Thermistors are temperature sensitive resistors that can be used in various applications such as temperature sensing, motor control, and domestic appliances. In this article, we will discuss the 3 wire thermistor wiring diagram in detail. We will cover the basics of thermistors, the functionalities of different wire connections, and provide a step-by-step guide on how to connect a 3 wire thermistor.
What is a Thermistor?
A thermistor is a type of resistor that changes its resistance based on temperature. Most thermistors have a negative temperature coefficient (NTC), which means that their resistance decreases as the temperature increases. Thermistors are widely used in temperature sensors, temperature compensation circuits, and thermal protection devices.
One of the significant advantages of thermistors over other temperature sensing devices is their high sensitivity. They can detect small temperature changes that other devices may not pick up. Additionally, thermistors have a relatively small size, making them suitable for applications where space is limited.
Types of Thermistors
There are two main types of thermistors: NTC and positive temperature coefficient (PTC). NTC thermistors are the most common type and have a negative temperature coefficient. PTC thermistors, on the other hand, have a positive temperature coefficient, which means that their resistance increases as the temperature increases.
NTC thermistors are widely used in temperature sensing and control applications. They are relatively inexpensive and have a broad temperature range. PTC thermistors are used in over-current protection devices and have a narrow temperature range.
Understanding 3 Wire Thermistors
A 3 wire thermistor is a type of thermistor that has three wires instead of two. These three wires are typically colored black, white, and red. Two of the wires are connected to a voltage source, and the other wire is connected to the voltage output of the thermistor.
The main advantage of 3 wire thermistors over 2 wire thermistors is that they compensate for the wire resistance between the thermistor and the measuring instrument. This compensation ensures that the measured temperature is accurate, even if there is a long distance between the thermistor and the measuring instrument.
Wiring a 3 Wire Thermistor: Step-by-Step Guide
Wiring a 3 wire thermistor is relatively easy, and you don’t need any special tools or equipment. Here are the steps to follow:
Step 1: Gather the Materials
Before you start wiring the thermistor, you need to gather the materials. These materials include the 3 wire thermistor, a voltmeter, a power source, and connecting wires.
Step 2: Connect the Power Source
Connect the power source to the thermistor. Connect the red wire to the positive terminal of the power source and the black wire to the negative terminal of the power source.
Step 3: Measure the Output Voltage
Use a voltmeter to measure the output voltage of the thermistor by connecting the positive probe of the voltmeter to the white wire of the thermistor and the negative probe to the black wire.
Step 4: Calculate the Resistance
Using Ohm’s law, calculate the resistance of the thermistor using the measured voltage and the known current.
Resistance (R) = Voltage (V) / Current (I)
Step 5: Connect the Thermistor to the Measuring Instrument
Connect the white wire of the thermistor to the positive input terminal of the measuring instrument, and connect the black wire to the negative input terminal.
Step 6: Measure the Temperature
Turn on the measuring instrument and measure the temperature. The temperature reading should be accurate, even if there is a long distance between the thermistor and the measuring instrument.
FAQs
| Question | Answer |
|---|---|
| What is the best way to connect a 3 wire thermistor? | The best way to connect a 3 wire thermistor is to connect the red and black wires to the power source and the white wire to the measuring instrument. |
| What is the difference between a 2 wire and a 3 wire thermistor? | A 2 wire thermistor has two wires, while a 3 wire thermistor has three wires. The additional wire in a 3 wire thermistor compensates for the wire resistance between the thermistor and the measuring instrument, ensuring accurate temperature readings. |
| What is the typical temperature range for NTC thermistors? | The typical temperature range for NTC thermistors is -40°C to 150°C. |
| What is the typical temperature range for PTC thermistors? | The typical temperature range for PTC thermistors is -40°C to 125°C. |
Conclusion
A 3 wire thermistor is a type of thermistor that compensates for the wire resistance between the thermistor and the measuring instrument, ensuring accurate temperature readings. Wiring a 3 wire thermistor is relatively easy, and you don’t need any special tools or equipment. We hope this article has provided you with sufficient information about 3 wire thermistor wiring diagrams to help you get started with your project.
