Pressure transmitters are essential components in industrial applications that measure non-electrical physical quantities, such as temperature, pressure, speed, and angle. Commonly, 4-20mA transmitters come in three types: four-wire transmitters (two power supply wires and two current output wires), three-wire transmitters (current output and power supply share one wire), and two-wire transmitters.
In this article, we will discuss the advantages of two-wire pressure transmitters, a type of pressure transmitter that has gained popularity in recent years. Here are some of the key benefits of two-wire pressure transmitters:
1. Less susceptibility to parasitic thermocouples and voltage drops: Two-wire pressure transmitters are less susceptible to parasitic thermocouples and voltage drops along the wire, which allows them to use thinner, less expensive wires. This can save a significant amount of cable and installation costs.
2. Reduced electromagnetic interference: When the output resistance of the current source is large enough, the voltage induced by the magnetic field coupling into the wire loop is generally insignificant. This is because the interference source causes a small current that can be reduced using twisted-pair cables.
3. Longer cable lengths: Capacitive interference can cause errors in the receiver’s resistance. However, for a 4-20mA two-wire loop, the receiver’s resistance is usually 250Ω, which is small enough to produce insignificant errors. This allows for longer and farther cable lengths compared to voltage telemetry systems.
4. Flexibility in channel selection: Various single-display or recording devices can be switched between different channels with different cable lengths without causing accuracy differences. This allows for decentralized data acquisition and centralized control.
5. Convenient fault detection: Using 4mA for zero-level makes it easy to detect open circuits, short circuits, or sensor damage (0mA status).
6. Easy to add surge protection devices: Surge protection devices can be easily added to the two-wire output port, making it safer and more resistant to lightning and surges.
In conclusion, two-wire pressure transmitters offer several advantages over other types of transmitters, such as reduced susceptibility to parasitic thermocouples and voltage drops, reduced electromagnetic interference, longer cable lengths, flexibility in channel selection, convenient fault detection, and easy addition of surge protection devices. With these benefits, two-wire pressure transmitters are becoming more popular in industrial applications that require accurate and reliable pressure measurements.
Post time: Apr-25-2023