Advantages of current signal (4~20mA signal)
1. The current signal is suitable for long-distance transmission, because the current signal is not affected by the resistance of the wire, while the voltage signal will be divided when the wire itself has resistance, resulting in inaccurate measurement. The maximum transmission distance of 4~20mA is generally controlled within 100m. For longer distances, it is recommended to use digital signals (485 communication).
2. Current signals generally use a two-wire system, and voltage signals generally use a three-wire system. In contrast, the two-wire system saves materials and reduces costs than the three-wire system.
3. For example, in complex on-site working conditions, the anti-interference ability of current signals is stronger than that of voltage signals. If there is interference, it is recommended to choose 4~20mA signal.
4. The current signal can appropriately exceed the range and output an inaccurate signal. For example, a pressure transmitter with a measuring range of 1mA and 4~20mA can output 24mA when the range is exceeded.
Depending on the power supply, the voltage signal is slightly different. For example, a pressure transmitter with a measurement range of 1mA and an output of 0~10V cannot output a signal above 9V when the power supply is 9V.
5.When wires are made of different materials (such as copper, nickel), a magnetic field will generally be generated, and the voltage signal will have errors, but the current signal will not.
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