LEDinside released a new Knowledge Base article to understand the power factor
of the LED lamps]
LED, fluorescent or incandescent lamps with, we have to
understand one of the important parameters - power factor (PFC), Let's check
what is the power factor 1, the power factor power factor characterizes the
ability of the lamp output active power. Power is a measure of the energy
transfer rate in the DC circuit voltage V and current A and the product. In the
exchange system is far more complex: that part of the AC current in the loop
where the load does not transmit power, it is called reactance current or
harmonic current, it makes the current multiplication in the power (voltage Volt
Amps) is greater than the actual power. Leads to the power factor, apparent
power and actual power ranging from power factor equal to the actual ratio of
the power and apparent power. Exchange systems, the actual power is equal to the
apparent power times the power factor : Power factor = real power / apparent
power. Linear load power factor of electric heaters and light bulbs for one,
many devices real power and apparent power difference is very small, negligible,
like capacitive equipment such as the lighting of this difference is very
important. Recent PC Magazine, a study showed that the lamp typical power factor
of 0.65, apparent power (VA) Power (Watts) 50%. 2, apparent power, apparent
power: AC voltage and AC current of the product. Formula is expressed as: S =
the UI. Where S is the rated output power, the unit is VA (voltammetry); U is
the rated output voltage, the unit is V, 220V, 380V, etc.; I is the rated output
current, the unit is A The apparent power includes two parts: the active power
(P) and reactive power (Q). The active power is directly acting the part. Such
as to cause the lamp lights up, the motor rotates, so that the electronic
circuit work. After doing work of this power into heat, people feel that some
people have an illusion, as the active power to apparent power, everyone knows
the active power is only apparent part of the power, expressed by equation : P =
Scosθ = UIcosθ = UI • F, http://charleskmong.surftownlabs.se/2012/07/28/led-bulb-lights-sales-e-panel-suppliers-have-started-to-de-cheap-led-bulbs/
.
Where P is active power, the unit is W (watts); F = cos θ is called the power
factor, and θ is the phase when the nonlinear load voltage and current phase.
Reactive power is stored in the circuit, but is not directly acting the part of
power, expressed as: Q = Ssinθ = UIsinθ. Where, Q is the reactive power, the
unit is var (lack of). Reactive power for lighting and all other electronic
circuits rely on DC voltage, leaving the reactive power is simply not work.
General users that the lamps and the like devices will require the active power,
without the need for reactive power. Since the reactive power is not acting, you
want it and where to use, http://ameblo.jp/johnsondelphine/entry-11313904444.html
.
So of course they think that the power factor is one of the lamp. Because it
gives the maximum output power. However, the reality is not the case. A lamp
when the AC mains input rectifier, pulsating DC voltage, if the ripple voltage
of any processing, it is provided directly to the lamp, no doubt, the circuit
did not work. When the lamp power factor close to 1, but this is what to use it.
In order for the lighting circuit to work properly, must provide a smooth DC
voltage. "Smoothing" must be performed by the filter capacitor connected to the
lamp rectifier behind to complete. This filter is like a reservoir capacitor
which must be stored a sufficient number of charge, when the gap between the
half-wave rectifier circuit voltage remains uninterrupted, able to maintain a
normal level. In other words, even if the input electrical energy between two
half-wave pulse Uc voltage levels without a significant change, this function is
achieved by the energy storage capacitor to this part of the storage capacitor
The energy is reactive power. Therefore, the lighting is to rely on the support
of reactive power in order to ensure that the circuit is correct use of active
power to achieve normal use. Therefore we can say that the lamps not only need
active power, reactive power, both are indispensable, LED
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