If you are looking for a reliable and accurate way to measure process variables like temperature, pressure, and flow, using a 4 wire transmitter is a great option. A 4 wire transmitter is a type of instrument that can convert analog signals into digital signals, making it easier to transmit data and monitor process variables on a computer or control room. In this article, we will discuss everything you need to know about 4 wire transmitter wiring diagrams, including how to wire them correctly, common mistakes to avoid, and troubleshooting tips.
What is a 4 Wire Transmitter?
A 4 wire transmitter is an electronic device that is used to measure and convert process variable signals from a sensor into a 4-20mA current signal. This signal is then transmitted over long distances to a controller or computer for monitoring and analysis. Unlike a 2 wire transmitter, which is powered by the same loop that carries the signal, a 4 wire transmitter has a separate power source that provides constant power to the transmitter and isolates it from the signal loop.
4 wire transmitters are commonly used in hazardous and challenging environments where accuracy and reliability are critical. They are also widely used in industrial automation and control systems, as they provide a simple and cost-effective way to monitor and control process variables.
How to Wire a 4 Wire Transmitter
Wiring a 4 wire transmitter is not complicated, but it requires careful attention to detail. Before you start wiring, make sure you have the right tools and equipment, including a multimeter, screwdriver, and wire stripper. Here are the steps to follow:
Step 1: Mount the Transmitter
The first step is to mount the transmitter on a suitable surface using screws or bolts. Make sure the mounting surface is clean, dry, and stable. The transmitter should be mounted in a location that is accessible for wiring and maintenance, but also protected from moisture, dust, and vibration.
Step 2: Connect the Power Supply
Next, you need to connect the power supply to the transmitter. A 4 wire transmitter requires two power sources: one for the transmitter and another for the sensor. The transmitter power should be between 10-30VDC, while the sensor power should be between 5-12VDC. Connect the positive and negative wires from the power supply to the corresponding terminals on the transmitter.
Step 3: Connect the Signal Wires
Now it’s time to connect the signal wires. A 4 wire transmitter has four terminals: +/- for power, and +/- for signal. The signal wires should be connected to the +/- signal terminals on the transmitter. Make sure to strip the wires properly and tighten the terminal screws securely. You can use a multimeter to check for continuity and proper wiring.
Step 4: Test the Transmitter
Once you have wired the transmitter, it’s time to test it. Use a multimeter to measure the voltage and current output from the transmitter. The voltage output should be within the range of the power supply, while the current output should be between 4-20mA. If the readings are not within the expected range, double-check your wiring and troubleshoot any issues.
Common Mistakes to Avoid
Wiring a 4 wire transmitter can be tricky, and there are a few common mistakes that you should avoid. Here are some of them:
Using the Wrong Power Supply
Make sure to use the right power supply for your transmitter. Using the wrong voltage or amperage can damage the transmitter and affect its accuracy.
Incorrect Wiring
Double-check your wiring before testing the transmitter. Make sure the wires are properly stripped, tightened, and connected to the right terminals. Incorrect wiring can cause errors, distortions, and measurement inaccuracies.
Overloading the Circuit
A 4-20mA circuit can handle a maximum load of 500 ohms. If you overload the circuit by connecting too many devices or too long wires, it can cause voltage drops, current leaks, and measurement errors. Make sure to calculate the load and distance of your circuit before wiring the transmitter.
FAQs
| Question | Answer |
|---|---|
| What is the difference between a 2 wire and a 4 wire transmitter? | A 2 wire transmitter is powered by the same loop that carries the signal, while a 4 wire transmitter has a separate power source that isolates it from the signal loop. This makes the 4 wire transmitter more accurate and reliable, but also more complex to wire and troubleshoot. |
| Can I wire multiple 4 wire transmitters in the same circuit? | Yes, you can wire multiple 4 wire transmitters in the same circuit. However, you need to make sure that the load and distance of the circuit are within the specified range. You may also need to use isolation amplifiers or splitters to avoid interference and crosstalk. |
| What are some common applications of 4 wire transmitters? | 4 wire transmitters are commonly used in industrial automation and control systems, as well as in hazardous and challenging environments where accuracy and reliability are critical. Some common applications include temperature, pressure, and flow measurement in chemical plants, oil and gas refineries, and water treatment facilities. |
Conclusion
Wiring a 4 wire transmitter requires careful attention to detail, but it is an essential part of measuring and controlling process variables in industrial settings. By following the steps and tips outlined in this article, you can wire your 4 wire transmitter correctly and troubleshoot any issues that may arise. Always follow the manufacturer’s instructions and consult with a professional if you are unsure about anything.
