Steve hit the culprite correctly with the ELI the ICE man reference.
Notice with each type of reactance, there's a difference in time when the voltage and current waves cross the zero line [or when they peak]?? That's what creates "Power Factors", since the waves are not crossing zero equally in time [AKA "Not In Phase Time"].
With something that has almost no Reactance [such a small amount of Reactance, it's less than 0.0001% of the load], it has close to no phase lag - meaning that the Voltage [E] and the Current [I] waves cross zero at the same time [in phase with each other]. These draw completely True Power only.
True power loads do not draw any VARs [Volt-Amps Reactive power], which means all the load current & Voltage for that Resistive load can be applied to the total wattage developed at the load.
In that case, ExI=P, and the P equals True Power [Wattage, or simply Watts].
Looking at this power on a Power Graph, the complete power wave is above zero line and peaks in one wave. [That's kind of the EE way of viewing it].
All this cannot be said for any REACTIVE elements and the circuits connected to them.
The term: ELI the ICE man shows which wave will lag, as to the type of Reactance involved. In the case of series elements with both types of Reactance, the one with the highest level will determine the type Reactance - also is the 2nd part of the Impedance formula.
These are abbreviations for terms:
X = Reactance [total],
XL = Inductive Reactance,
XC = Capacitive Reactance,
Z = Impedance,
R = Resistance [total],
KW and/or Wattage = True Power,
KVA and/or VA = Apparent Power,
KVAR and/or VAR = Reactive Power.
In case someone might be unfamiliar to ELI the ICE man, I'll describe it's intent:
ELI means that the voltage wave [E] will lead the current wave [I] on Inductive Reactances [L].
The Current wave will lag behind the Voltage wave, between 0.1 and 90 degrees - depending on the Power Factor at that element.
ICE means that the Current Wave [I] will lead the Voltage Wave [E] on Capacitive Reactances [C].
The Voltage wave will lag behind the Current wave, between 0.1 and 90 degrees - depending on the Power Factor at that element.
These Reactive elements draw Volt-Amperes from the AC line, in which two [2] separate types of power are contained:
1: True Power - this is the actual wattage being applied to the load element,
2: Volt-Amps Reactive - this is power that doesn't do anything as to the work [or kinetic energy] dissipated at the load is conserned. Simply, it does almost nothing usefull, but is a result of AC across something other than pure Resistance.
VARs are also termed "Scuttle / Shuttle Power", because they only flow between the power supply [transformer or generator] and the load element, but contribute nothing to the output KW at the load.
It does increase levels of Current [XL] which heats conductors, windings, and such - further aggrevating the Voltage Drops.
XC increases Voltages, so it too can result in an increased Current drawn on loads, due to the elevated E on the KW portions.
Power Factor [PF] is the relationship between the level of Apparent Power being drawn [KVA] and the level of True Power being used [KW] on a load. Levels run from 0.1% to 99.99999%
Nominal PF is 50% [this is a low power factor], whereas high PF is >95%. Corrected PF is anywhere from 70% to 90%.
The reciprocal power is the VARs.
VARs are magnetizing currents [XL], or Capacitive Charging Fields [XC], either way they do some type of charging.
Since there's all this lagging going on, the power cannot be correctly figured using ExI=P.
This will only result in Apparent Power [VA].
True Power is figured by adding the power factor to the formula:
ExIxPF=P [Volts x Amps x Power Factor = KW].
KVA / VA power waves on a power graph do not fall completely above the zero line. There's several peaks and the waves dip below zero, then rise above.
A phase angle [lag] of 90 degrees [the result of complete XL or XC only] will have equal peaks above and below the zero line. These cancel each other out, so there's no True Power being used at that element what so ever - even though there's plenty of KVA flowing.
This situation is not desirable for the complete load, as it does nothing!! It's something that a Ballast would {hopefully} have.
With phase lags less than 90 degrees, the level of power on the wave above the zero line becomes higher than below the zero line. Now there's something left over when the math is done - which results in True Power being included in the wave.
Let me know how this is and if I left something out.
Scott SET
