Generally, manufacturers determine the resistance value of the temperature sensor according to the parameters of the microcomputer control motherboard of the air conditioner indoor unit, such as Haier's, room temperature is 23K, tube temperature is 10K, exhaust pipe temperature is 50K at 80 degrees, normal temperature is 400 ~ 600K When the resistance value decreases with increasing temperature and increases with decreasing temperature, the working principle is a pressure-type temperature sensor: measuring the temperature by using the property of the temperature-sensitive substance's pressure to change with temperature, is the basic of the pressure-type temperature sensor Temperature measurement principle. The resistance values of common temperature sensors of various brands are as follows:
Resistance of Haier air conditioner temperature sensor: Haier's, room temperature 23K, pipe temperature 10K, exhaust pipe temperature 50K at 80 degrees, normal temperature is 400 ~ 600K
Haier KFRD-48LW / Z2 has a ring temperature of 15K and a pipe temperature of 5. 7K are from actual measurements.
TCL air conditioner temperature sensor resistance: RT and PT of TCL are 5K. OT is 10K.
Resistance value of beautiful air conditioner temperature sensor: beautiful room temperature 7K, tube temperature 8K
Resistance of Shinco air conditioner temperature sensor: Shinco tube temperature is 8k at normal temperature. Zhigao normal temperature (25 degrees) is 5.5k
Resistance value of Mitsubishi air conditioner temperature sensor: When the temperature of Mitsubishi air conditioner is about 35 degrees, the ring and tube are about 5K.
Gree air conditioner temperature sensor resistance: Gree air conditioner tube temperature has 3 specifications, 5K, 10K, 15K.
Kelon air conditioner temperature sensor resistance: LG3681HT senses 10K and 5K tube temperature at 25 degrees. Kelon 35GW / N2F are 20K
Kelon Huabao's 20K room temperature and tube temperature defrost, which has always been used, Oaks ring temperature, tube temperature, external machine temperature are 5K
Working principle of air-conditioning temperature sensor:
1. Pressure type temperature sensor: It is the basic temperature measurement principle of pressure type temperature sensor to measure the temperature by using the property that the pressure of the temperature-sensitive substance changes with the temperature.
2. The expansion temperature sensor is made according to the principle of thermal expansion and contraction of objects. According to the shape of the expanding substance, it is divided into two types: solid expansion type and liquid expansion type. Mercury thermometers use the thermal expansion and contraction properties of mercury liquids to measure temperature. They are liquid expansion thermometers and bimetal thermometers are solid expansion thermometers and bimetals. The temperature measuring element of the thermometer is made by laminating two different metal materials with large differences in linear expansion coefficients. Because the linear expansion coefficient of the two metal pieces is not the same-so when the temperature increases, the bimetal piece will bend to the side with the smaller expansion coefficient, and the higher the temperature rise, the greater the bending. It is based on the relationship between the magnitude of the deformation displacement of the bimetal and the temperature change, and the pointer is driven by the lever magnification mechanism to indicate a small temperature value. At the same time, the recording pointer (pen) is driven by the lever, and the measured temperature is automatically recorded on the recording paper advancing at a uniform speed. The bimetal temperature juice has a simple structure, high mechanical strength, and low price, but it has low accuracy and limited range and range of use.
3. Thermal resistance temperature sensors: Thermal resistance temperature sensors are divided into two types: metal thermal resistance and semiconductor thermistor. The resistance value of most metal thermal resistors increases with increasing temperature and is said to have a positive temperature coefficient; while the resistance of semiconductor thermistors generally decreases with increasing temperature and is said to have a negative temperature coefficient. Since the resistance of conductors and semiconductors changes with temperature, the corresponding temperature can be measured by measuring their resistance
The characteristic of copper thermal resistance is that the relationship between its resistance value and temperature is linear, the temperature coefficient of resistance is relatively large, and the material
Easy to purify and cheaper: it has low resistivity, low accuracy, easy oxidation at high temperatures, and poor chemical stability;
Therefore, when the temperature is not high and there is no special restriction on the volume of the sensor, a copper thermal resistor can be used. The use of semiconductor thermistors as temperature sensors is becoming more and more widespread. There are two types of semiconductor thermistor indexing numbers: NTC (negative temperature coefficient) and PTC (positive temperature coefficient). There are many types of conductor thermistor muscles. The thermistor is usually made of oxides of some metals such as iron, nickel, molybdenum, titanium, magnesium, copper, etc. When the field is used, the distance between the controller and the thermistor can reach 800m, so it is especially suitable for temperature control in air-conditioning automatic control systems. Telemetry and remote control.
Good or bad temperature sensor measurement:
You can measure with the multimeter resistance file RX20K! The general sensor is 5K, 10K, 15K, and the resistance value is marked on the sensor. If the actual value is too large, the resistance value drifts. Or you can hold the head of the sensor with your hand, and then measure whether the resistance value has changed. If the resistance value has not moved, it means that it is bad!
When judging the performance of the air conditioner temperature sensor, the fixed-frequency air conditioner should be set in the forced cooling state, and the inverter air conditioner should be set in the trial operation state. If the air conditioner can run at this time, and the working current is basically normal, it can be considered that the temperature sensor is defective. A larger resistance value of the air-conditioning temperature sensor or a smaller resistance value of the compressor temperature sensor will cause the inverter output.