Induction motors and capacitors lowers amps "consumption"

[hoptoad]

@hoptoad
a watt meter reading might be very instructive. if i understand the cct he has a cap in parrallell with the coils. this dose not change the voltage on the coil. current in a cap leads , current in a coil lags the voltage. in aparalell cct the two cancel out leaving the resistive current(inphase) and any reactive current
that is in excess of its opposite phase.  Ic IL and Ir are added as vectors, check out a basic ac eletricity book. the net effect here is to correct the power facter to the source. something that has been common practice in industry for a long time but not OU.

Yes, no argument there on all points.

However, there was no reference to actual power consumption or current phase angle, only the supply current consumption.
I fully understand the Z impedance relationship to resistance (R), and inductive and capacitive reactance (XL and XC), and the phase angle (and subsequent power factor) created between voltage and current in an inductor at a given frequency.

But a decrease in apparent supply current, irrespective of its phase angle to voltage is interesting from a consumers point of view, because those happy little spinning discs in the meters that are used to charge us for our electricity consumption (if you've still got an old meter), rotate at a speed which is directly proportional to the supply current, and are not influenced by any phase angle between the voltage and current in a consuming device.

You may or may not be using less actual power, but you could be paying less for it than you need to!

Cheers.

[spinner]

@hoptoad
a watt meter reading might be very instructive. if i understand the cct he has a cap in parrallell with the coils. this dose not change the voltage on the coil. current in a cap leads , current in a coil lags the voltage. in aparalell cct the two cancel out leaving the resistive current(inphase) and any reactive current
that is in excess of its opposite phase.  Ic IL and Ir are added as vectors, check out a basic ac eletricity book. the net effect here is to correct the power facter to the source. something that has been common practice in industry for a long time but not OU.

No OU. Absolutely. But, possibly a real, practically achievable and legal opportunity for "reduced" el. energy consumption  (and consequtive savings).

Yes, a current leads voltage in a capacitive load, and vice-versa with an inductive load. A reactive energy compensation does the corrections. In reality, much of the el. loads we use deviate for a pure Ohmic form.. It's all about vectors and trigonometry. A phase shift between Voltage and Current, or a "co sinus phi" between both phases...

A long time understood, well known "power factor principle", in theory (and practice).



I'll ask you again, what is the difference between an industrial and individual el. energy consumption? Or, el. energy metering?

Maybe I misunderstood you in previous threads, but it seems you are claiming that the PFC principles are good for the industry, but not for the small consumers?
Thanks for answering.

[fritznien]

No OU. Absolutely. But, possibly a real, practically achievable and legal opportunity for "reduced" el. energy consumption  (and consequtive savings).

Yes, a current leads voltage in a capacitive load, and vice-versa with an inductive load. A reactive energy compensation does the corrections. In reality, much of the el. loads we use deviate for a pure Ohmic form.. It's all about vectors and trigonometry. A phase shift between Voltage and Current, or a "co sinus phi" between both phases...

A long time understood, well known "power factor principle", in theory (and practice).



I'll ask you again, what is the difference between an industrial and individual el. energy consumption? Or, el. energy metering?

Maybe I misunderstood you in previous threads, but it seems you are claiming that the PFC principles are good for the industry, but not for the small consumers?
Thanks for answering.

this is exactly what i am saying spinner, industry (large users) are billed not just for the kwhrs they use but also the peak use and for powerr facter. as for the old watt hour meter for your house, it is accurate and dose not measure out of phase current. if i thought it did i would purchase a good meter of my own
document the difference and sue their ass off for fraud! my teacher in this was an industrial electrician who had worked for stelco steel. lots of big motors and PFC there.

[Kyoat]

First off I'd like to thank Hoptoad for bringing an interesting question to the table.  A question about watts and the AC power factor.
One of our members has a "kill a watt" meter, and so we incorporated it into our load test.

