Common Applications of PTC Thermistors

A thermistor is a sensor resistor whose resistance value changes with temperature. According to the different temperature coefficients, it is divided into positive temperature coefficient thermistors and negative temperature coefficient thermistors. This article will tell you about the common applications of PTC thermistors.

1) Overvoltage, Overcurrent, Overload And Other Protection

PTC overvoltage, overcurrent, overload and other protections are widely used. In the direct series circuit of PTC, whe short-circuit occurs, the PTC thermistor can suppress the large current and protect the required components or circuits. Power transformers, various chargers, various instruments and other overcurrent and thermal protection occasions is a wide range of applications of PTC thermistors, especially in power equipment.

The PTC thermistor is connected in series in the circuit as an overcurrent protection element, that is, a protection transformer. When the circuit causes an excessive current due to a short circuit of a component or load for various reasons, the PTC thermistor will play a role at this time, which will inhibit the circuit from generating excessive current. It should be noted that factors such as rated zero-power resistance, operating temperature range, and component packaging should also be considered when selecting large reactive currents and operating voltages. Generally, it is appropriate to choose about 1.5 times the maximum working current when the circuit is working normally.

2) Start-Up Assistance For Motors, Motors, Compressors, etc.

The motor must overcome its own inertia when starting. For example, single-phase starting requires a large torque when starting. When the rotation is normal, the required torque is not very large. At this time, the auxiliary circuit can be added to the motor, which can be understood as an auxiliary source, which is equivalent to the electric vehicle needing more power to climb a hill.

For example, for a refrigerator compressor, the thermal resistance value becomes larger during startup, the startup winding of the compressor motor is energized, and the main winding of the compressor runs at the same time. When the resistance becomes large, the starting winding is equivalent to disconnection, and the compressor can operate normally.

The role of PTC thermistors is not only used in switching power supplies, but also in many aspects.

3) Degaussing Applications Such As Color TV Sets and Picture Tubes

The role of the PTC thermistor is to eliminate the influence of stray magnetic fields such as chromatic aberration and geomagnetism on the color picture. The automatic degaussing circuit of ordinary color TV is generally composed of two parts: degaussing coil and degaussing resistance. The PTC demagnetizing element works with its current-time characteristics. After the degaussing circuit is connected in series, since the initial resistance of the PTC element is small, the initial current passing through the degaussing coil is large, so that the coil generates a strong alternating magnetic field. Due to the self-heating of the PTC demagnetization element, the resistance will increase, and the current in the circuit will gradually decay, so that the alternating magnetic field in the coil will also be weakened, so as to achieve the purpose of demagnetization. This series of products are used in the degaussing circuit of color TV, color TV monitor and other crt.

The above content is the common application of PTC thermistor. Hopefully this article is helpful to everyone. Dongguan Zhixu Electronic Co., Ltd has over 30 years in the electronic components industry. Our factories are ISO 9000 and ISO 14000 certified. If you're looking for electronic components, welcome to visit our official website: www.jeccapacitor.com