I. Overview Power isolation sensors/transmitters are small, high-performance power testing components (products) developed for power detection (monitoring) in engineering applications, aiming to improve the overall anti-interference capability of the system. Power isolation sensors/transmitters can isolate, measure, and transform electrical parameters such as high current, high voltage, power, frequency, phase angle, and electricity consumption in the field. They can also isolate, amplify, and transform various weak signals (such as various bridge signals), conditioning them to convert them into simulated signals such as voltage, current, and frequency conforming to international standards, or into digital signals, switch status signals, etc. These output signals can be connected to traditional pointer instruments, as well as modern digital automatic control instruments, various A/D converters, and calculator systems, thus forming a highly reliable industrial detection (monitoring) or control system. Because power isolation sensors do not require secondary development work from users, high voltage or high current signals can be directly connected to the product (through terminals, pins, or through-hole inputs) to obtain the corresponding output signals. Therefore, electrical isolation sensors, as modules for signal conditioning, isolation, and conversion, are ideal transmitter products in industrial control and data acquisition systems. With the continuous development of science and technology, the requirements for electrical isolation sensors in industrial control or detection (monitoring) systems are becoming increasingly stringent, especially in terms of product stability, detection accuracy, and functionality. Digital products, regardless of their performance or functionality (such as nonlinear correction and small signal processing), are incomparable to analog products. Therefore, the digitization of electrical isolation sensors is an inevitable trend. The following is a brief description of the working principle and digitization technology of electrical isolation sensors for your reference. II. Basic Working Principle of Electrical Isolation Sensors Since the objects detected by electrical isolation sensors are mainly current and voltage signals, the following mainly introduces the detection principles of current and voltage signals. 1. AC Signal Detection Principle AC signals are further divided into AC voltage and current signals. Figure 1 shows the block diagram of the AC current signal detection principle, and Figure 2 shows the block diagram of the AC voltage signal detection principle. The signals are isolated by CT and PT. Current is input via a through-hole method, and voltage is input via a terminal wiring method. Among them, CT is a current transformer and PT is a voltage transformer, with an output typically of 0-5V or 4-20mA. 2. DC Signal Detection Principle [align=center]Figure 3 is a block diagram of the DC signal detection principle.[/align] DC signals are divided into DC voltage and DC current. DC current is generally sampled through a resistor, and DC voltage is generally processed by reducing the voltage with a resistor. An isolated power supply powers the preamplifier. As can be seen from the above block diagram, whether it is an AC signal or a DC signal, the input and output are completely isolated. Generally, the input signal in the field is a large current or a high voltage. In this way, the power isolation sensor can completely isolate the field signal from the low-voltage data acquisition system, avoid the system from interference by strong signals, and thus improve the reliability of the system. III. Digital Technology of Power Isolation Sensor Figure 4 is a combined block diagram of an AC signal digital power isolation sensor, which consists of a transformer, data processing, interface, T/V conversion and output. ● There are two types of instrument transformers: current transformers and voltage transformers. Current transformers are generally through-hole type, while voltage transformers usually require a current-limiting resistor on their primary side. ● The data processing section is the core of product digitization. Currently, microcontrollers with integrated A/D converters are generally used, such as PIC16C74, MSP430, or ADUC812, so the circuit can be very simple. If the ADUC812 microcontroller is chosen, it can directly output a 0-5V voltage signal because it contains two 12-bit D/A converters internally. ● The interface section is the digital signal output conversion circuit. Currently, the RS-485 bus interface is widely used. The most commonly used interface chip is ADM483, which can connect up to 32 nodes. Of course, many other similar chips are also available now. RS-232 interfaces are generally implemented in two ways: one is to add an RS-485/RS-232 converter to the RS-485 network bus; the other is to directly integrate the RS-232 interface chip into the product. The latter method limits the product's application, preventing network integration and restricting communication to point-to-point. CAN-BUS is a rapidly developing bus technology. Its advantages include long transmission distances (up to 10km), no bus conflicts, multi-master operation, and good communication protocol compatibility; however, it is more expensive. ● T/V conversion is for compatibility with simulation signal acquisition input systems. Currently, PWM output is generally used, followed by T/V conversion to output 0-5V or 4-20mA simulation signals. ● The software mainly includes three functional modules: data acquisition, data processing, and communication protocol. Data acquisition mainly involves reading the A/D conversion results. Since the microcontroller has a built-in A/D converter, the program is relatively simple. Data processing mainly performs AC-to-DC conversion. Due to the limited processing speed of the microcontroller, we use the frequency tracking method to complete the conversion calculation. The communication protocol is generally selected by the user, such as MODBUS or ASCII format. IV. Conclusion The above briefly introduces the basic working principle and digitization technology of power isolation sensors. Because digital power isolation sensors can directly output digital values, many application systems can eliminate the need for an A/D acquisition module, thus reducing system costs. Therefore, the digitization of power isolation sensors not only improves product stability but also allows users to further reduce costs. Since there are many types of power isolation sensors, this article only introduces one type of AC signal power isolation sensor digitization technology. There are many methods for digitizing power isolation sensors. Currently, the most common method is to use microcontroller technology because of its flexibility and ability to achieve various functions. With the continuous development of integrated circuits, many dedicated chips have emerged. For example, in electricity meters, many dedicated chips are available, offering digital interfaces and pulse outputs. This article offers a superficial exploration of the digitization of power isolation sensor products, intended for reference only. It is hoped that this will serve as a starting point for further discussion and accelerate the development of digitization technology for power isolation sensors.