1. Temperature sensing cable temperature measurement. The temperature sensing cable is placed in parallel with the cable. When the temperature of the cable connector exceeds a fixed temperature value, the sensing cable is short-circuited and an alarm signal is issued to the control system. The shortcomings of ordinary temperature-sensitive nylon cable joints are: destructive alarm, fixed alarm temperature, incomplete fault signal, inconvenient system equipment and protection work, equipment is easy to damage; analog line type temperature sensing cable can only use a certain part of the line segment as alarm Unit, so it can't be arbitrarily positioned to be an alarm signal at a certain point.
2. Thermistor type temperature measurement. The thermistor can be used to measure the cable temperature value, but it is an analog output. The signal amplification and A/D conversion are required to be accepted. Each thermistor requires independent wiring, the wiring is messy and the thermistor is easy. Damage, large amount of protection, the sensor does not have self-test function, the demand is often verified.
Infrared sensing temperature measurement. Infrared sensing is the use of all objects above the absolute zero temperature to announce the infrared radiation energy to the surrounding space. The infrared radiation energy of the object and its distribution according to the wavelength have very close contact with its surface temperature. Thus, by measuring the infrared energy radiated from the object itself, its surface temperature can be accurately determined. Infrared sensing error measurement is therefore very safe. The disadvantage is that it is greatly affected by the emissivity, environment and aerosol of the object during temperature measurement, and the anti-interference is poor.
Temperature measurement. The thermocouple transmission signal requires a special compensation line, and the transmission distance should not be too long. It is not suitable for the actual situation where the cable head has a wide distribution. The thermistor is generally a platinum resistor. Generally, a three-wire transmission is required, and the bridge output is balanced. The transmission distance should not be too long, and the ability to resist interference is poor.
Integrated circuit temperature measurement. There are many types of integrated circuit type temperature measuring components. The current output type components have large internal resistance and are suitable for long-distance transmission. Generally, they are small in size, and can be sealed at the measured point by using a thermal conductive silicone with anti-corrosion, moisture-proof and high-temperature resistance. The external wiring is led out by two lines to transmit data, but it is greatly affected by electromagnetic force at the measured point.
Fiber distributed temperature monitoring. The fiber distributed temperature measurement system is a relatively advanced system. The measurement of the temperature is accomplished by the effect of the laser pulse transmitted in the fiber to the Raman scattering temperature effect. The latest fiber-optic distributed temperature monitoring system allows the fiber loop length to reach 12 km and the measurement accuracy to ±1 °C. The advantage of using the fiber distributed temperature monitoring system is that it can accurately position the hand-held orientation along the plastic cable connector, and can flash and record the temperature change curve track, which can flash the position of the hand on the line. Such a system requires the ability to determine the location of the hand in the device, but relying on pre-made monitoring equipment and optical / thermal data processing, this not only increases the additional equipment funding, the new equipment also faces the problem of patch protection.