Description
Excitation control unit Including excitation regulator, forced excitation, forced demagnetization and demagnetization, etc., it will automatically adjust the excitation current output of the power unit according to the operating state of the generator to meet the needs of the generator operation. ■ Excitation regulator: By it to feel the voltage, current or other parameters of the generator changes, and then exert control on the excitation power unit, excitation regulation, to maintain the generator terminal voltage within the given range. Automatic mode: Compare the actual terminal voltage of the generator with the automatic set value to control the terminal voltage. Manual mode: Compare the actual excitation current of the generator with the manual set value to control the excitation current (when the PT fails).
Excitation power unit It provides DC excitation current to the excitation winding of synchronous generator and establishes DC magnetic field. ■ According to the supply mode of excitation power supply, there are the following modes of excitation ● DC excitation system ● AC excitation system ● Static excitation system ■ According to the supply mode of excitation current, divided into ● Separate excitation generator, a generator that obtains excitation current from other power sources ● Self-excited generator, a generator that obtains excitation current from the generator itself
Brushless excitation system Brushless excitation system (Brushless means that there is no carbon brush, slip ring and other rotating contact parts) ● diode brushless excitation system The rotary rectifier is a diode ● Thyristor brushless excitation system The controlled, rotating rectifier is a thyristor It is generally composed of AC exciter, permanent magnet secondary exciter, rotary rectifier, thyristor rectifier, etc.
The Programmable Logic Controller was first introduced in the United States in the late 1960s, when it was called the Programmable Logic Controller (PLC), which was used to replace relays. To perform logical judgment, timing, counting and other sequential control functions. The concept of PLC was proposed by General Motors. The basic design idea of PLC is to combine the advantages of computer function perfect, flexible, universal and relay control system simple and easy to understand, easy to operate, cheap and so on, the controller hardware is standard and universal. According to the actual application object, the control content is compiled into software and written into the user program memory of the controller, so that the connection between the controller and the controlled object is convenient.
PLC features and functions
(1) The main characteristics of plc. The characteristics of plc are: reliable work, fast running speed, building block structure, flexible combination, good compatibility, simple programming and generation, rich, strong network function.
(2) The main functions of plc. plc system can well complete the industrial real-time sequence control, condition control, counting control, step control and other functions; It can complete analog/digital (a/d), digital/analog (d/a) conversion, data processing, communication networking, real-time monitoring and other functions. Years of practice shows that plc, reliable, is designed for the factory, with reinforced components according to the requirements of the working environment, real-time scanning practice and fault diagnosis function, easy troubleshooting, won the preference of users. What makes a plc so reliable is a real-time core or operating system of executable relay logic, sequential function diagrams, function blocks, structured text, command catalogs, or a combination thereof. In case of failure, the built-in device can maintain mechanical damage and maintain an orderly and predictable sequence.
2.4 The development trend of plc: there are extremely fast logical operations and logic control, sequence control capabilities, reliability in discrete control, convenient and easy to learn programming methods, so that it has an undisputed position in the field of industrial automation based on discrete.
The company focuses on DCS, PLC, robot, large servo four systems
The main products are various modules/cards, controllers, touch screens, servo drivers Company advantage: Supply imported original products, professional production of spare parts One year warranty, fast delivery time, complete supply !！！ ① 24 hours email response (12 hours); ② For shipment outside Asia, please contact the seller.
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