【正文】 外文翻譯（原文） 1 Design and Implementation of PLCBased Monitoring Control System for Induction Motor Abstract： The implementation of a monitoring and control system for the induction motor based on programmable logic controller (PLC) technology is described. Also, the implementation of the hardware and software for speed control and protection with the results obtained from tests on induction motor performance is provided. The PLC correlates the operational parameters to the speed requested by the user and monitors the system during normal operation and under trip conditions. Tests of the induction motor system driven by inverter and controlled by PLC prove a higher accuracy in speed regulation as pared to a conventional control system. The efficiency of PLC control is increased at high speeds up to 95% of the synchronous speed. Thus, PLC proves themselves as a very versatile and effective tool in industrial control of electric drives. Keywords： Computercontrolled systems, puterized monitoring, electric drives, induction motors, motion control, programmable logic controllers (PLCs), variablefrequency drives, voltage control. I. INTRODUCTION Since technology for motion control of electric drives became available, the use of programmable logic controllers (PLCs) with power electronics in electric machines applications has been introduced in the manufacturing automation [1], [2]. This use offers advantages such as lower voltage drop when turned on and the ability to control motors and other equipment with a virtually unity power factor [3]. Many factories use PLCs in automation processes to diminish production cost and to increase quality and reliability [4]–[9]. Other applications include machine tools with improved precision puterized numerical control (CNC) due to the use of PLCs [10]. To obtain accurate industrial electric drive systems, it is necessary to use PLCs interfaced with power converters, personal puters, and other electric equipment 外文翻譯（原文） 2 [11]–[13]. Nevertheless, this makes the equipment more sophisticated, plex, and expensive [14], [15]. Few papers were published concerning dc machines controlled by PLCs. They report both the implementation of the fuzzy method for speed control of a dc motor/generator set using a PLC to change the armature voltage [16], and the incorporation of an adaptive controller based on the selftuning regulator technology into an existing industrial PLC [17]. Also, other types of machines were interfaced with PLCs. Thereby, an industrial PLC was used for controlling stepper motors in a fiveaxis rotor position, direction and speed, reducing the number of circuit ponents, lowering the cost, and enhancing reliability [18]. For switched reluctance motors as a possible alternative to adjustable speed ac and dc drives, a single chip logic controller for controlling torque and speed uses a PLC to implement the digital logic coupled with a power controller [19]. Other reported application concerns a linear induction motor for passenger elevators with a PLC achieving the control of the drive system and the data acquisition [20]. To monitor power quality and identify the disturbances that disrupt production of an electric plant, two PLCs were used to determine the sensitivity of the equipment [21]. Only few papers were published in the field of induction motors with PLCs. A power factor controller for a threephase induction motor utilizes PLC to improve the power factor and to keep its voltage to frequency ratio constant under the whole control conditions [3]. The vector control integrated circuit uses a plex programmable logic device (CPLD) and integer arithmetic for the voltage or current regulation of threephase pulsewidth modulation (PWM) inverters [22]. Many applications of induction motors require besides the motor control functionality, the handling of several specific analog and digital I/O signals, home signals, trip signals, on/off/reverse mands. In such cases, a control unit involving a PLC must be added to the system structure. This paper presents a PLCbased monitoring and control system for a threephase induction motor. It describes the 外文翻譯（原文） 3 design and implementation of the configured hardware and software. The test results obtained on induction motor performance show improved efficiency and increased accuracy in variableload constantspeedcontrolled operation. Thus, the PLC correlates and controls the operational parameters to the speed set point requested by the user and monitors the induction motor system during normal operation and under trip conditions. II. PLC AS SYSTEM CONTROLLER A PLC is a microprocessorbased control system, designed for automation processes in industrial environments. It uses a programmable memory for the internal storage of userorientated instructions for implementing specific functions such as arithmetic, counting, logic, sequencing, and timing [23], [24]. A PLC can be programmed to sense, activate, and control industrial equipment and, therefore, incorporates a number of I/O points, which allow electrical signals to be interfaced. Input devices and output devices of the process are connected to the PLC and the control program is entered into the PLC memory (Fig. 1). Fig. 1. Control action of a PLC. In our application, it controls through analog and digital inputs and outputs the varying loadconstant speed operation of an induction motor. Also, the PLC continuously monitors the inputs and activates the outputs according to the control program. This PLC system is of modular type posed of specific hardware 外文翻譯（原文） 4 building blocks (modules), which plug directly into a proprietary bus: a central proces