cfl's , poor Power Factor and your power meter

[tuppy]

With all the fuss over powerfactor correction (or lack of) with CFL
lamps and with some cfls with poor powerfactor (like 0.4) the actual
power usage can be double the stated Watt rating.
I didn't really care as my powermeter measures Kilowatts , ie its not
a VA meter but doing a little more reasearch I realise we are paying
for the poor power factor. What a scam!

Take a look at your power meter; I think it measures apparent power
thought its actually called KWH meter that is contradictory to one
another KVAH meter is apparent power while KWH is real power, if you
look upon the construction of the meter itself it acts like a simple
induction motor running both is current and in voltage, the line
current is usually the total current you use in your household, P=VA ,
this is actually the formula for apparent power in an AC circuits,
because P=VA X power factor is the formula for real power in AC
circuits and I don't see any provisions of power factor reading in the
KWH meter that makes me conclude that indeed the meter used in our
homes measures apparent power not real power. though it states KWH
meter on the nameplate.

 

[Phil Allison]

"tuppy the troll "

With all the fuss over powerfactor correction (or lack of) with CFL
lamps

** Inrush surge is a FAR bigger issue with CFLs than the distorted current
wave issue.

and with some cfls with poor powerfactor (like 0.4) the actual
power usage can be double the stated Watt rating.

** Utter BOLLOCKS !!

The stated power consumption in watts for CFLs IS the REAL power
consumption.

I didn't really care as my powermeter measures Kilowatts , ie its not
a VA meter but doing a little more reasearch I realise we are paying
for the poor power factor. What a scam!

** More BOLLOCKS.

Domestic power meters ARE watt meters.

http://en.wikipedia.org/wiki/Electricity_meter#Electromechanical_meters

Take a look at your power meter; I think it measures apparent power

** Totally false.




...... Phil

 

[Davo]

tuppy wrote:

With all the fuss over powerfactor correction (or lack of) with CFL
lamps and with some cfls with poor powerfactor (like 0.4) the actual
power usage can be double the stated Watt rating.
I didn't really care as my powermeter measures Kilowatts , ie its not
a VA meter but doing a little more reasearch I realise we are paying
for the poor power factor. What a scam!

Take a look at your power meter; I think it measures apparent power
thought its actually called KWH meter that is contradictory to one
another KVAH meter is apparent power while KWH is real power, if you
look upon the construction of the meter itself it acts like a simple
induction motor running both is current and in voltage, the line
current is usually the total current you use in your household, P=VA ,
this is actually the formula for apparent power in an AC circuits,
because P=VA X power factor is the formula for real power in AC
circuits and I don't see any provisions of power factor reading in the
KWH meter that makes me conclude that indeed the meter used in our
homes measures apparent power not real power. though it states KWH
meter on the nameplate.

From Wiki

Electromechanical meters
The most common type of electricity meter is the Thomson or
electromechanical induction watt-hour meter, invented by Elihu Thomson
in 1888.
The electromechanical induction meter operates by counting the
evolutions of an aluminium disc which is made to rotate at a speed
proportional to the power. The number of revolutions is thus
proportional to the energy usage. It consumes a small amount of power,
typically around 2 watts.
The metallic disc is acted upon by two coils. One coil is connected in
such a way that it produces a magnetic flux in proportion to the voltage
and the other produces a magnetic flux in proportion to the current. The
field of the voltage coil is delayed by 90 degrees using a lag coil.
[1]This produces eddy currents in the disc and the effect is such that a
force is exerted on the disc in proportion to the product of the
instantaneous current and voltage. A permanent magnet exerts an opposing
force proportional to the speed of rotation of the disc - this acts as a
brake which causes the disc to stop spinning when power stops being
drawn rather than allowing it to spin faster and faster. This causes the
disc to rotate at a speed proportional to the power being used.

From me

So the meter has two coils, one for voltage and one for current.
Try putting some big inductors or capacitors on your circuit as a load,
what does the power meter do?

 

[Eeyore]

tuppy wrote:

With all the fuss over powerfactor correction (or lack of) with CFL
lamps and with some cfls with poor powerfactor (like 0.4) the actual
power usage can be double the stated Watt rating.

Fundamental misunderstanding of physics. The VA usage (apparent power) may
be higher but NOT the actual power.

Graham

 

[Franc Zabkar]

On Thu, 9 Apr 2009 17:27:30 -0700 (PDT), tuppy <george@joho.com> put
finger to keyboard and composed:

Take a look at your power meter; I think it measures apparent power
thought its actually called KWH meter that is contradictory to one
another KVAH meter is apparent power while KWH is real power, if you
look upon the construction of the meter itself it acts like a simple
induction motor running both is current and in voltage, the line
current is usually the total current you use in your household, P=VA ,
this is actually the formula for apparent power in an AC circuits,
because P=VA X power factor is the formula for real power in AC
circuits and I don't see any provisions of power factor reading in the
KWH meter that makes me conclude that indeed the meter used in our
homes measures apparent power not real power. though it states KWH
meter on the nameplate.

From Energy Australia:

===================================================================
.... most residential classification customers are metered by a
spinning disc meter, or a basic electronic meter which does not have
enough "smarts" in the meter device to enable billing to be carried
out at a KVA pricing.

Currently small customers are billed on KWh pricing, and KVA Demand
pricing usually relates to large commercial and industrial
installations where poor power factor may impact upon the EA network
....
===================================================================

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[tuppy]

thanks Franc,

looks like I dont have to worry about paying for powerfactor.

thanks again for good answer.

Take a look at your power meter; I think it measures apparent power
thought its actually called KWH meter that is contradictory to one
another KVAH meter is apparent power while KWH is real power, if you
look upon the construction of the meter itself it acts like a simple
induction motor running both is current and in voltage, the line
current is usually the total current you use in your household, P=VA ,
this is actually the formula for apparent power in an AC circuits,
because P=VA X power factor is the formula for real power in AC
circuits and I don't see any provisions of power factor reading in the
KWH meter that makes me conclude that indeed the meter used in our
homes measures apparent power not real power. though it states KWH
meter on the nameplate.

From Energy Australia:

==================================================================> ... most residential classification customers are metered by a
spinning disc meter, or a basic electronic meter which does not have
enough "smarts" in the meter device to enable billing to be carried
out at a KVA  pricing.

Currently  small customers are billed on KWh pricing, and KVA Demand
pricing usually relates to large commercial and industrial
installations where poor power factor may impact upon the EA network
...
==================================================================
- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Pete]

... most residential classification customers are metered by a
spinning disc meter, or a basic electronic meter which does not have
enough "smarts" in the meter device to enable billing to be carried
out at a KVA pricing.

That part is phrased interestingly - does it mean that if we get
"non-basic" electronic meters, that they'll start KVA pricing?

I think I remember hearing that we're all going to get new electronic
meters in Victoria in the medium term. I wonder what type of meters?

Peter