Induction motors and capacitors lowers amps "consumption"

[d3adp00l]

One thing I would like to point out, and it will proly not make much sense. If you look at the name plate amperage and voltage and find the wattage of a motor, you will notice that this wattage does not coinside with the 746 stated watts. Most motors at labeled at the full load amps, which is different than the nominal load amps, which is different than the no load amps.

In other words a 1hp motor should draw 746/(its percent efficiency) at its rated output of 1hp.

Most motors are around 70% eff, so 746/.7=1065 watts actual draw. But that is with 1hp worth of load.

With no load it will draw very little wattage, and with a locked rotor (infinite load) it will draw much more wattage.

Also pay attention to the P.F. rating on the motor (power factor). A motor with a PF of .69 will "appear" to draw more amperage when using a clamp style amp meter. This is because the amp meter can not correct the power factor, and when caps are placed in the load it corrects the power factor and makes the amp meter correct again (if the right caps are placed). If too much capacitance is added into the system it will push the power factor off again but in the capacitance direction instead of the inductance direction.

There are clamp type watt meters that measure the wattage, amerage, power factor, and everything else. They use a clamp along with some clip leads that attach to the wiring of the motor. If you are going to be doing this kind of testing this is the type of meter you need. You also need to understand the amp draw at different loads.

An electric motor with no load is like a gas engine at idle, sure its turning 800rpm, but that power output is much different than it the engine was turning 800 rpm while moving a 3000lbs car.

[nueview]

so have been listening to the thread and would like to know how much capacitance you would use to correct for this power factor.

also i have never seen an ac induction motor of 1 hp idle as you say with less than 5 amp draw these windings do not resonate as do transformers to form a load so define load.

[Kyoat]

One thing I would like to point out, and it will proly not make much sense. If you look at the name plate amperage and voltage and find the wattage of a motor, you will notice that this wattage does not coinside with the 746 stated watts. Most motors at labeled at the full load amps, which is different than the nominal load amps, which is different than the no load amps.

In other words a 1hp motor should draw 746/(its percent efficiency) at its rated output of 1hp.

Most motors are around 70% eff, so 746/.7=1065 watts actual draw. But that is with 1hp worth of load.

With no load it will draw very little wattage, and with a locked rotor (infinite load) it will draw much more wattage.

Also pay attention to the P.F. rating on the motor (power factor). A motor with a PF of .69 will "appear" to draw more amperage when using a clamp style amp meter. This is because the amp meter can not correct the power factor, and when caps are placed in the load it corrects the power factor and makes the amp meter correct again (if the right caps are placed). If too much capacitance is added into the system it will push the power factor off again but in the capacitance direction instead of the inductance direction.

There are clamp type watt meters that measure the wattage, amerage, power factor, and everything else. They use a clamp along with some clip leads that attach to the wiring of the motor. If you are going to be doing this kind of testing this is the type of meter you need. You also need to understand the amp draw at different loads.

An electric motor with no load is like a gas engine at idle, sure its turning 800rpm, but that power output is much different than it the engine was turning 800 rpm while moving a 3000lbs car.

Thank you for you input.
I believe we understand the difference between no-load amps and that of a loaded motor amps.
maybe not,

But what I do know is that our 1 HP motor under a "full load" of a 60 Lb flywheel drew 9.58 amps which would translate to about 1150 watts.

But that same motor and flywheel with matched capacitance came to full RPM twice as fast which to me would indicate, with modest consideration, twice the Torque.  Same RPM's since that is based upon Hz.  And while under this same load drew only 1.86 amps.   Which is far below the normal no-load amps, and 80% less than fully loaded with out capacitance.

Since Horsepower has to do with 1) Torque 2) RPM 3) diameter(radius) I think it would be safe to assume that with the same RPM's BUT twice the Torque (start to full RPM's) than one could safely assume an increase of "Potential" horsepower.

Not only was this motor twice as fast under a full load from start to full RPM's but we also documented that it operates at extended period of time at a lower temperature as well.  Now it's my assumption that with a inefficient Induction type motor, that most of the "heat" generated comes mostly from the fields fighting them self, and the remainder from frictional losses.

We have a magnetic heater, no wiring, no current, no fuel what so ever.  And yet when rotated creates so much heat that it turns blue-hot!

So my question to you is this, with the above results as described, what would your assumption be?
We don't have any real high priced testers other than the Kill-a-watt meters, Clamp amp testers,  oscilloscope's, and so on.  Even if ...... the amps were wrong ...... if you had twice the Torque or horsepower for the same watt "consumption" I do believe this would be a huge step forward.

Thank you for your input,  Kyoat

[hoptoad]

.... if you had twice the Torque or horsepower for the same watt "consumption" I do believe this would be a huge step forward.

Without a doubt!
Cheers

[d3adp00l]

Twice the torque, would also indicate more HP.

The simple version is this, if you are making more usable power with less electrical power, yes that is a good thing. But proving it is a more important thing.

The killawatt meter will probably suffice, between that a volt meter, and a clamp amp meter you can find true amps, reactive amps, percent power factor, etc. It is just easier to do with a power factor meter since it does all that in one unit.

Plug you motor into the killawatt meter, write down that reading, write down the reading from the volt meter, and amp meter. Then compare the voltsXamps and what the killawatt meter says. If they say the same thing, then the killawatt meter is not a true watt meter, if there is a substancial difference between them (around Killawatt/(ampXvolts)=.70) then it should be accuarate enough. True watts/apparent watt = power factor. apparent watts= true watts+reactive watts.

The point of what I am saying is not to disagree with anyone, but simply to point out some of the properties involved with inductive loads and some of the common misconceptions.

You could be over correcting the capacitive balance and singing the reactive amperage from inductive to capacitive.

There is a simple way to do all of this, couple the motor to a generator (motor) turn the motor on, and have a load attached to the generator (500watt halogen light works well its a pure resistive load, and stays constant), record all of the metered data for both the motor and the generator loads. Make your changes (capacitors) and then do the same.

If the motor draws less, but maintains the light voltage and amps, then you can prove your point to almost anyone.

a motor with caps will run cooler, and yes its because the potential created when the field collapses has a capacitor to go into instead of back into the line voltage.

There are formulas on how to calc the capacitance needed for a given motor inductance, but most motors don't list the inductance and so then you need to have a meter for it, or be able to do the reactive amperage to capacitance calcs, all of it is on the net if you do a search you can find it. If you really really really need me to explain it I can go dig out my notes from when I was studying power factor.