Electrical Q's How do they Measure Kilowatts

[JimR]

Is it Real Power or Watt-hour Power
Please if anybody knows this Q's can you help me

Thank You
Jim

[Ron]

Units for real power is in watts and units for apparent power in voltamps.
The formula to go from one to the other is a multiplier of a unit called power factor.

Watts=Voltamps x power factor

Power factor is related to the phase shift between voltage and current.

The utility company charges you in units of kWH, which is 1000 Watts over a period of one hour.

[suemarkp]

Not sure of your question. Do you mean watt-hour power versus amp-hour (VA) power? If so, a watt meter measures true watts, not VA. This would be an easy way to determine your power factor -- compare the watt meter with the amps being drawn (or a VA meter if such things exist).

[Homer]

Is it Real Power or Watt-hour Power
Please if anybody knows this Q's can you help me

Thank You
Jim
The letters used for the power triangle are

P = Real Power (Watts)
S = Apparent Power (VA's)
Q = Reactive Power (VAR's); where VAR is VoltAmps Reactive

The main formulas are S = SquareRoot(P^2 + Q^2)
and Power Factor = (P / S)

As far as a description goes, Reactive Power (Q) in the Power Triangle (P, S & Q) corresponds to the Reactance (X) in the Impedance Triangle (R, Z & X).

Homer

[Wgoodrich]

Gosh I sure hope Jim is well versed in the art of electricity. He would have to be to understand what you guys are saying TECHNICALLY.

Now can anyone reply in plain language for a normal guy or gal can understand? That I suspect is what he is looking for.

Curious

Wg

[Homer]

Gosh I sure hope Jim is well versed in the art of electricity. He would have to be to understand what you guys are saying TECHNICALLY.
In defense of the replies, I don't think any of us were really sure what was being asked. I thought maybe he was referring to the Q's in the power triangle but maybe that was simply a shortform for the word question?

If the question is simply how do they measure Kilowatts compared to Kilowatt-Hours, then I will attempt to give an answer.

Real power is measured in Watts (W) or Kilowatts (kW) where 1 kW = 1000 Watts. Energy consumption is measured in Kilowatt-Hours.

In terms of physics, power is a rate of energy usage, not a total of energy used. Compared to a mileage example, if you have a rate of travel of 50 MPH (speedometer) you need a time factor over which to total the distance travelled (odometer). So kW is like the MPH and the kW-Hour is like the Mile.

Distance = Rate of Speed x Time
Miles = MPH x Hours

Energy Used = Rate of Energy Usage (or Power) x Time
KiloWattHours = kW x Hours

Now, KilowattHours are measured with the KilowattHour meter that you are familiar with in your home.

The real power in a circuit (Watts) is measured with a WattMeter.

The apparent power in a circuit (VoltAmps) is measured with both a VoltMeter (voltage in V) and an Ammeter (current in A) and calculated by multiplying the two numbers together.

The WattMeter is like a speedometer measuring your rate of energy usage and the KilowattHourMeter is like an odometer measuring your total energy consumed and billed by your utility.

Maybe this reply will hit the mark a little better. :D

Homer

[Ron]

It was not my intent to confuse, but the difference between VA and W is technical. No getting around that :)

[Wgoodrich]

Ya got to crawl before you walk. You have no idea how many times I have tried to answer this type question in laymen's terms and that was to 10 year experienced home wiring electricians. Many know how to wire and make it work even know how to meet minimum safety standards pretty well but a huge percentage of electricians often flunk an in depth high level general knowledge / theory test.

I think Homer did pretty well in his attempt to speak in human language for those just trying to start understanding that subject. Ron is correct it is a deep technical subject. Problem is we need to start somewhere and simple language needs to be used to explain a highly technical subject. Kind of like throwing a person in a river and say SWIM. Not easy to explain. Just wanted to see someone else try to explain in normal language to see if I could pick up a trick or two in my attempts to explain in the future.

