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Time response is measured by immersing the sensor in water moving at 1 m/s (3.3 ft/s) with a 63.2% step change. Size A standard RTD sheath is 3.175 to 6.35 mm (0.1250 to 0.2500 in) in diameter; sheath diameters for thermocouples can be less than 1.6 mm (0.063 in). Accuracy and stability requirements
Figure 2: [8] Working principle of a thermal laser sensor (Adapted from figure 3 with permission) As shown in Fig 2, a thermopile laser sensor consists of several thermocouples connected in series with one junction type (hot junction at temperature T 1) being exposed to an absorption area and the other junction type (cold junction at temperature T 2) being exposed to a heat sink.
When used in conjunction with a monitoring relay they provide overtemperature protection to prevent insulation damage. The equipment manufacturer selects a thermistor with a highly non-linear response curve where resistance increases dramatically at the maximum allowable winding temperature, causing the relay to operate.
The two top thermocouple junctions are at temperature T 1 while the two bottom thermocouple junctions are at temperature T 2. The output voltage from the thermopile, ΔV , is directly proportional to the temperature differential, ΔT or T 1 - T 2 , across the thermal resistance layer and number of thermocouple junction pairs.
The thermowell protects the instrument from the pressure, flow-induced forces, and chemical effects of the process fluid. Typically a thermowell is made from metal bar stock. The end of the thermowell may be of reduced diameter (as is the case with a tapered or stepped-shank thermowell) to improve the speed of response.
A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction.A thermocouple produces a temperature-dependent voltage as a result of the Seebeck effect, and this voltage can be interpreted to measure temperature.
Sensor inputs can be accelerometer, thermocouple, thermistor, resistance thermometer, strain gauge or bridge, and LVDT or RVDT. Specialized inputs include encoder, counter or tachometer, timer or clock, relay or switch, and other specialized inputs. Outputs for signal conditioning equipment can be voltage, current, frequency, timer or counter ...
Conceptual schematic of a bolometer.Power, P, from an incident signal is absorbed and heats up a thermal mass with heat capacity, C, and temperature, T.The thermal mass is connected to a reservoir of constant temperature through a link with thermal conductance, G.