A 4-20mA current signal has become very popular for many applications beyond it’s original intended purpose in the process industry. It is now used throughout industry as the preferred measurement and control signal for many different types of systems.
Despite the popularity of the 4-20mA signal, it is not the best solution for every application and here are some of the ‘for’ and ‘against’ reasons for determining whether it is the right type of signal for your application.
- It can be run over long distances with minimal signal losses compared to voltage type signals
- A varying current loop load impedance or supply voltage will not significantly affect the signal as long as it does not exceed recommended component limits
- Rugged signal with low electromagnetic susceptibility
- Saves on cable wire because it only needs 2 wires to function
- Live zero reading verifies sensor is electrically functional
- High power consumption compared to other analogue signal types
- Elevated output at zero reading
- Supply not isolated from output
- Increasing circuit load resistance, will reduce the supply voltage available to power the transmitter that is generating the 4-20mA signal.
- 100 bar Ex ia 4 to 20mA pressure sensor for 0 to 100 degC media temperature
- Retention pond 20 feet deep submersible water level sensor
- SIL 2 Approved Pressure Transmitters
- Low Pressure Range Intrinsically Safe Pressure Transmitters
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