How far can a 4-20 mA signal go?

20G conductors at about 12 ohms per 1000 feet (about 330m) means that 450 ohms of 20G conductor could be support 4-20mA as far as about 18,750 feet, about 3.5 miles or about 6km.

How far can a mA signal travel?

Analog Current Signals (0-20mA, 4-20 mA): Typical industrial position sensors with an analog current interface can tolerate significantly longer cable lengths compared to comparable voltage interfaces. Again making a somewhat broad generalization, analog current signals can tolerate cable lengths up to 500 feet*.

What is the upper limit for current to indicate a fault in 4-20mA current loop?

4-20 mA instrumentation and controls usually support a signal range slightly below 4 mA and above 20 mA. For transmitters, current values below 4 mA and above 20 mA are used to signal a fault such as a thermocouple burnout, Signal cable broken, Cable Low/High Resistance, Transmitter Failure or other sensor failure.

What is a 4 to 20 mA standard?

(4 to 20 MilliAmp) A point-to-point or multi-drop circuit mainly used in the process automation field to transmit signals from instruments and sensors in the field to a controller. It sends an analog signal from 4 to 20 mA that represents 0 to 100% of some process variable.

How does a 4-20mA transmitter work?

The PLC / DCS Analog Input card transmits a standard +24 V DC, 20 mA signal to Power the Transmitter. A one pair cable is used to power the transmitter and the same cable is used to receive the data in the 4-20mA current range. Transmitter receives +24V DC, more than 20mA signal in the loop.

How far can a 24V signal travel?

24V AC Power Max Wire Distance Chart

24 AWG 18 AWG
10 VA (417mA) 103 feet 451 feet
20 VA (833mA) 52 feet 225 feet
30 VA (1,250mA) 34 feet 150 feet
40 VA (1,667mA) 26 feet 112 feet

What is the difference between Hart and 4-20 mA?

HART provides two simultaneous communication channels, one analog, the other digital: A 4-20mA signal communicates the primary measured value (PV) as an analog value of current using the wiring that provides power to the instrument.

How do you measure a 4/20 mA signal?

To measure a 4-20 mA loop signal with a process clamp meter:

1. Access the signal wires (typically by removing the cover on transmitter).
2. Locate the mA signal and zero the mA clamp meter.
3. Verify the mA measurement, should be between 4 and 20 mA.

Is 4-20 mA analog or digital?

The most popular form of signal transmission used in modern industrial instrumentation systems is the 4 to 20 milliamp DC standard. This is an analog signal standard, meaning that the electric current is used to proportionately represent measurements or command signals.

Is a 4-20 mA signal AC or DC?

The 4-20 mA current loop has been the standard for signal transmission and electronic control in control systems since the 1950’s. In a current loop, the current signal is drawn from a dc power supply, flows through the transmitter, into the controller and then back to the power supply in a series circuit.