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.
4-20mA signal related products
DMK457 Marine Approved Pressure Transmitter
LMK382 Low Range IP68 Waste Water Level Transmitter
DMP334 Hydraulic Pressure Transducer for Very High Pressures
KX ATEX Intrinsically Safe SIL2 Approved Pressure Sensor
Advantages
- 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
Disadvantages
- 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.
4-20mA signal related products
LMP305 Borehole Level Transmitter
4-20mA Output Hydrostatic Level Transmitters & Sensors
SIAi-8 8 Channel Analogue Signal Input to RS-485 Modbus RTU Interface Converter
DMD331 Compact Differential Liquid Pressure Sensor