Thermocouple Extension Cable JX-FB-FB-SS304-0.22R DIN43710 Standard Plywood Spool Package
TYPE J (Iron vs Constantan) is used in vacuum, oxidizing, inert or reducing atmospheres. Iron element oxidizes rapidly at temperatures exceeding 538°C, and therefore heavier gauge wire is recommended for longer life at these temperatures.
1. Chemical Composition
| Material | Chemical composition (%) |
| Ni | Cu | Si | Iron | Al |
| JP(Iron) | | | | 100 | |
| JN(Constantan) | 45 | 55 | | | |
2. Physical Properties and Mechnical Properties
| Material | Density(g/cm3) | Melting point(℃) | Tensile Strength(Mpa) | Volume resistivity(μΩ.cm) | Elongation rate (%) |
| JP(Iron) | 7.8 | 1402 | >240 | 12.0(20℃) | >20 |
| JN(Constantan) | 8.8 | 1220 | >390 | 49.0(20℃) | >25 |
3. EMF Value Range at Different Temperature
| Material | EMF value (μV) |
| 100℃ | 200℃ | 300℃ | 400℃ | 500℃ | 600℃ |
| JP-JN | 5187~5351 | 10696~10862 | 16244~16410 | 21760~21936 | 27281~27505 | 32962~33242 |
| EMF value Vs Pt(μV) | |
| 700℃ | 750℃ | 760℃ | 800℃ | 900℃ | 1000℃ | |
| 38958~39306 | 42089~42473 | 42725~43113 | | | | |
Thermocouple Cable Grade
A: Extension Grade Cable
Whose wire composition is totally as the same as the thermocouple wire, remarked by the letter“X”after the thermocouple symbol number, such as“KX”“JX”“TX”
B: Compensation Grade Cable
Whose wire composition is different from the thermocouple wire, but its wire electromotive force (EMF) value is the same as thermocouple wire only at 0-100℃ or 0-200℃. It remarked by the letter“C”after the thermocouple symbol number, such as“KC”“JC”“TC”
- For cost consideration, when the tested temperature under 200℃, compensation grade cable is preferred. But compensation grade cable will occur enormous tested temperature value deviation if the tested temperature above 200℃. The higher the tested temperature, the greater deviation be.
- For compensation grade cable, the max testing temperature is less than 200℃, the bigger the cable, the smaller the signal loss.
- Extension cable and compensation cable comparison:
| Performance | