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NTC Thermistor and Motor Thermal Protector
2019/11/21 03:11:00



NTC thermistor produced by EXSENSE Electronic Technology Co., Ltd., has characteristics of great reliability, high sensitivity and high precision, which can effectively and quickly measure temperature and control temperature, plays an indispensable role in the motor thermal protector of household appliances. When the motor is operating, it has a high speed and a fast heating rise, so it must be protected by a thermal protector. To reduce costs, most manufacturers purchase regular models of motor thermal protector on the market to detect the temperature of the motor on the motor housing. However, the thermal protector manufactured by the existing technology, the thermal conductivity is poor, the temperature sense is relatively lagging, which is easy to cause the motor to burn out. However, replacing a package material or metal housing with a higher thermal conductivity, which will not only increase costs but also has bad temperature control effect.


In order to solve the above-mentioned technical problems, EXSENSE Electronics introduces a fast-response, high-accuracy, easy-installed, low-cost motor thermal protector. This thermal protector includes NTC thermistor, protective sleeve, wire, converter, controller, signal wire and fixture. The applied NTC thermistor is axial type glass sealed NTC thermistor, after it’s covered the silicone protective sleeve, use wire (Teflon wire) to make the thermistor and the converter form a circuit; The heat-resistant double-sided tape is used to attach the thermistor covered with a sleeve to the motor shell, and a layer of aluminum foil tape is pasted on the outermost layer, the converter is connected to the controller through the signal wire.


Because the using environment of motor is complicated, may be in a high-temperature, high-humidity, acidic or alkaline environment for a long time, and the vibration of motor itself is large, so the axial type glass sealed NTC thermistor needs to be protected, that is, the thermistor need to be covered with a protective sleeve. The protective sleeve is mostly silicone or Teflon U-type sleeve, the use of silicone sleeve, with advantages of low cost, easy to install, easy to form; The use of Teflon sleeve, with advantages of fast response of thermal conductivity, anti-corrosion. The heat-resistant double-sided tape or high-temperature adhesive, in the fixing of thermistor is simple to operate, easy to install, and low cost. The aluminum foil tape reflects the heat radiated outward from the measuring area back to the thermistor, making the temperature measurement more accurate and the result not distorted. And aluminum foil tape has characteristics of good stickiness, strong adhesion, anti-aging, so that the overall installation of thermistor is more reliable.


During operation, the converter of motor thermal protector converts the voltage value into a control signal, which then transmits the control signal through the signal wire to the controller, which controls the start-stop movement of the motor. Because the axial type glass sealed NTC thermistor close to the motor shell, which is very sensitive to the changes of temperature, and the thermistor to the temperature of the induction is continuous, the signal that finally reaches the controller is gradually varied, the controller can set a reasonable signal range to control the start and stop of the motor, to achieve the purpose of protecting the motor.


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