The traditional low-voltage motor protection is realized by the secondary circuit of relay protection. With the electromechanical "target=_blank> electromechanical industry, the motor is the most widely used, and the amount of electricity consumed in the total amount of power generation accounts for a large part. And all kinds of fans, pumps, air compressors account for more than half of the electricity consumed by the motor. The working environment of the motor of the power plant is harsh, and it is often prone to stall, short circuit, phase failure or long-term overload operation [3], Therefore, the controller should be able to protect and control the motor working in a harsh environment in real time to ensure the normal operation of the motor of the power plant. Cordless Reciprocating Saw Sabre Saw
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According to the "Technical Regulations for Power Plant Design of Thermal Power Plants" (DL/T 5153-2002), low-voltage factory motors should be equipped with phase-to-phase short-circuit protection, single-phase grounding protection (or single-phase grounding short-circuit protection), overload protection, and low Voltage protection, phase failure protection [4]. Therefore, the power plant project needs to measure the voltage and current full power parameters, and with the communication function, the controller needs to have self-diagnostic output, power-off output, fault record and other functions, which are summarized as follows:
1. Achieve perfect motor protection
The controller collects three-phase AC current, three-phase AC voltage, residual current, PTC thermal resistance, motor power "target=_blank> machine power and other power parameters, as well as various motion states during motor operation, etc. The controller internally processes the operation to achieve motor start timeout, overload, blockage, underload, phase failure, three-phase current imbalance, residual current (ground/leakage), temperature, external fault, phase sequence, overvoltage, undervoltage Comprehensive comprehensive protection such as under-power, over-power, and tE time, thus ensuring safe and continuous operation of power plant production [4].
2, to achieve a variety of motor control methods
The intelligent motor controller realizes a variety of different motor starting control through program control. The operation control authority realized by the controller includes: 1) RS-485 communication interface realizes remote control; 2) can be performed by buttons on the display module Operation control; 3) remote automatic control by controlling the DI terminal through the DCS system; 4) on-site local control of the DI terminal.
3. Real-time monitoring of motor operation on site
The power plant can observe the voltage, current, frequency and other parameters of the on-site motor equipment during operation and the current running status of the motor through the controller. The buttons on the operation display module set the starting mode of the power plant equipment (optional manual start, two Step start, two-speed start and protection mode).
4, to achieve communication functions
The controller can communicate with the host computer management system via the RS-485 communication interface through the Modbus-RTU or Profibus-DP communication protocol, and send the information to the background management system in the shortest time and issue an alarm signal to the fault information to make the operation. The personnel can find the cause of the fault in the first time and eliminate the fault in time to realize the real-time transmission function of the data of the motor equipment of the power plant.
The ARD3 intelligent motor controller adopts a modular product structure, including main body control module, transformer module and display module, and can be equipped with other functional modules and accessories of ARD3 intelligent motor controller according to the actual application in the industrial field. The ARD3 intelligent motor controller is installed in the low-voltage switchgear, and the electrical control components such as the transfer switch, the contactor and the motor starter constitute a motor control and protection unit, realizing remote automatic control, on-site direct control, LCD interface parameter indication, signal alarm The functions such as fieldbus communication improve the reliability and stability of the entire control loop and reduce the on-site commissioning and maintenance workload of the operator. The anti-shake and self-starting of the circuit can be realized by the optional anti-shake module. When the auxiliary power supply of the ARD3 intelligent motor controller is powered off, the controller can be continuously powered for 10s. At the same time, the AC380V power module can be selected for control. The AC380V is used as a place for auxiliary power.