Here is some of the test data;    (AD = amp draw) (#1P = #1 primary coil amps) (#2P = #2 Primary amps) (TP = total primary amps)
                                               (#1C = #1 primary cap amps present)  (#2C = #2 primary cap amps present)

#1 Emerson motor; No load, and no cap circuit
9.51 AD     #1P 3.60         #2P 3.50         TP 7.10    .................................................... 216 watts

#1 Emerson motor with 60# flywheel load, with no cap circuit
9.47 AD     #1P 3.55         #2P 3.56         TP 7.04    .................................................... 273 watts

#1 Emerson motor with 60# flywheel, and automotive (air conditioner) air compressor with no cap circuit
9.44 AD     #1P 3.48         #2P 3.56         TP 7.04   ....................................................  287 watts

________________________________________________________________________________________

#1 Emerson motor with 219 uf cap circuit, No load
2.08 AD     #1P 3.61         #2P 3.45         TP 7.06                                                         190 watts

#1 Emerson, 219 uf circuit, 60 lb flywheel load
2.51 AD     #1P 3.50         #2P 3.44         TP 6.94     #1C 4.73    #2C 4.41   TC 9.41        244 watts

#1 Emerson, 219 uf circuit, flywheel and air compressor load
2.61 AD     #1P 3.60        #2P 3.33         TP 6.93     #1C 4.64     #2C 4.55   TC 9.19        258 watts
________________________________________________________________________________________

#1 Emerson, No cap circuit, with flywheel and compressor
air output from compressor restricted until Emerson amp draw climbed above 10 amp draw

10.90 AD    #1P 3.99       #2P 3.94       TP 7.93  ...................................................       765 watts

same air restriction as above, and while motor was still running added 219 uf to primary coils.
6.50 AD     #1P 4.00       #2P 3.83        TP 7.83 ...................................................        720 watts

Not much of a gain (45 watts) when the power factor is added into the equation.

We were wondering if any one has tried converting the AC-in with a couple diodes to create a DC pulse to run an induction motor?
It's my understanding that they run well on a DC pulse.  But I was wondering how the PF would "see" this aspect of a circuit?
We were thinking, that you just need to "fool" the PF sensor some how in not seeing or feeling what's going on further down the line if it's even possible.  I have a feeling that "they" already have most bases covered to make sure that we "pay" thru the nose for our electricity.

___________________________________________________________________________________________________

In a separate test we got the following results: (all readings from watt meter)

#1 Emerson motor No cap circuit, no load ................... 9.69 amps ......................... at 215 watts
#1 Emerson motor, 219uf cap circuit, no load .............. 2.16 amps ......................... at 204 watts

#2 Delta motor, No caps, no load ...............................  4.09 amps ........................ at   95 watts
#2 Delta motor, 150uf cap circuit, no load .................... 4.13 amps ........................ at   96 watts

#3 Heater, No caps ...................................................  4.02 amps .......................  at 485 watts
#3 Heater, 150uf cap series-parallel circuit...................  3.50 amps .......................  at 360 watts

                       Total with no cap circuit:....................... 17.80 amps ...... Total ......... at 795 watts
                       Total with cap circuits .........................   9.79 amps .....  Total ........  at  660 watts

difference between no-cap circuit and a cap circuit:          8.01 amp drop                    135 watt drop

___________________________________________________________________________________________________

This test was run with the following:

#1 Emerson motor with 219uf cap circuit on #1Primary coil only, no load
#2 Delta motor connected to Emerson #2Primmary coil, 150uf cap circuit on delta
With just these two motors connected together: ...............7.30 amps ....................... at 382 watts

      Difference between separate verses "together"             1.01 amp increase            and 82 watt increase


#1 Emerson motor with 219uf on #1P cap circuit, no load
#2 Delta motor connected to Emerson #2 Primary coil, No cap circuit, no load
#3 Heater with 150uf series-parallel cap circuit on L1, heater connected to Delta primary coils.
With all three connected together: ..................................  7.42 amps ..................     at 672 watts

Difference between separate verses connected "together"    2.33 amp drop ...........      at   13 watt increase!!

[gyulasun]

Hi Kyoat,

Thanks for the reply and the further measurements with the kill-a-watt meter.

I think if you could afford some time to repeat the same test setup when you drive the Emerson from the mains and the it drives the Delta and the heater is connected in series with the 150uF and these two in parallel with the Delta as you desribed.  In this setup the what would the kill-a watt meter show on the input power and on the power factor?
Of course,  I know it depends on your and your friends time, no problem if you cannot do it now, maybe later...and this holds for the DC resistances of the motors.

Many thanks for all your kind efforst here showing your results.

Regards,  Gyula