This Power & Electricity Masterclass training course, this found hidden within the user manual of one digital power meter.
The author, electrician engineer with Taiwanese origin, this small Taiwanese brand this is now inactive.
Today and after web translation, ITTSB Europe deliver to your eyes this high quality and short training course.
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Power factor is an important technical indicator.
Power factor is a measure of the efficiency of electrical equipment.
A low power factor indicates that the circuit uses a large amount of reactive power for alternating magnetic field conversion, which reduces the efficiency of electrical equipment.
The utilization rate increases the power loss of the power line.
Therefore, the power supply department has certain standard requirements for the power factor of the power user.
Take electrical equipment as an example.
For example, the power of the electrical equipment is 100 units, that is, there are 100 units of power transmission.
However, because most electrical equipment is not a pure resistive load, there is inherent reactive power loss, so only 70 units can be used.
Unfortunately, although only 70 units are used, 100 units are charged.
The electric energy meter of our daily users measures active power, not reactive power, so there is no saying that you have to pay 100 units for using 70 units.
If you use 70 units of active power, you pay for 70 units of consumption.
In this example, the power factor is 0.7.
This reactive power mainly exists in motor equipment (such as exhaust fans, pumps, compressors, etc.), also known as inductive load.
Power factor is a measurement standard for motor efficiency.
Each motor system consumes two types of power, active power and reactive power.
The higher the power factor, the higher the active power.
The higher the ratio of efficiency to total power, the more efficiently the system operates.
In addition, the power factor represents the degree of consistency between voltage and current.
In an inductive load circuit, the peak value of the current waveform is greater than the peak value of the voltage waveform.
The separation of the two waveform peaks can be expressed as the power factor.
The lower the PF, the greater the separation of the two waveform peaks.
Active Power
The input electrical energy is effectively consumed and converted into heat energy, light energy, mechanical energy or chemical energy, which is called active power.
Average power The instantaneous power of AC is not a constant value.
The average value of power in a cycle is called active power, represented by the letter P, and the unit is Watt (W).
Usually, the power we refer to refers to active power, such as the power of household appliances, lighting sources, etc.
Apparent Power = VA
Reactive Power
Reactive power is a bit abstract.
It reflects the amount of energy stored in the circuit.
It is used to exchange the electric field and magnetic field in the circuit.
The electrical power used to establish and maintain the magnetic field in electrical equipment. It does not do work externally, but is converted into other forms of energy.
A reactive load, that is, an electrical device with an electromagnetic coil, consumes reactive power to establish a magnetic field.
For example, a 40-watt fluorescent lamp consumes in addition to more than 40 watts of active power (the ballast also consumes some active power) to generate light, it also requires about 80Var of reactive power to supply the ballast.
The coil is used to create an alternating magnetic field.
Since it does not do work to the outside, it is called "reactive power".
The symbol of reactive power is Q, and the unit is VAR of KVAR.
Reactive power is by no means useless power, it is very useful.
The motor needs to establish and maintain a rotating magnetic field to make the rotor rotate.
To drive mechanical motion, the rotor magnetic field of the motor is established by obtaining reactive power from the power supply.
The transformer also needs reactive power.
The primary coil of the transformer generates a magnetic field and induces voltage in the secondary coil.
Therefore, without reactive power, the motor it does not rotate, the transformer cannot transform the voltage, and the AC contactor will not close.
To illustrate this problem, here is an example:
Rural water conservancy construction requires excavation and transportation of earth. When transporting earth, bamboo baskets are filled with earth.
The earth carried away is like active power, and the empty bamboo baskets are like it is reactive power.
Bamboo baskets are not useless.
Without them, how can the soil be transported to the embankment?
In the complex power of a sinusoidal current circuit, the reactive power is the imaginary part of the complex power:
S=P+JQ
Where:
S is apparent power
P is active power
Q is reactive power
The maximum value (amplitude) of the sine quantity is equal to 0.707 times its effective value.
True RMS measurements are usually performed using digital RMS converters, using high-speed analog-to-digital converters (ADCs).
The input signal is quantized and then the digital RMS value is calculated according to a formula.
Where is the number of samples in one cycle = sampling sequence.
Topic: Power & Electricity Masterclass training course for Free (Read 162 times)
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