What is the active power of LED street lamp? What is the relationship between input voltage and current and power?
Here, we define the phase angle advance as positive, and the phase angle lag as negative. The actual load is resistance, inductance, capacitance inductance capacitance of three types of complex, composite after referred to as "impedance", written in mathematical is: Z= R+j. where R is the resistance impedance, XL inductance, XC capacitance. If > 0, known as the "perceptual load"; conversely, if < 0 called capacitive load. Alternating current through the inductive load, the phase voltage of the alternating current phase advance; alternating current through the capacitive load, the lag phase alternating current AC voltage; electrical engineering definition of the power factor angle phi angle of power factor angle phi Cos phi is called the cosine value of power factor. For resistive load, the voltage and current of the phase difference of 0 degrees, therefore, the power factor of the circuit is 1 of the maximum; and pure inductance circuit, voltage and current phase difference of 90 degrees, and is a leading current voltage; in pure capacitance circuit, voltage and current phase difference is - 90 degrees. The current leading voltage. In the latter two circuits, the power factor is zero. For a general load circuit, the power factor is between 0 and 1. By mathematical impedance Z=, R+, J, if XL = XC, then Z= R, that is, impedance Z becomes a pure resistor, power factor is equal to 1.
When the alternating current through the load resistor, and the resistance of the AC voltage and AC current through the resistor is the same phase, and between them the phase angle phi = 0 degrees, while the active power consumption in the resistive load, power grid to supply energy. When the alternating current through the pure inductance load, phase AC voltage on the advanced phase of current 90 degrees and the angle between them phi = 90 DEG, produce reactive power in inductive load, power supply of electric energy in the inductor for temporary storage and magnetic energy back to the grid into electricity such a periodic cycle, results for grid is not energy, so that the "reactive power", but "reactive power" and "reactive current" still exist. When alternating current through pure capacitance load, also similar to this, but the phase AC voltage on the lag phase of current 90 degrees and the angle between them phi = - 90 degrees.
When the AC current is over load, the AC voltage added to the load generates a phase difference with the AC current through the load, and the concept of power factor is derived from it. People produce and live electricity from the grid, which provides alternating current of 50Hz or 60Hz. As AC load, there are three types of resistance, inductance and capacitance.
