论文部分内容阅读
目前国内外所生产的热电转换测量仪器中,对热电偶采用的保护电路有多种多样,但从原理上讲基本上可以分为双极性峰值检波保护电路和红外保护电路。双极性峰值检波保护电路位于输入衰减器和热电偶之间,以双极性峰值检波放大器监测输入电压,通过该保护电路控制衰减器和热电偶的通断,达到保护作用。这种电路简单、成本低。但只能用于10MH_Z以下。红外保护电路用红外感应元件监测热电偶的温升(见图1)。当输入电压超过量程,热电偶的温度将急剧升高时,紧贴热电偶外壳上的红外感应元件探测到这一温度变化,其直流电压输出增大,其信号经放大后,驱动相应的
At present, thermoelectric conversion measuring instruments produced at home and abroad have a great variety of protection circuits for thermocouples, but in principle, bipolar peak detection protection circuits and infrared protection circuits can be basically divided into two types. Bipolar peak detection protection circuit is located between the input attenuator and the thermocouple to bipolar peak detector amplifier to monitor the input voltage through the protection of the control circuit attenuator and thermocouple on and off to achieve the protection. This circuit is simple, low cost. But only for 10MH_Z or less. Infrared protection circuit with infrared sensing components to monitor the thermocouple temperature rise (see Figure 1). When the input voltage exceeds the range, the thermocouple temperature will rise sharply, close to the thermocouple housing on the infrared sensing element detects this temperature change, the DC voltage output increases, the signal is amplified, the corresponding drive