Fan knowledge without power and power factor
1 no power in AC circuits, electrical power load by power supply has two kinds; one is the active power, reactive power is not a. Active power is to keep the electric power needed by electric equipment in normal operation, the electric energy is converted into other forms of energy (mechanical energy, heat energy, electric power). For example: Motor 5.5 kW to 5.5 kW of electrical energy into mechanical energy, driven pump or threshing; lighting equipment that converts electrical energy into light energy for lighting, people live and work. Active power symbol P, units of watts (W), kW (kW), MW (MW). No power is more abstract, it is used to exchange the electric and magnetic fields in the circuit, and used to power the establishment and maintenance of the magnetic field in electrical equipment in. It is not a foreign power, but changed into other forms of energy. All electrical equipment of electromagnetic coil, must establish the field, will consume less power. For example, 40 Watt fluorescent lamp, in addition to more than 40 Watt Power (ballast also need to consume a part of active power) to light, no coil power supply ballast built with an alternating magnetic field also spent about 80. Because it does not work, can be called the "no work". Wattless power symbol Q, unit is spent (Var) or kilovar (kVar). No power is never useless power, it is of great use. The motor needs to establish and maintain a rotating magnetic field, make the rotor rotate, which drives the mechanical movement, the rotor magnetic field of motor is obtained from power wattless power established. The transformer also needs no power, a transformer coil can generate a magnetic field, the two secondary coil induced voltage. Therefore, reactive power, the motor does not rotate, the transformer can not transformer, AC contactor not pull. In order to illustrate this image, we give an example: rural hydropower projects need excavating earth, earth moving with a bamboo basket filled with soil, the soil is taken as the active power, pick empty bamboo basket is no power, and not a bamboo basket, bamboo basket of earth how to no di.? in normal circumstances, electrical equipment not only has active power from the power supply, but also need to have no power from the power supply. If no power supply in the power grid, electrical equipment is not enough reactive power to establish normal electromagnetic field, then, these electric equipment can not be maintained at rated conditions, with the terminal voltage of electrical equipment can be reduced, thus affecting the normal operation of electrical equipment.
No power supply, the adverse effects of electricity, mainly displays in: (1) reduce the output active power of generator. 2) to reduce the power supply ability of transmission, substation equipment. (3) cause line voltage loss and power loss increase. (4) resulting in low power factor and voltage drop, so that the capacity of electrical equipment not give full play to the. Wattless power transmission line from the generator and the high voltage supply, far can not meet the needs of load, so set the number of idle compensation device to supplement the wattless power in the power grid, to ensure that the user needs to wattless power, so that the electric equipment can work under rated voltage. This is the network needs to be provided with no power compensation device. Power load of 2 power factor of motor, transformer, which belongs to the existing inductive resistance and inductance load. Phase inductive load voltage and current have a phase difference, usually expressed in phase angle cosine cos φ. COS is called the power factor, also called rate. Power factor is the reflection of power user electric equipment reasonable usage, energy level and an important indicator of the level of power management. The calculation formula of the three-phase power factor is: cos φ -- power factor; P -- Q -- kW; active power, no power, kVar; S -- apparent power, kV. A; U -- with the rated voltage, power equipment V; I -- by running current of electrical equipment,
Power factor is divided into natural power factor, instantaneous power factor and power factor. (1) the natural power factor: refers to the power factor of electric equipment is not installed wattless power compensation equipment, or power factor of electric equipment itself. Load nature or natural power factor depends mainly on the electrical equipment, resistive load (incandescent lamp, electric resistance furnace) of high power factor, equal to 1, and the inductive load (motor, electric welder) power factor is lower, is less than 1. 2) the instantaneous power factor: refers to the power factor is read by the power factor meter in a moment. Instantaneous power factor with the size and voltage type, load of electrical equipment and constantly changing the level of. (3) the weighted average power factor: refers to the average value of the power factor in a certain period of time. The method of improving power factor has two kinds, one is improving the natural power factor, the other is to install the artificial compensation device