A thermal converter is a device that is designed to measure temperature. The principle of operation of this device is built on the electrical resistance of metals and individual alloys. The main element of thermal converters is considered to be semiconductors. Some experts call them thermistors.
If we consider a standard thermal converter, then it has only one resistor. It is made entirely of metal wire. In some cases, it can be made of film. Platinum thermal converters are today considered the most common. This is due to the fact that this metal has a good dependence of resistance on temperature. Also, platinum has a high oxidation resistance. Reproducibility thermal converters of this type show a fairly high.
Modern models are made of high purity platinum. In this case, the temperature coefficient of the metal is at the level of 0.003. However, there are many copper and nickel devices on the market. All technical requirements are dictated by GOST. In frequency, this system of measurement uniformity gives temperature ranges, accuracy classes and standard dependencies of resistances.
Two-wire modifications
To work in a gaseous environment, a two-wire resistance thermoconverter is used. The circuit of his device is quite simple. In the upper part there is a sensitive element with a conductor. It connects to the fitting. In the lower part of the case there are clips and a cable. The error at subzero temperatures for models does not exceed 0.3 degrees.
Tolerance according to GOST 6651, these modifications have series A. If we consider the PT100 resistance thermoconverter, then the minimum temperature parameter of the device lies in the region of -60 degrees. If we talk about the design features of the models, it is important to note that they are made with sealant. There are usually two conclusions. The clamps are mounted directly on the front of the case.
Three-wire thermal converters
Three-wire resistance thermoconverter is excellent for liquid media. However, the minimum temperature parameter for models averages -30 degrees. It is also important to note that the error in an aggressive environment can reach 0.45 degrees. There are two conclusions in devices of this type. Directly admitted according to GOST 6651 there is a series A. The indicator of the minimum allowable temperature fluctuates around 230 degrees.
If we consider the thermal resistance converter TC 1088, then the length of its mounting part reaches 100 mm. If we talk about modifications with a terminal head, then they have three outputs. Protective fittings are used with the marking 12X. The thermal inertia index can reach up to 10 s. In turn, the maximum nominal pressure parameter is on average 6.2 Ru. Calibration of resistance thermal converters is carried out using temperature calibrators.
Four wire devices
The four-wire resistance thermoconverter is designed to measure temperature in a liquid medium. If we talk about the error of resistance, then this parameter is able to reach 0.03 Ohms. In this case, the sensitivity of the instruments averages 33 microns. If we talk about modifications with tolerance A, then the minimum temperature at which they are able to work is 30 degrees below zero. The nominal static characteristic of devices reaches 100 MP. Protective fittings in many versions are used with the marking 12X.
If we consider the thermal converter of resistance DTS 105, then the maximum temperature is 230 degrees. The permissible deviation limit is not more than 0.15 T. It is also important to note that devices of this type are available with terminal heads. The insulation used in them is only ceramic. In this case, the clamps are installed in front of the housing. If we talk about sensitivity, then these devices have a maximum of 32 microns.
Platinum modifications
The platinum resistance thermoconverter (KTSP) is capable of boasting an excellent indicator of thermal inertia. However, in this case, it is important to take into account the model tolerance according to GOST 6651. If we consider modifications to the A series, then in this situation the nominal static characteristic of the devices does not exceed 50 P. The inertia index in turn is 10 s.
The maximum temperature resistance thermoconverter (platinum) series A is able to tolerate 240 degrees. Protective fittings for models are most often used with the marking 12X. If we consider the resistance thermoconverter (GOST 6651) with the tolerance of the B series, then it has a parameter of the nominal static characteristic equal to 100 P. The inertia index in turn reaches 25 s.
Copper devices and their parameters
Resistance thermocouple (copper) is only suitable for gaseous media. In terms of parameter errors, the modifications are quite different. First of all, it is necessary to consider thermal converters with a tolerance of series A. They are used at a temperature of even -50 degrees. However, their sensitivity is not very good. This parameter on average does not exceed 34 microns. All this suggests that at a temperature of less than 0 degrees, the error on average is 0.5 degrees.
The thermal inertia index, in turn, reaches 10 s. In this case, the maximum possible temperature for the models is 230 degrees. The permissible deviation limit in this case reaches 0.12 T. If we talk about design features, then there are no terminal heads for models of this type. Sealant is used with powder in many configurations. Directly insulators are often used silicon type. If we consider thermal converters with a series B tolerance, then they have a sensitivity of 40 microns. All this suggests that at temperatures less than 0 degrees, the error can reach 0.45 degrees.
Considering the design features of the modifications, it is important to note that many models are equipped with terminal boxes. In this case, the sealant is standardly used with powder. The clamps are mounted directly on the front of the case. Protective fittings are most often used with the marking 15X.
Nickel devices
Nickel resistance thermocouple today is highly sought after. This is primarily due to the fact that the models have a high parameter of permissible marginal deviations. Also, many modifications are able to boast excellent conductivity. If we consider devices with a tolerance according to GOST 6651 series A, it is important to mention that the error parameter for them does not exceed 0.23 degrees. The permissible deviation limit, in turn, is at the level of 0.12 T.
The nominal static characteristic of the models is on average 30 P. However, it is also important to consider modifications with access to the B series. They have protected cases, and they withstand a limit temperature of 230 degrees. The length of the mounting part of the models on average does not exceed 100 mm. If we talk about the main parameters, it is important to mention that the sensitivity of devices on average is 35 microns. The maximum nominal pressure of the system is maintained at 6.6 Ru. The thermal inertia parameter never exceeds 13 s.
