The Reasons Why You Need NTC Themistors

 As we all know, each type of resistance devices have their advantages, and their functions are different under different circuit requirements. In this article, we will talk about why more and more people are using NTC thermistors. Read on to learn more about their advantages.

The typical characteristic of thermistor is that it is sensitive to temperature and exhibits different resistance values at different temperatures. Positive temperature coefficient thermistor (PTC) has a higher resistance value when the temperature is higher, and negative temperature coefficient thermistor (NTC) has a lower resistance value when the temperature is higher. They are both semiconductor devices.

Advantages of NTC thermistors:

NTC thermistor is a type of temperature sensor that is widely used in industrial temperature measurement. Compared with the semiconductor integrated temperature sensor, NTC thermistor has the features of wide temperature measurement range, easy to use and low price. Compared with platinum thermistor or thermocouple, NTC thermistor has the characteristics of high sensitivity, simple circuit and low price.

The Role of NTC Thermistor in the Circuit:

In the rectifier and filter circuit, in order to avoid the instantaneous surge current generated by the capacitive load charging at the moment when the electronic circuit is turned on, a power NTC thermistor is usually connected to the power circuit. This can effectively resist the surge current the moment the electronic device is turned on. After completing the function of resisting the surge current, the resistance of the NTC thermistor will drop to a very small value due to the continuous action of the passing current, and the power consumption is very small so as to be ignored, and it will not affect the normal operation of the circuit. Therefore, in the medium and small power supply circuits, power NTC thermistors are widely used to resist bootup surge current.

All in all, NTC thermistor can suppress the surge current generated by boot-up. If you have any questions about the application of NTC thermistors, you;may;consult an experienced manufacturer for help.Dongguan Zhixu Electronics Co,. Ltd (JEC) manufactures a full range of high quality thermistors of competitive price. JEC is ISO9001 and ISO14001 certified. JEC's safety capacitors (X and Y series) and varistors have passed certification of main industrial countries across the world. JEC's ceramic capacitors and film capacitors are in line with environmental protection directives.

We are often imitated but never surpassed. JEC has over 30 years experience of manufacturing ceramic capacitors. You wouldn't regret if you choose us. If you have technical questions or need samples, please contact us.

The above info is provided by the marketing and department of Dongguan Zhixu Electronics Co., Ltd.;(JEC). For more information, please visit the News section on our official websites.

Common Causes Of Thermistor Failure

Thermistors are found in hairdryers, refrigerators, and cars, so they must work properly. They are used as temperature sensors, and they are also very useful for protecting current. What happens when the thermistor starts to show inaccurate readings?

To determine whether a thermistor is broken, you can monitor two different things. It will help you find incorrect readings or temperature fluctuations, which are impossible under normal working conditions. There are several factors that can cause such drastic changes in temperature, but it can also be a thermistor failure.

When you are driving, have you noticed that your air conditioner blows cold for a while, and then it stops working? The thermistor inside the vehicle's HVAC system is designed to automatically adjust the temperature, but when the thermistor fails, the system may work intermittently.

The most common cause of thermistor failure is an open circuit, which is caused by the mechanical separation between the lead material and the resistive element. This is caused by improper handling, thermal damage, and thermal mismatch. Over time and use, the thermistor can display incorrect temperature. In many cases, it is recommended to replace old, failing equipment.

How to know if the thermistor is bad?

In most cases, it is easy to know when the thermistor needs to be replaced. When a thermistor fails, it will display the incorrect temperature, or you will see impossible temperature fluctuations. For example, you might get a reading of 210 degrees Fahrenheit at first, then see the temperature drop to 189 degrees Fahrenheit, and then bounce back. Although other problems may be at play, if this happens frequently, the thermistor is likely to fail.

The working principle of the thermistor in the automotive AC system is very similar to that of the small thermistor in electronic products-but on a larger scale. They measure the temperature and send a resistance signal to the AC control module to let the system automatically adjust to keep the cabin at the temperature you set. The symptoms of thermistor failure are slightly different. When the thermistor in the car fails, the AC system will blow out cold air for a short time, or the blower will stop working normally.

What causes the thermistor failure?

Usually, the thermistor failure is due to an open circuit caused by the mechanical separation between the resistance element and the lead material. This may be caused by improper handling, thermal mismatch, or thermal damage. Another common cause of thermistor failure is aging. Over time, the thermistor circuit becomes more and more inaccurate, displaying incorrect temperature. In this case, it is easiest to choose alternatives.

