drudge]

"B McDonald" > wrote in message
...
>
> "Pszemol" > wrote in message
> ...
> >
> > Not only power company. The place I live is not designed to host
> > so many electrical devices and the fuse is too small. In the summer,
> > with air drawing too much current the breaker often trips...
> > I am interested in power factor in a similar way power company is:
> > power factor closer to 1 means less current flowing through my
> > wires and my fuse breakers. I do not want my breaker to trip when
> > I am not home and have the fish tank going hours without power,
> > so it makes a difference when my 240W lights are running with
> > power factor close to 1 and draw only 2A of current or with other
> ballast
> > with worse power factor and drawing 3 or 4 amps and trip the
> breaker...
>
> OK. If I remember my circuit theory correctly, the PF has no impact on
> the *real* current draw of the device. If the device is rated for 240W
> it will draw 240W regardless if it has unity PF or a PF of 0.5.
>
> All a non unity PF means is that the voltage & current are out of
> phase - in the case of an inductive load the voltage leads the current
> since inductors resist instantaneous changes in current. It should have
> no affect on the tripping of your breaker since these breakers trip
> magnetically. Now with that said, in the summer your total draw is
> probably alot higher so when a motor kicks on if you have other loads on
> that circuit you may trip it out because of your starting current which
> is typically 4-5 times your normal load running current.
>
> I think Dr Druge was correct, only the power company should be concerned
> unless they are charging you for having a non unity PF ( which they do
> for large industrial customers)
>
>
Well Pszemol has a point- if two devices rated each at 100W REAL POWER have
a diffferent power factor (PF), the one with the higher PF will draw less
current. Now, I'm not sure if that is what his idea was , but in theory
there may be a difference.
I'm not even sure how the power consumption of a pump or ballast or lamp is
rated- Real Power, Apparent Power, or VA. Reminds me of $29 stereo speakers
rated at 150W capacity- read the fine print.

Feels good to talk "engineering" for a change.

[Pszemol]

"B McDonald" > wrote in message ...
> OK. If I remember my circuit theory correctly, the PF has no impact on
> the *real* current draw of the device. If the device is rated for 240W
> it will draw 240W regardless if it has unity PF or a PF of 0.5.

You are mixing terms above...
Real power consumed by the device is given with an equation:

P = U * I * pf

where:
P - real power consumed, in Watts
U - voltage on the device, in Volts
I - current flowing in the wires, in Amperes
pf - power factor (always < 1 for non-resistive loads)

If you have two fluorescent lamps with same watt rating, one having
electronic ballast with pf>0.91 and the other with magnetic one
and pf<0.50 thant even if P will be equal in both the one with
pf 0.5 will draw almost twice the current than the one with pf 0.9
Does it make sense for you now, when you see the equation?

> All a non unity PF means is that the voltage & current are out of
> phase - in the case of an inductive load the voltage leads the
> current since inductors resist instantaneous changes in current.

Power factor can be understand as a cosinus of phase shift
in such simple inductors/capacitance mixtures... But it is
not such simple when you measure electronics device with
active, non-linear components like diodes, transistors etc.
When you look at the current with your scope when you use
electronics device it will most likely not be even similar
to sinus wave... It is hardly any sense talking about phase
shift between voltage and current when you have electonics
as a load. And when the current is not a sine wave, it means
it has a lot of harmonics affecting power factor regardless
of the phase shift.

> It should have no affect on the tripping of your breaker
> since these breakers trip magnetically.

It does it matter how they trip - thermally or magnetically!
They are sensitive on RMS current flowing through the wire.
With low power factor current flowing in the wire is bigger.
With bigger current you will have bigger loses on the power
lost to heating wire or voltage drop. That is the reason
power company cares about power factor of devices connected
to the grid, and this is the reason for correcting the power
factor in the first place: you do not want huge cureent
flowing from and to the grid not doing any work, because
the customer does not pay for current - he pays for Watts
used, so low power factor at the load is the power company lost.

> Now with that said, in the summer your total draw is
> probably alot higher so when a motor kicks on if you have other loads on
> that circuit you may trip it out because of your starting current which
> is typically 4-5 times your normal load running current.

Lets say this way: assuming what you said is true, I will
still like all other electric devices to take the smallest currents
because ALL devices add to the total current the breaker feels.
When the total sum of all current go above the trigger value
the breaker trips.

> I think Dr Druge was correct, only the power company should be concerned
> unless they are charging you for having a non unity PF ( which they do
> for large industrial customers)

I have explained above why it is interest of mine as well.
Think about it... If the "current draw" was equal regardless
of power factor (like you were trying to say) why would they
care? Why would the pay extra money for correcting power factor?
The answer is simple: because low power factor causes huge
electrics currents flowing aimlessly and causing electric loses
on the transmission lines (grid) due to the heat dissipation...

[Pszemol]

"Dr. Drudge" > wrote in message et...
> Well Pszemol has a point- if two devices rated each at 100W REAL POWER have
> a diffferent power factor (PF), the one with the higher PF will draw less
> current. Now, I'm not sure if that is what his idea was , but in theory
> there may be a difference.

Yes, this was my idea exactly.

That is why I graded the second electronics ballast
with pf=0.57 "worse" than the one with pf=0.91 :-)

Also, I was interested in how much of electricity is lost in the
ballast alone - it was hot to touch, so I wanted to check it out.

> I'm not even sure how the power consumption of a pump or ballast or lamp is
> rated- Real Power, Apparent Power, or VA.

Small pumps (powerheads) have usually maximum real power consumed stated.
Bigger pumps, with separate electric motors, are usually rated in "amps"
so they state what is the maximum current the motor draws. This way it is
easier to control motor malfunction/overheating with a simple AC ampmeter.
Of course it is not the current*voltage which gives you consumed power...
Real power consumed by the motor is easy to calculate IF the manufacturer
stated power factor on the label as well. If not, you only guessing :-)
Multiplying voltage and current amps gives you VA (volt amperes).

Fluorescent ballasts (electronic or magnetic) are rated in watts of bulbs
they are designed to work with. This has nothing to do with watts the
ballast is loosing on it own. It is usually much less, as it was visible
on my measurement example: ballast rated 110W installed with 96W bulb
created a lamp device with total power dissipation of 120W. So the
ballast alone dissipated 120-96 = 24W mainly in the form of heat...
Fluorescent bulbs are rated in watts they consume generating light+heat.
Efficiency of fluorescent bulb is average 40% so about 60% is lost as heat.

> Feels good to talk "engineering" for a change.

Well... is it always good to know how stuff really works :-)

[Pszemol]

"Pszemol" > wrote in message ...
> Power factor can be understand as a cosinus of phase shift
[...]
> to sinus wave...

Please, excuse my English in statemets above...
I was talking about "sine" and "cosine", of course.
Somehow latin terms are stuck in my head for trigonometry.

BTW - I have also measured other fish tank equipment in my house
yesterday - yes, I was really bored and playing with this toy :-)

Two small magnetic ballast fixtures over my freshwater tanks:

the one over 5 galon tank, GE AQUA RAYS with F14T8-AR-FS 14W bulb:
voltage 124V/59.9Hz, current 0.33A, pf=0.45, total 18W/41VA.
the one over 10 galon tank, ZOO-MED DAYLIGHT with F15T8/5500K bulb:
voltage 124V/59.9Hz, current 0.33A, pf=0.50, total 20W/41VA.

As you can see, fixtures with magnetic ballasts are really bad
in terms of power factor and with amount of current they draw.

I have measured two power filters by AquaClear also:

AquaClear Mini: pf 0.46 when impeller stuck, pf 0.50 when turning.
AquaClear 150: same power factor, 0.12A when stuck, 0.08A turning.

[B McDonald]

Yes, you are correct I was confusing real power and current drawn. The
circuit protection devices must be rated for the total VA on the
circuit. My post last night bugged me all day and I was hoping to
correct myself before you replied.

I did start my post with "if I remember correctly...." which of course I
didnt.

[Dr Drudge]

"Pszemol" > wrote in message >...
> "Pszemol" > wrote in message ...
> > Power factor can be understand as a cosinus of phase shift
> [...]
> > to sinus wave...
>
> Please, excuse my English in statemets above...
> I was talking about "sine" and "cosine", of course.
> Somehow latin terms are stuck in my head for trigonometry.
>
> BTW - I have also measured other fish tank equipment in my house
> yesterday - yes, I was really bored and playing with this toy :-)
>
> Two small magnetic ballast fixtures over my freshwater tanks:
>
> the one over 5 galon tank, GE AQUA RAYS with F14T8-AR-FS 14W bulb:
> voltage 124V/59.9Hz, current 0.33A, pf=0.45, total 18W/41VA.
> the one over 10 galon tank, ZOO-MED DAYLIGHT with F15T8/5500K bulb:
> voltage 124V/59.9Hz, current 0.33A, pf=0.50, total 20W/41VA.
>
> As you can see, fixtures with magnetic ballasts are really bad
> in terms of power factor and with amount of current they draw.
>
> I have measured two power filters by AquaClear also:
>
> AquaClear Mini: pf 0.46 when impeller stuck, pf 0.50 when turning.
> AquaClear 150: same power factor, 0.12A when stuck, 0.08A turning.

Nice toy you got there...

[OT]: I remember reading an article from some conservationists about
the importance of reducing your home's "stand-by" energy usage. If you
add up all the energy used by all your appliances that are supposed to
be "off" you can have significant waste. Think about all the
microwaves,tvs,vcrs,stereos, etc. that have "always on" circuitry (the
clock for example)...

[Dr Drudge]

"B McDonald" > wrote in message >...
> Yes, you are correct I was confusing real power and current drawn. The
> circuit protection devices must be rated for the total VA on the
> circuit. My post last night bugged me all day and I was hoping to
> correct myself before you replied.
>
> I did start my post with "if I remember correctly...." which of course I
> didnt.

I am not an electrician (but I do have an "unused" EE degree). Having
said that:

"Total VA" is not important to the fuse/breaker as far as the trip
load. A 20A fuse/breaker is designed to trip at 20A- you can use it in
a 50v circuit as well as a 125v circuit.

VA is the rms (or you could specify peak or max) Voltage times (*) the
rms Current (A), which is removes our friend Power Factor from the
equation. So, for example, a 120v motor drawing 2A would be 240 VA.

Voltage ratings on fuses and breakers specify the safe max potential
difference (voltage) that can be applied. The higher the voltage, the
more risk you run of arcing between the contacts- that is one of the
factors in a voltage rating.

[Pszemol]

"Dr Drudge" > wrote in message om...
> Nice toy you got there...
>
> [OT]: I remember reading an article from some conservationists about
> the importance of reducing your home's "stand-by" energy usage. If you
> add up all the energy used by all your appliances that are supposed to
> be "off" you can have significant waste. Think about all the
> microwaves,tvs,vcrs,stereos, etc. that have "always on" circuitry (the
> clock for example)...

Yes, if you are heavy populated with this kind of equipment it
could be something around 100W burning 24/7, but usually
you want to pay for the convenience of "always on" feature...
This cost is not so huge compared to your other spendings ;-)