Third, the application of ARD3 intelligent motor controller in the protection of low-voltage motor in power plant With the large-scale popularization and application of power plant DCS system, real-time centralized monitoring of industrial field motor has become one of the key points to realize industrial automation control. 1 is the fieldbus layout of the ARD3 intelligent motor controller in power plant applications. ARD3 intelligent motor controller provides users with RS485 (Modbus-RTU/Profibus-DP) communication interface, which can collect three-phase AC voltage, zero sequence current, thermal resistance value and motor power of motor in industrial field. " target=_blank> The ability and status monitoring information can be collected and distributed to the field bus. The operator can monitor the operation status of the industrial site in real time through the host computer, and realize the DCS remote control of the operator's operation interface [5]. .jpg)
Figure 1 Fieldbus layout of the ARD3 intelligent motor controller
As shown in Figure 2, the ARD3 intelligent motor controller engineering typical application scheme shows that after the circuit is powered on, the controller collects the switch KK1 signal, and the controller selects the remote control by reading the signal value of the control authority port (14, 15) or Control the motor starting locally. As shown in the wiring in Figure 2, if the signal collected by the controller port (15) is "1", the remote control motor is started; if the signal collected by the controller port (15) is "0", the local control is performed. The motor starts. The controller collects the signals of the three-phase AC voltage, three-phase AC current, zero-sequence current, contactor working state, circuit breaker working state and DCS cabinet emergency stop button SA, and the controller performs processing through the CPU after processing the circuit. After processing, according to the requirements of various protection performance, measurement parameters, control logic, data transmission, etc. of actual production requirements, the operation state of the motor on the 90L liquid crystal display interface and the display of some important power parameters in the control circuit of the power plant equipment are controlled. The value, as well as the working state of the control switch output, control and protect the starting mode and operation process of the motor equipment. The analog output port (35, 36) of the controller outputs an analog signal of 4-20 mA, and the DCS system reads the analog signal to determine the current running state of the motor. At the same time, as an individual device of the motor controller, in-situ protection is its basic function. The ARD3 intelligent motor controller can feedback the parameters of the on-site detection to the host computer in real time through the RS485 communication interface (25, 26), which is convenient for on-site maintenance personnel to remotely monitor and control the operation status of each point device in real time. .jpg)
Figure 2 Typical application scheme of ARD3 intelligent motor controller engineering
Fourth, the power plant chooses the effect of ARD3 intelligent motor controller
Protecting the operation of the motor and ensuring continuous uninterrupted operation of the motor is critical to production. The benefits of using the ARD3 intelligent motor controller in a power plant are:
1, the networking flexibility is high, easy to control
The motor controllers in the power plant have the same proportions as the application of the power distribution products, and they are inseparable in the process of realizing the networking. ARD3 intelligent motor controller provides RS-485 communication interface, and realizes a variety of protocol selection (Modbus-RTU/Profibus-DP). Communication between RS-485 and host computer can facilitate engineers to realize through computer background. Remote automatic control and online monitoring of the health of the equipment, etc.
2, real-time display parameters, convenient on-site inspection
The ARD3 intelligent motor controller adopts a modular product structure. The display module is installed in the DCS cabinet. The operating status of the current motor can be observed in real time through the LCD interface, which is convenient for the user to maintain and control the on-site motor.
3, energy saving
The role of the motor controller in energy saving and consumption reduction has begun to be valued by everyone. The ARD3 intelligent motor controller can automatically stop when the motor equipment is in an underloaded operating state, effectively avoiding waste of energy and saving money for the enterprise.
4. Information Centralization
The user can realize the real-time monitoring of the running status of each motor in the system through the communication module, and observe the operating parameters of the equipment at any time, such as: motor electric "target=_blank> machine current, voltage, motor running condition, motor electric" target=_blank> By analyzing the collected information, the user can perform real-time processing on the motor operation of each device, which improves the safety and reliability of the entire control system.
5, intelligent self-control protection
The ARD3 intelligent motor controller is flexible in use, and the alarm and protection parameters can be preset by software according to the actual operating conditions of the power plant equipment to avoid the impact of excessive protection on actual production. After the user selects the ARD3 intelligent motor controller, once the field motor fails, the controller controls the motor to stop running in time, and makes corresponding indications and records for various fault information, which is convenient for the user to query the fault information. In the event of a grid fault, a large amplitude fluctuation of the voltage or a short-term power failure is restored, and the motor controller can be restarted with the anti-shake function.
6. Record motor fault information to facilitate on-site problem analysis
Most of the motor equipment working in power plants are in high temperature, humidity and dusty conditions, and it is easy to malfunction. Once a fault occurs, it is difficult for the maintenance personnel to find the cause of the fault in the first time, and it takes a certain time, manpower and Material resources can analyze the cause of the failure. The ARD3 intelligent motor controller has powerful fault and event records, and operation management information saves a lot of time for field maintenance personnel, improves the work efficiency of maintenance personnel, and further improves the performance of the entire control loop.
V. Conclusion In the low-voltage motor protection and monitoring system of power plants, ARD3 intelligent motor controller is adopted to improve the automation level and reliability of the control loop, and also improve the comprehensive benefits of the enterprise, and achieve the unification of reliability and economy. . Moreover, with the continuous development of technology, ARD3 intelligent motor controller will play an increasingly important role in the protection and measurement and control operation of low-voltage motors in power plants.
references:
[1] Man Lianshan. Application of Low Voltage Motor Protection in Thermal Power Plants. Electronic Technology and Software Engineering. 2014(2)
[2] Yan Gang, Guo Yingchen. Application of intelligent motor controller in power plants. Huadian Technology. 2008(3)
[3] Zhou Zhong. Product selection and solution for smart grid customer power monitoring and power management system [M]. Beijing. Mechanical Industry Press. 2011.10
[4] Hu Gang. Application of Low Voltage Motor Protection in Thermal Power Plants. Enterprise Technology and Development. 2009(16)
[5] Zhang Yuwei. Application of ST500 intelligent controller in low-voltage motor protection of power plants. Technology Wind. 2011(6)
About the author: Zhang Juan, undergraduate, serving unit: Currently working for Shanghai Anke Rui Electric Co., Ltd. Contact phone, mobile phone, QQ
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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