High temperature models
A high temperature resistance thermoconverter can be produced with different tolerances. Depending on it, the error parameter will change, and other parameters of the device. If we talk about access to Series A, then thermal converters of this type have a high nominal pressure. Minimum devices can be used at a temperature of -30 degrees. The housings of these devices are well protected from dust. The permissible error margin of the device does not exceed 0.12 T. The sensitivity, in turn, is 33 microns.
The nominal static characteristic of thermal converters is 40 P. However, it is also important to consider modifications with access of series B. According to GOST 6651, the sensitivity index for them must be at least 20 microns. At temperatures above 0 degrees, the error rate of devices does not exceed 0.44 degrees.
If we talk about the design features of the models, then their clamps are installed in the front of the case. Directly the head is located at the top of the device. There are two conclusions in total. It is also important to mention that thermal converters of this type are equipped with ceramic thermal insulation.
Features of submersible modifications
The immersion thermocouple is necessarily equipped with a terminal box. Cable cores in many models are hidden with a sheath. The clamps in this case are located in the lower part of the housing. Directly, the product parameters are closely related to the access series according to GOST 6651. However, it should immediately be noted that the immersion thermal converter can be operated in aggressive environments. If we consider modifications with a series A tolerance, then the sensitivity of the device in this case does not exceed 42 microns. The error in this case is 0.02 degrees. However, it is important to consider that the thermal inertia index will never exceed 10 s.
The nominal static characteristic of submersible devices is 50 P in accordance with GOST 6651. There are two conclusions in total of the presented thermal converters. It is also important to consider models with access of series B. First of all, a high sensitivity parameter deserves attention - at the level of 30 microns. All this makes it possible to reduce the accuracy of the device to 0.023 degrees. The maximum temperature of the medium in this case should not exceed 240 degrees. The length of the mounting part for models averages 85 mm. Directly protective fittings are applied with marking 12X. The thermal inertia index of thermal converters does not exceed 3 s.
Explosion proof models
A thermal converter of this type is designed to operate in a gaseous environment. In this case, the terminal heads are used with a fitting. The maximum temperature devices can withstand at the level of 250 degrees. The thermal inertia index is closely related to the access series of the device. However, it is important to note that all models withstand maximum nominal pressure at a level of 6.7 Ru. If we consider devices with Series A access, it is important to mention that the error at temperatures above 0 degrees is 0.035 degrees.
The terminal head in these configurations is installed in the upper part of the housing. Directly the nominal static characteristic of thermal converters does not exceed 60 P. The permissible deviation limit of the device is on average 0.20 T. It is also important to consider thermal converters with access of series B. They have three conclusions. Direct insulation is applied ceramic type. As mentioned earlier, the maximum nominal pressure is maintained at the level of 6.7 Ru. Minimum models can be operated at a temperature of -30 degrees.
The sensitivity of the devices does not exceed 40 microns. The error at temperatures above 0 degrees is approximately 0.040 degrees. The nominal static characteristic of the devices is 40 P. The mounting part of the models does not exceed 80 mm. The thermal inertia parameter in the devices is quite high. However, the permissible deviation limit is only 0.33 T.
Accuracy TSP-0196-01
The resistance thermoconverter TSP 0196-01 is designed for liquid media. According to GOST 6651, it has a tolerance of series B. The minimum temperature of the medium is -35 degrees. The nominal static characteristic of the device does not exceed 50 P. If we consider modifications with terminal boxes, then the length of the mounting part for them is 85 mm. Protective fittings for the model are used with the marking 13X. The thermal inertia of the device is at the level of 15 s. In turn, the maximum temperature is 240 degrees.
The permissible deviation limit on average does not exceed 0.15 T. At temperatures above 0 degrees, the resistance thermoconverter TSP 0196-01 gives an error of 0.033 degrees. The terminal box configuration is equipped with three pins. In this case, the sensing element is located in front of the housing. Direct insulation is provided by the manufacturer of the ceramic type. The sealant, in turn, is applied with the powder. Thus, the case is quite heavily protected, and problems with metal oxidation in this model are rare.
Model TSM-0196-02
The resistance thermoconverter TCM 0196-02 is designed to work in a liquid medium. It differs in good conductivity, and a high parameter of maximum temperature. However, in the first place, it should be noted that it has a series A tolerance according to GOST 6651. In this case, the minimum temperature indicator is -50 degrees.
For laboratory research, the presented instance is used quite often. At temperatures above 0 degrees, its error is not more than 0.045 degrees. The nominal static characteristic of the device is about 55 P. The mounting part of this model is 85 mm. Directly protected fittings are used with the marking 12X.
The maximum temperature parameter is at around 250 degrees. There is no terminal box in this configuration. The manufacturer has two conclusions. Metal oxidation problems are rare, since sealing is used with powder. The insulation in this case is reliable.
Thermal converter TSP-0196-06
A thermal converter of this type is quite in demand in the production of fusible metals. In this case, the protective fittings are provided for 15X. Directly admitted according to GOST 6651, the model has a series B. The minimum temperature of the medium is -30 degrees. High sensitivity parameter deserves special attention. However, it should be noted that at temperatures above 0 degrees, the error of the thermal converter is 0.022 degrees.
The length of the mounting part of the model is only 60 mm. The thermal inertia index is at around 12 s. The maximum permissible ambient temperature at which the device can be used is 240 degrees. A terminal head is provided for this thermal converter.