Thanks

Wg

[JimR]

This is JIMR Thank you Ron and Suemarkup Real Power was the Answer i found it in my Code Book NEC 2002 i am going for My Licenses on April 8th so that's one of the Q's
Thank you Everyone

Jim

I have one more Q's what's the Isolation call Eddy's Isolation? i have to find it in the Code but if someone can help me that would be great

[JimR]

i mean to say (Insolation) i was typing fast sorry guys and laddy's if there are any laddy's

[JimR]

On an AC unit the Equipment gounding conductor must be run back to the

A. Equipment Disconnect

B. Service Disconnect

C. Building

D. Gounding Electrode

[mdshunk]

Air conditioner ECG's are typically made of 7 1/2 AWG jacketed preframulated amulite and run to the sinusoidal dingle bar of the turbo encabulator panel. What this has with measuring kilowatt/hours I don't really know.

[Wgoodrich]

MDshunk, I think JimR is studying practice questions and throwing a few out for us to help sort out what he does not understand yet.

JimR, no matter the type insulation Edy currents will emit as an electomagnetic current flow of minor voltage along the outside of the insulated wire. Edy Currents run along a conductor whether insulated or not and runs as a dispursment into the air, normally unharmed. There are some concern about extreme high voltage transmission towers emitting these currents EMF that may be harming health in vicinity of those high voltage lines. If you wish to see these edy currents take an electronic voltage tester often called an idiot tester that measures a/c and d/c voltage from 12 volts to 440 volts. Find a neon sign low to the floor. Walk up to that sign pointing the positive prong on that tester toward that sign. You should see the lights start lighting up about 8' away and get brighter as you approach that neon sign.


YOU SAID;

On an AC unit the Equipment gounding conductor must be run back to the

A. Equipment Disconnect

Yes if the disconnect is different than the main service panel. If the a/c unit is in sight of that main service disconnect then an equipment disconnect would not be required. Then the answer gets a bit cloudy. The equipment disconnect must be fed by a feeder that has a grounding conductor connecting that equipment disconnect to the service disconnect.


B. Service Disconnect

Yes if the service disconnect serves as the equipment disconnect. Otherwise the equipment disconnect would be required to extend that a/c equpment grounding conductor through that equipment disconnect to the service disconnect. Then again the grounding electrode conductor is also required to extend that a/c equipment grounding through the equpment disconnect to the service disconnect then through the service disconnect to the grounding electrode by way of the grounding electrode conductor.

C. Building

Building would not apply unless this building is metal. Then yes this also would be in contact with the equipment grounding system. Then again If this is a metal building with red iron and if this building is being used as ground then that red iron building may be connected by the a/c unit without further passing the equipment grounidng conductor between the sub panel [equipment disconnect] and the service equipment. What I am saying is the grounding conductor may be the metal red iron of a steel structural buildng in place of an equipment grounding conductor running back to the service equipment. The metal red iron may be used as an equipment grounding conductor for the feeder serving that equipment disconnect.

D. Gounding Electrode

This is the place where all equipment grounding must end up in.

Be aware though the equipment grounding conductor in a branch circuit or feeder if installed must run with the feeder or branch circuit in the same path.

Only thing throwing an if in the picture is the rule allowing red iron of a grounded industrical building being allowed to be used as a grounding path.

Answer most in the simple form would be the equipment disconnect. A

Problems occur the more you know about electrical Codes. When you get to the higher level of knowledge everything in a test can become gray area if the question is not worded exactly right with no other alternative equally strond answer match.

Hope this helps

Wg

[Unregistered]

help needed here ! does faradays cage need grounding or not in order to stop radio frequencies. If the answer is yes ,then what about eddys current that flows through cage and repulces RF. I will appriciate an early answar.

Thanks,
Monty.

[mdshunk]

help needed here ! does faradays cage need grounding or not in order to stop radio frequencies. If the answer is yes ,then what about eddys current that flows through cage and repulces RF. I will appriciate an early answar.

Thanks,
Monty.

Yes, the more the better. This will eliminate non-linear replaneration exposures, as well as allow for re-emerent RF capitulation.