In the field of industrial instrumentation, accuracy is a crucial factor in determining the reliability and effectiveness of measuring devices. The accuracy of a measuring instrument is not only reflected in its real-time display but also in the output signal that it sends to a PLC or DCS system. This is where the accuracy of a pressure sensor's output signal becomes essential.
XIDIBEI pressure sensors are widely used in industrial settings and are known for their high accuracy and reliability. One of the most common output signal types for pressure sensors is the 4-20mA current signal. In this article, we will explore why this signal type is prevalent in pressure sensors.
In the past, voltage signals (0-10V) were the primary signal transmission type. However, voltage signals are susceptible to voltage drops due to long cable lengths, which can cause inaccuracies in the sensor's output signal. Additionally, voltage signals can be easily affected by electromagnetic interference, which can further disrupt the output signal's accuracy.
To address these issues, pressure sensors started using the RS485 communication protocol. RS485 signals have the advantage of requiring fewer cables, as a single communication cable can read all the sensor's parameters. This is particularly useful when dealing with multiple sensors in a single location.
However, the most common signal type used in pressure sensors is the 4-20mA current signal. The selection of 4mA as the starting point for the signal range is due to its ability to detect faults such as power loss or cable breaks. If the current is not 4mA at the zero point of the measurement range, it indicates that there may be a problem with the signal line or zero drift at the site.
The maximum signal current of 20mA is primarily based on safety, practicality, power consumption, and cost considerations. A spark caused by 30V voltage and 30mA current can ignite the lower explosive limit of dangerous gases. To ensure safety and follow traditional standards, many measuring devices are powered by 24V and limited to a current of less than 30mA. To leave some margin for error, the upper limit of the signal is set to 20mA.
In conclusion, the 4-20mA current signal is a common output signal type for XIDIBEI pressure sensors due to its high accuracy, reliability, and safety. While other signal types such as voltage signals and RS485 signals have their advantages, the 4-20mA current signal remains the most widely used signal type in industrial settings.