The 4-20mA wiring diagram is an essential component when it comes to controlling various industrial processes. This is a common wiring diagram used in industrial sensor instrumentation, field wiring, and control rooms. In this article, we will discuss what the 4-20mA wiring diagram is, how it works, and its importance in various industrial applications.
What is the 4-20mA Wiring Diagram?
The 4-20mA wiring diagram is a type of wiring used to communicate information from a sensor or a transmitter to a controller or an actuator. It is a simple and reliable method of transmitting analog signals. This diagram represents the current loop between two points in a circuit. In this case, the two points are a sensor and a controller or an actuator.
This diagram is commonly used in industrial settings because it is less affected by noise, it offers long-distance transmission, and it is not affected by voltage drops. It is commonly used in pressure sensors, temperature sensors, flow sensors, and level sensors.
How does the 4-20mA Wiring Diagram work?
The 4-20mA wiring diagram works by creating a current loop between a sensor and a controller or an actuator. The current loop is created by connecting the positive terminal of the power supply to the sensor and then connecting the negative terminal of the sensor to the controller or the actuator. The controller or the actuator is then connected to the negative terminal of the power supply.
The value of the measured parameter is converted into a current value between 4mA and 20mA. This is done through a conversion process that is built into the sensor or the transmitter. The current value is then transmitted through the loop and is read by the controller or the actuator. The controller or the actuator then processes the information and takes appropriate action.
Why is the 4-20mA Wiring Diagram Important?
The 4-20mA wiring diagram is important in various industrial applications because it offers several advantages over other wiring methods. These advantages include:
- Reliability: The 4-20mA wiring diagram is less affected by noise and voltage drops, making it more reliable.
- Long-distance transmission: The wiring diagram can transmit signals over long distances, making it suitable for large industrial settings.
- Compatibility: The wiring diagram is compatible with most controllers and actuators, making it easy to integrate into existing systems.
- Accuracy: The 4-20mA wiring diagram provides accurate measurements of various parameters.
The 4-20mA Wiring Diagram Components
The 4-20mA wiring diagram has three main components:
- The power supply
- The sensor or the transmitter
- The controller or the actuator
Power Supply
The power supply is responsible for providing the current to the circuit. The power supply can be an external power source or a loop-powered supply. The loop-powered supply draws its power from the current loop and is commonly used in low-power applications.
Sensor or Transmitter
The sensor or the transmitter is responsible for measuring the parameter and converting it into a current value between 4mA and 20mA. The sensor or the transmitter is connected to the power supply and the controller or the actuator through a current loop.
Controller or Actuator
The controller or the actuator is responsible for processing the information received from the sensor or the transmitter and taking appropriate action. The controller or the actuator is also connected to the power supply and the sensor or the transmitter through a current loop.
Frequently Asked Questions
What is the difference between 4-20mA and 0-10V?
4-20mA and 0-10V are both analog signals used in industrial applications. The difference between the two is in the way the signal is transmitted. 4-20mA is a current signal, while 0-10V is a voltage signal. 4-20mA is less affected by noise and voltage drops, making it more reliable over longer distances.
How far can a 4-20mA signal travel?
The distance a 4-20mA signal can travel depends on the resistance of the circuit and the power supply used. Generally, a 4-20mA signal can travel up to several kilometers without distortion.
How is the accuracy of the 4-20mA wiring diagram maintained?
The accuracy of the 4-20mA wiring diagram is maintained by calibrating the sensor or the transmitter. Calibration ensures that the sensor or the transmitter provides accurate measurements of the parameter being measured. Calibration is usually done periodically to maintain accuracy.
How is a 4-20mA signal converted to a digital signal?
A 4-20mA signal can be converted to a digital signal using an analog-to-digital converter (ADC). The ADC converts the analog signal into a digital signal that can be read by a microcontroller or a computer.
| Advantages | Disadvantages |
|---|---|
| Reliable over long distances | Requires more wiring than other methods |
| Not affected by voltage drops | Requires a power supply |
| Compatible with most controllers and actuators | Requires calibration |
| Accurate measurements of various parameters |
