The efficiency of the motor is an important indicator for evaluating the energy utilization of the motor. The electric motor converts electrical energy into mechanical energy through the change of the magnetic field and outputs it through the rotating shaft. When the motor is connected to the power supply, a rotating magnetic field is generated in the core, and the hysteresis loss and eddy current loss generated by the alternating magnetic field in the core are called iron loss or iron loss. In the case of no-load, the iron loss plus a small amount of field current loss and mechanical friction loss is called the no-load loss of the motor. After the motor is loaded, the current flowing through the winding increases, and the heat loss that is consumed on the winding resistance is called load loss or copper loss. Motor efficiency is the ratio of the output power of the motor to the input power, which is the ratio of the output power of the motor to the sum of input power, no-load loss, and load loss. The efficiency of the motor decreases as the load decreases, and the motor with a larger capacity is higher.
Efficiency and power factor are important evaluation indicators for evaluating the energy utilization of electric motors and the economic operation standards of electric motors. At present, the efficiency and power factor indicators of electric motors are not marked on the nameplate of asynchronous motors. Therefore, in the general rules for energy consumption of energy-using products in Beijing It is necessary to label these two indicators on the product nameplate and in the product manual. Transformer machinery industry system has transformer manufacturers. The transformer transmits the electric energy from the primary to the secondary of the transformer through the magnetic field to meet the requirements of power transmission or user level. In most cases, the transformer is continuously operated continuously. When the transformer is unloaded, there are two parts of the iron loss for the excitation reactive current and the hysteresis and eddy current loss of the magnetic field. The magnetic flux increases linearly with decreasing frequency and increasing voltage. The iron loss increases approximately in proportion to the square of the flux, and is related to frequency and voltage. The iron loss is constant at a constant frequency and voltage. After the load is applied, a copper loss proportional to the square of the current is produced. From the power saving consideration of the transformer, it is necessary to minimize the no-load loss and load loss. The transformer is divided into an oil-immersed transformer and a dry-type transformer according to the structure, and is divided into a power transformer, a rectifier transformer, a voltage regulating transformer, an electric furnace transformer, a mining transformer, an explosion-proof transformer, and the like according to the use.
There are still some gaps in the design, manufacture and operation of wind turbines and pumps in China compared with the advanced level in foreign countries. In terms of actual power utilization, in addition to the large-capacity wind turbines on some power equipment and large-capacity special pumps in some enterprises, energy efficiency is generally low. In recent years, the state has introduced some preferential policies for the energy-saving renovation of fans and pumps, which has made significant achievements in energy-saving renovation of fans and pumps. According to the use of pumps and fans and the needs of the market, Beijing's “General Rules for Energy Consumption of Energy Products†refers to the pump products mainly referred to as various centrifugal pumps. The products of the fans include: centrifugal and axial ventilation. Machine, blower (including turbo blower) and compressor, the compressor referred to here does not contain reciprocating piston compressor and screw gas compressor. Centrifugal pumps: widely used in industrial and agricultural production and people's lives. Pump efficiency is an important indicator to evaluate the energy utilization of the pump. The efficiency referred to here is for the pump product. The efficiency refers to the operating efficiency of the pump body, not the efficiency of the pump unit.
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