二用一备变频系统组合式PLC控制器应用

The Application of Two-in-service and One-standby Combination Type of PLC Controller for Variable-frequency System

本文介绍二用一备变频系统组合式PLC控制器。系统主回路用二个变频器控制三个受控电机；控制回路采用PLC控制器，通过PLC梯形图程序，实现由二个变频器VF1-VF2对三个受控电机H1－H3进行二用一备任意组合状态的切换控制。本控制系统适用于集中控制场合，具有控制精度高、最大限度减少设备硬件成本的特点。

This article introduced the two-in-service and one-standby combination type of PLC controller for variable-frequency system. The main circuit consists of two frequency converters to control three motors. Besides, the control circuit employs the PLC c.ontroller to implement switching control on any combination of the three controlled motors M1-M3 by two frequency converters VF1-VF2 as two-in-service and one-standby stale via the PLC ladder diagram program. This control system is applicable fnr centralized control occasions, with the advantages of high control accuracy and minimized cost of hardware equipment.