Abstract: In the equipment transformation of single crystal furnace, it is feasible to replace the Ukrainian instrument with the A1-708P instrument of Xiamen Yudian under the condition of the process. Taking full advantage of the functions of the A-708P instrument and using a reasonable programming method, satisfactory results were obtained. The programming table and the temperature control circuit diagram are given in the paper. (A1-708P instrument was later upgraded to A1-808P instrument)

Keywords: equipment modification program, single crystal furnace time setting

Introduction: In 1995, our unit purchased a single-sulphide cadmium telluride single-crystal furnace from Ukraine. The temperature controller used in the single-crystal furnace equipment is a meter composed of many discrete components. The circuit is complicated and has many faults, which often affects the operation of the equipment. . In 1998, our unit decided to renovate this single-crystal furnace equipment and replace Ukrainian non-standard instruments with standard instruments.

First, the selection of instruments

Through the investigation, we decided to replace the Ukrainian instrument with the domestic Yudian A1-708P instrument or the British Continental 818 instrument. At that time, in the domestic single crystal furnace equipment, the European 818 instrument was used. In other words, it is no problem to replace the Ukrainian instrument with the Euro 818 meter. Because the price of European instruments is expensive, I want to use domestic instruments instead of foreign instruments.

I analyzed the performance of the A1-708P meter and compared the performance and price of the A1-708P meter and the Continental 818 meter. Firstly, it is proposed whether the A1-708P instrument can meet the process requirements of the cadmium telluride single crystal furnace. The mercury cadmium telluride crystal is the material required for the infrared device. The growth process of the crystal is about 30 days, and the length of the crystal growth time is determined by the process.

The setting time of the A1-708P meter is 9999 minutes, about 7 days; the time of the Euro 818 meter is set to 999.9 hours (minutes), about 42 days. Although the time setting of the A1-708P is not enough for 30 days, the A1-708P has 30 programs. If you fully utilize the 30-segment program function, you can meet the 30-day time requirement. In addition, the highest display temperature and lowest temperature resolution of the A1-708P meter can meet the process requirements.

Although the Continental 818 has many features, it is expensive. The price of each Euro 818 meter is 7,000 yuan, while the price of A1-708P is 1200 yuan per unit. Obviously, the performance price ratio of A1-708P is high.

In 1998, Yuguang (formerly known as Yudian) was first exposed, but its popularity was not high. People lacked understanding of the field application of the A1-708P instrument.

At the beginning of 1998, I went to the Xiamen Yuguang Research Institute to participate in an academic exchange meeting. I saw that the Yuguang Institute had a spirit of hard work. After returning to Beijing, I will work on replacing Ukrainian instruments with A1-708P meters. The equipment transformation work was relatively smooth, and the task was completed soon. After years of equipment operation test, it proves that the A1-708P instrument has reliable performance and can fully meet the process requirements of the cadmium telluride single crystal furnace.

Second, the control principle of cadmium telluride single crystal furnace

The temperature programming of the A1-708P instrument is listed below, and the temperature control circuit diagram of the single crystal furnace is attached for reference.

Table 1: Temperature program table Celsius minutes C01=20.0 Temperature rise from room temperature 20.0 °C t01=60 After 60 minutes C02=250.0 liter to 250.0°C t01=120 After 120 minutes C03=250.0 Keep warm at 250°C t03=120 After 120 minutes C04 =450.0 l to 450.0°C t04=90 After 90 minutes C05=450.0 Insulation at 450.0°C t05=300 After 300 minutes C06=820.0 Rise to 820.0°C t06=8640 After 8640 minutes C07=820.0 Insulation at 820.0°C t07=8640 After 8640 Minute C08=820.0 Insulation at 820.0°C t08=8640 After 8640 minutes C09=820.0 Insulation at 820.0°C t09=8640 After 8640 minutes C10=820.0 Insulation at 820.0°C t10=4320 After 4320 minutes C11=820.0 Insulation at 820.0°C t01=360 After 360 minutes C12=350.0 drops to 350.0°C t12=600 After 600 minutes C13=20.0 drops to 20.0°C t13=-121 Stop

宇电A1-708P仪表在单晶炉设备改造中的应用

Figure 1: Temperature degree map

宇电A1-708P仪表在单晶炉设备改造中的应用

Figure 2: Single crystal furnace temperature control circuit diagram

Circuit description: AC power supply is used after step-down of transformer, output voltage is 25V, output current 28A, MJYD-JL-75 is thyristor intelligent module, including thyristor and phase shift control circuit, output maximum voltage is 450V, maximum current is 75A, L1 is Overcurrent protection fuse, RC is an overvoltage protection RC component. RW is an electric furnace wire.

The output of A1-708P is 0-10MA current. After 1K resistor, the output becomes 0-10V DC voltage, which satisfies the input voltage requirement of the thyristor module.

The S thermocouple is connected to the rear end of the A1-708P meter via a compensation wire.

Third, the feasibility analysis of the choice of temperature control system for single crystal furnace

In the single crystal furnace temperature control system, in addition to the A1-708P instrument is the core components, there are thermocouples, compensation wires, heating furnaces, power regulators and other important components. A thorough understanding of the performance of these components is also important to the proper selection of these components.

The current temperature instrument, economical and practical type of each hundred yuan, and the basic configuration price of each advanced instrument is several thousand yuan, if you add a few functional modules, the price can be tens of thousands.

For a certain process, it is sufficient to use a temperature meter that meets the technical requirements and can operate stably and reliably. It is not necessary to use a more advanced temperature meter.

It is scientific to select the type of temperature meter with a performance-price ratio indicator. Saving resources and making the best use of it is also the principle of selecting the type of temperature instrument.

Fourth, summary

Since the adoption of Yudian AI-708P as the main core control system, the control operation of the cadmium telluride single crystal furnace has been in good condition, and there is still no fault. It can completely replace the imported Continental 818 meter. Regardless of the actual operation situation or the cost performance, the choice of AI-708P can fully meet the requirements.

references:

1. "Temperature Measurement Technology" Wang Kuihan, Northeast Institute of Technology Press, 1991

2, "European 818 temperature regulator manual" Beijing Sitong company industrial control department 1985

3. "A1 Artificial Intelligence Industrial Regulator Instruction Manual" Zhou Yu with Xiamen Yuguang Electronic Technology Co., Ltd. 1998

4, "temperature testing technology and instrumentation" Chen Huansheng Water Conservancy and Electric Power Press 1985

About the author: Luo Youcheng, born in 1939, graduated from Huazhong University of Science and Technology, senior engineer of the 11th Research Institute of Beijing China Electronics Technology Group. He has been working on the temperature measurement control of various heating furnaces for many years.

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