I. Introduction
In recent years, with the rise of industries such as the Internet of Things, smart cities, and clean energy, as well as the demand for automation upgrades in the manufacturing industry, automated and information-based products have shown enormous market potential. Multi-channel signal acquisition technology has been widely used in these industries, serving as the " eyes " and " ears " of control systems .
Taking industrial automation control systems as an example, the control system needs to acquire multiple signals to judge and control the operating status of field equipment. These parameters include various operating data of the equipment, such as operating voltage, current, pressure, vibration, speed and other operating data, as well as various environmental parameters such as temperature and humidity of key components.
However, in actual industrial settings, the operation of numerous devices generates a host of harmful interferences. These primarily include surges, pulse bursts, and high-frequency electromagnetic signals. These interference signals couple to the control system through sensors on the field equipment, severely disrupting signal acquisition. At best, this affects sampling accuracy and causes false alarms; at worst, it can directly damage the control system.
II. How can we eliminate the impact of interference signals on the control system?
To eliminate the influence of interference signals on the control system, the following methods are commonly used:
1. The first step is to ensure physical isolation between the sensor and the control system, blocking the coupling path of interference signals to the control system. A common method is to achieve physical isolation between the sensor and the control system through a signal isolation module.
2. The second is to deal with the interference sources on site. By investigating and identifying the interference sources, it is generally caused by the switching of some high-energy equipment, which leads to dV/dt or dI/dt , and thus causes electromagnetic interference. It is quite difficult to deal with the interference sources on site.
3. Finally, filtering can also prevent most of the energy of the interference signal from passing through the control system, which can also improve the anti-interference characteristics of the system.
III. Signal Isolation Scheme in Multi-Channel Signal Acquisition
Block diagram of signal isolation scheme in multi-channel signal acquisition
The application solution, as shown in the diagram above, represents a relatively economical and reliable signal isolation method for multi-channel signal acquisition. The MCU in the control system uses a multiplexer 4052 to select and pass the electrical signals acquired by various field sensors. These signals are then transmitted in isolation via a signal isolation module , and finally sampled by an ADC and converted into digital signals. The selection signal of the multiplexer 4052 is implemented through optocouplers OP1 and OP2 . Both the 4052 and the optocoupler drivers are powered by the signal isolation module, eliminating the need for a separate isolation power supply.
The signal isolation module uses the TE_T/TN_T series, a voltage signal conditioning module developed by Mornsun Technology. It features high integration, high precision, high reliability, small size, and surface-mount packaging. Because it integrates signal processing, signal isolation, and power isolation functions, it simplifies circuit design and reduces design and debugging issues. The signal input and output meet 2000VAC electrical isolation voltage requirements, easily handling most industrial control applications. The pF- level isolation capacitors effectively block interference signals. Furthermore, it boasts extremely low linearity error (0.04%typ) and extremely low ripple noise (20mVtyp) . Its small 21*14.5*6.4mm surface-mount package meets customer SMT process requirements. It is widely used in high-precision signal isolation applications, especially in coal mines, power plants, and wind power industries.
IV. Summary
Multi-channel signal acquisition technology has a wide range of applications. Combining its own technological platform advantages and independent innovation capabilities, Mornsun provides a complete power supply solution to address signal interference issues, thereby improving the stability, security, and reliability of the system.
