Oil Temperature Sensor
A temperature sensor is a sensor that can sense the temperature and change it to a useful output signal. Temperature sensor is the core part of temperature measurement instruments. The temperature sensor is divided into two categories by its measuring methods: contact type and non-contact type. And according to the characteristics of sensor materials and electronic components, it can also fall into the categories of thermal resistance and thermocouple. The oil temperature sensor is one of them.
The oil temperature sensor adopts thermistor, which uses semiconductor materials. Mostly of the sensors employ negative temperature coefficient -- the resistance decreases with increasing temperature. The change of temperature can cause significant changes of resistance, so it is the most sensitive temperature sensor.
However, the linearity of the thermistor is extremely poor, and its performance greatly depends on production process while no manufacturer now can offer a standardized thermal resistance curve. With small volume, Thermistors respond quickly to temperature changes. But thermistors require a current source, and the small size makes them extremely sensitive to self-heating errors. Thermistors measure the absolute temperature in two lines with high precision, but they are more expensive than the thermocouple, and the temperature range of the thermistor is smaller than that of the thermocouple. The resistance of a common used thermistor at 25 ℃ is 5 k Ω; the temperature change by 1 ℃ncauses the corresponding resistance change of 200 Ω. It is ideal for current control applications that need quick and sensitive temperature measurement. Small size is also beneficial to the applications which have space requirements, but it is a must to prevent self-heating errors. Thermistors also have their own measurement techniques. Small volume is an advantage for the thermistor, because it can stabilize quickly without causing heat load. However, it is also very weak due to its volume because the large current can easily cause heating. The thermistor is a resistive device, so any current source will lead to heating by its power, which is equal to the product of the square of the current and the resistance. So a small current source should be used. If the thermistor is exposed to high temperature, permanent damage will be caused.
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