电子指针式两路兆欧表的设计  

作　　者：游雨云[1] 程智君[1] 

机构地区：[1]上饶职业技术学院,江西上饶334109

出　　处：《科技创新与应用》2020年第30期41-42,共2页Technology Innovation and Application

摘　　要：本设计使用变压器降压,获得三路低压正弦交流电,采用TL431实现两路高精度基准稳压,为绝缘电阻提供电压,另一路构成双电源,为工作电路供电电压。使用低输入失调电压运放OP07驱动两路表盘分别指示照明和动力的绝缘对地电阻值。电路共设置了4个报警档位和1个自检档位,当绝缘电阻值低于设定值时,报警电路指示灯亮,并通过继电器输出报警信号,自检档位用于表头显示校准。STC15W104为主控芯片,控制按键切换报警档位,同时输出PWM信号经RC滤波转换为直流比较基准电压。This design uses transformer step-down to obtain three low-voltage sinusoidal alternating current, uses TL431 to achieve two high-precision reference voltage stabilization, provides voltage for insulation resistance, and the other constitutes a double power supply to supply voltage for the working circuit. The low input offset voltage operational amplifier OP07 is used to drive the two dials to indicate the insulation-to-ground resistance of lighting and power respectively. The circuit has a total of four alarm gears and one self-check gear. When the insulation resistance is lower than the set value, the alarm circuit indicator light is lit, and the alarm signal is output through the relay. Then, the self-test gear position is used for the display and calibration of the meter.STC15 W104 is the main control chip, which controls the button to switch the alarm gear, and at the same time, the output PWM signal is converted into DC reference voltage by RC filter.

关 键 词：TL431 报警档位 STC15W104 PWM信号 

分 类 号：TM934.1[电气工程—电力电子与电力传动]