# What is a 4/20 mA signal?

## What is a 4/20 mA signal?

(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.

### Why do we use 4 to 20 mA signal?

For conversion of current from 4-20 mA to 1-5 V needs a 250 ohms resistance. 4. Reason for 20 mA: 20 mA is used as maximum because the human Heart can withstand up to 30 mA of current only. So, as a safety point of view, 20 mA is chosen.

What voltage is a 4-20mA signal?

The range of voltage over which the loop will function is called its Compliance Voltage. Common values for 4-20 mA loop supplies are 24VDC or 36VDC.

Reading 4-20mA current loop sensors using Arduino is much easier than you might think. so when you connect the 4-20mA current receiver circuit in the series and read the sensor it will read 4ma when the pressure is 0 psi and it will read 20mA when the pressure is 50 psi.

## What is 20 mA in a?

Milliampere to Ampere Conversion Table

Milliampere [mA] Ampere [A]
20 mA 0.02 A
50 mA 0.05 A
100 mA 0.1 A
1000 mA 1 A

### How far can a 4-20mA signal travel?

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 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.