How do I protect my outdoor temperature sensor?
1. Installation Location: Outdoor temperature sensors should be protected from direct sunlight and heavy rain to prevent impacts on measurement accuracy and sensor life. It is recommended that the sensor be installed in an open area away from buildings and trees to prevent interference from surrounding objects.
2. Protect from physical damage: The sensor should be protected from impact, collisions, and other physical damage to prevent measurement accuracy. When installing the sensor, select a suitable location and use a secure mounting bracket to ensure the sensor is securely fixed.
3. Temperature Calibration: Regularly calibrate outdoor temperature sensors to ensure accurate measurement results. Calibration methods can be found in the sensor’s manual or performed by a professional technician.
What is a 4-20 mA transmitter for temperature communication?
A 4-20mA temperature transmitter is a temperature transmitter that outputs a standard current signal of 4-20mA. These quantities must be converted into analog electrical signals before being transmitted to a control room or display device hundreds of meters away. A device that converts physical quantities into electrical signals is called a transmitter.
The most widely used method in industry is to transmit analog quantities using 4-20 mA current. 4-20 mA refers to a minimum current of 4 mA and a maximum current of 20 mA.
In industrial sites, signal conditioning and long-distance transmission can present the following challenges:
Because the transmitted signal is a voltage signal, the transmission line is susceptible to noise interference. Then, the distributed resistance of the transmission line generates a voltage drop.
Third, providing the operating voltage for the instrumentation amplifier in the field is also a challenge. To address these issues and avoid the effects of related noise, current is used to transmit signals because it is less sensitive to noise. A 4-20mA current loop uses 4mA to represent the zero signal and 20mA to represent the full-scale signal. Signals below 4mA and above 20mA are used for various fault alarms.
How to connect a PT100 to 4-20mA?
When installing and configuring a temperature transmitter, it is essential to ensure the correct connection between the transmitter and the PT100. Connections are always two-wire or three-wire. The two-wire system is suitable for shorter distances and minimal environmental interference. The three-wire system can reduce environmental interference and improve measurement accuracy.
When connecting, first connect the transmitter’s power terminals to a 24V DC power supply. Then connect the transmitter’s output terminals to the external circuit. To ensure the current output meets the 4-20mA standard.
Additionally, depending on the application requirements, the transmitter must be configured with appropriate parameters. It includes temperature range, zero calibration, and full-scale calibration.
These settings can be made using the transmitter’s built-in parameter settings interface or an external programmer. Correct parameter settings help ensure that the 4-20mA signal output by the transmitter effectively reflects the temperature changes measured by the PT100.
Temperature transmitters should be installed in locations away from adverse factors such as high temperature, humidity, and strong electromagnetic interference. During use, the temperature transmitter should be regularly inspected and maintained, and any components that may be faulty should be replaced promptly. This ensures stable operation and measurement accuracy.