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Temperature Sensors-Thermistors And Thermocouples

 Thermistor and thermocouple

Temperature sensors are very important in daily life, from factory work to fire prevention. Thermistor and thermocouple are two such temperature sensors.

A thermistor is a kind of thermistor whose resistance changes continuously and in small increments with the change of temperature. Thermocouples reflect the proportional changes in temperature through the different voltages generated between two different metals that are electrically bonded together. Both are good choices for temperature sensing and control. Choosing the best option depends on the type and specification of the application.

Four factors to consider when choosing thermistors and thermocouples as temperature sensors

Temperature range:

Both NTC thermistors and thermocouples can work in a wide temperature range, so they are ideal for a wide range of applications. NTC thermistors perform well in the operating range of -50 to 250°C, while thermocouples operate in the widest temperature range of -200°C to 1750°C.

Stability:

Applications with long-term goals need stability. Temperature sensors may drift over time, depending on their materials, construction, and packaging. For example, an epoxy-coated NTC thermistor can experience a drift of about 0.2°C per year; however, the drift of a sealed NTC thermistor is much smaller, about 0.02°C per year. On the other hand, thermocouples have a drift of about 1-2°C per year, which is mainly due to chemical changes in the sensor, such as chemical oxidation.

Accuracy:

NTC thermistor has high accuracy through incremental changes within its working range. Small temperature changes accurately reflect large changes in resistance per °C. When used for temperature control and compensation, thermocouples have low accuracy and require millivolt to a temperature conversion.

Application:

Both NTC thermistors and thermocouples can operate in a wide range of applications; however, NTC thermistors are usually found in life safety applications, such as fire detectors and thermometers, because they are accurate and stable. Due to the durability and lower production cost of thermocouples, thermocouples are more commonly used in industrial equipment.

NTC (Negative Temperature Coefficient) Thermistor

NTC thermistor is a temperature-sensing device made of sintered semiconductor material containing a mixture of various metal oxides. These materials have carriers, which allow current to pass through the thermistor, and the resistance changes in direct proportion to the change in temperature.

NTC thermistors produce higher resistance at lower temperatures. As the temperature increases, the resistance of the thermistor decreases. Because the resistance of the thermistor changes so much per °C, the smallest temperature change is quickly expressed as a predictable change in resistance.

The correct positioning of the thermistor requires the thermistor β (β) formula to calculate the relationship between resistance and temperature. This method uses two-point calibration to calculate the resistance vs. temperature curve and calibrate the resistance at two temperature points.

The output of the NTC thermistor is non-linear due to its exponential nature, but it can be linearized, depending on the application.

The overall performance and cost-effectiveness of NTC thermistors are an excellent choice for your temperature sensing solution.

They provide:

Versatility

Quick response

Exchangeability

Greater sensitivity

Stability and accuracy in its temperature range

Do You Know Thermistor?

The thermistor is a resistance thermometer, or the resistance of a resistor depends on the temperature. This term is a combination of "thermal" and "resistor". It is made of metal oxide, pressed into a bead, disc, or cylindrical shape, and then wrapped with an impermeable material such as epoxy resin or glass.

There are two types of thermistors: negative temperature coefficient (NTC) and positive temperature coefficient (PTC). For NTC thermistors, when the temperature increases, the resistance decreases. Conversely, when the temperature decreases, the resistance increases. This thermistor is most used.

The working principle of PTC thermistors is a bit different. When the temperature increases, the resistance increases, and when the temperature decreases, the resistance decreases. This type of thermistor is usually used as a fuse.

Generally, the thermistor can achieve high accuracy in a limited temperature range of approximately 50ºC near the target temperature. This range depends on the base resistance.

The thermistor is a temperature sensing element sintered with semiconductor materials. Its purpose is to make the large change in resistance proportional to the small change in temperature.

This kind of resistance can measure the voltage drop generated by a small measured direct current, or dc, through the thermistor.

These solid-state temperature sensors are actually as sensitive to temperature as resistors. This is where the name "resistance" comes from. It is a clear combination of the words "thermal" and "resistor".

Generally speaking, thermistors are composed of sintered ceramics, which are composed of highly sensitive materials and have reproducible characteristics of constant resistance and temperature.

NTC thermistor is a non-linear resistor, and its resistance characteristics change with temperature. The resistance of NTC decreases with increasing temperature. The way the resistance decreases is related to a constant called beta or ß in the electronics industry.

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