How to Choose PTC Thermistor?

Introduction of PTC Thermistor

PTC Thermistor heating elements are modern and even future high-tech products. It is widely used in the light industry, housing, transportation, aerospace, agriculture, medical treatment, environmental protection, mining, civil equipment, etc. Compared with heating elements such as nickel, chromium wire, or far infrared, it has excellent advantages.

1. There are special functions of constant temperature, temperature adjustment, and automatic temperature control

When an AC or DC voltage is applied to the PTC element to increase the temperature, the resistivity is very low below the Curie point temperature; once the Curie point temperature is exceeded, the resistivity suddenly increases, causing the current to drop to a stable value, reaching the automatic control temperature, Constant temperature purpose.

2. No burning, safe and reliable

The PTC element does not turn red when it is heated, there is no open flame (resistance wire is red with an open flame), and it is not easy to burn. When the surrounding temperature of the PTC element exceeds the limit, its power will automatically drop to the equilibrium value, and there will be no danger of burning.

3. Power saving

The energy input of the PTC element adopts a proportional type and a current limiting function, which saves electricity compared to the switching energy input of heating elements such as nickel-chromium wire.

4. Long life

The PTC element itself is an oxide, without the disadvantages of high-temperature oxidation of nickel-chromium wire, and without the fragile phenomenon of infrared tubes, and has a long life. And the porous type has a longer life than the non-porous type.

5. Simple structure

The PTC element itself automatically controls the temperature, without the need to add an automatic temperature control circuit device. In particular, our company's new product, the porous PTC, does not require other heat dissipation devices and conductive glue.

6. Wide voltage range

PTC components can be used normally under low voltage (6-36 volts) and high voltage (110-240 volts).

PTC Thermistor

Application of PTC thermistor

Low-voltage PTC components are suitable for all kinds of low-voltage heaters, instrument low-temperature compensation, heaters on automobiles, and computer peripherals.

The high-pressure PTC element is suitable for heating the following electrical equipment: electric heat preservation dish, shoe dryer, hot melt glue gun, rice cooker, electric hot shoe, electric mosquito repellent, intravenous heating, portable plastic sealing machine, steam hair comb, steam generator, Humidifiers, hair curlers, video recorders, photocopiers, vending machines, hot air curtains, hand warmers, tea dryers, plumbing heaters, travel clothes dryers, car paint booths, liquefied gas cylinder heaters, showers, Beauty appliance, electric heating table, milk bottle thermostat, electric moxibustion device, electric thermos, electric blanket, etc.

Brief introduction of thermistor technology and its application

1. Introduction to thermistor technology:

Since 1950, Heyman and others of Phillips in the Netherlands discovered that BaTIO3 ceramics can obtain positive temperature coefficient (PTC) characteristics after being semiconducting, and people have learned more and more about it. At the same time, its applications are becoming increasingly widespread, penetrating into various fields such as daily life, industrial and agricultural technology, military science, communications, and aerospace.

The reason for this situation is that the PTC thermistor has its unique electrical-thermal-physical properties. At present, it is in the stage of further optimizing the performance of PTC ceramic materials and further promoting the application of PTC ceramic components. The three promote each other. The application of the PTC thermistor is currently the most popular and promising new application technology.

Thermistors are divided into a positive temperature coefficient of resistance (PTC) and a negative temperature coefficient of resistance (NTC) thermistors according to the temperature coefficient of resistance.

PTC is the abbreviation of Positive Temperature Coefficient, which actually means a positive temperature coefficient. It is used for general batches of semiconductor materials or components with a large positive temperature coefficient of resistance. The practical use of PTC components began in the early 1960s. The earliest products were temperature compensation components for transistor circuits. Subsequently, serialized products used for motor overheating protection, color TV demagnetization, and current limiting, and constant temperature heating have been commercialized one after another, and large-scale production will soon be formed.

The development of PTC components in my country began in 1964, commercialized in the late 1960s, and the main products were serialized in the late 1980s and began to take shape. The application range of PTC components is very wide, and the application products to be developed are extremely rich. This has become the consensus of more and more experts.

2. Thermistor application:

Diode NTC Thermistor in circuit control and sensor applications:

Transistor temperature compensation circuit, temperature measurement, and temperature control circuit, overheat protection circuit, incubator, electric fan, color roll washing, kettle, electric water heater, electric blanket, fluorescent lamp, energy-saving lamp, battery charging, transformer winding, heater, delayer, Compressor, color TV, color display, over-current security, liquid level control, electronic ballast, program control switch, electronic component aging station

The application of PTC thermistors in electric heating appliances: heaters, room heaters, dryers (cabinet), tumble dryers, hand dryers, hairdryers, hair curlers, steam beauty appliances, rice cookers, mosquito repellents, hand warmers, Shoe dryer, pressure cooker, disinfection cabinet, coal gasification furnace, electric iron, electric soldering iron, plastic welding torch, sealing machine

Application of PTC thermistor in an automobile:

Electrical overload protection device, hybrid heater, low-temperature start heater, fuel heater, honeycomb heater, fuel level indicator, engine cooling water temperature detection meter.

How to choose PTC thermistor

Each type of thermistor has parameters such as "pressure resistance", "current resistance", "maintenance current" and "action time". You can choose according to the requirements of the specific circuit and the parameters of the product. The specific method is as follows:

1. First determine the maximum ambient temperature when the protected circuit is working normally, the working current in the circuit, the maximum voltage that the thermistor needs to withstand after the action, and the required action time and other parameters;

2. Choose "chip type", "radial lead type", "axial lead type" or "surface-mount type" according to the characteristics of the protected circuit or product;

3. According to the maximum working voltage, select the product series whose "withstand voltage" level is greater than or equal to the maximum working voltage;

4. According to the maximum ambient temperature and the working current in the circuit, select the product specification whose "maintenance current" is greater than the working current; 5. Confirm that the action time of the thermistor of this specification is less than the time required for the protection circuit;

6. Check the data provided in the specification to confirm that the size of the thermistor meets the requirements.

For example, a certain control circuit needs overcurrent protection, its working voltage is 48 volts, the current when the circuit is working normally is 450 mA, and the circuit's ambient temperature is 50°C. It is required that when the current in the circuit is 5 amperes, the current in the circuit should be reduced to below 500 mA within 2 seconds.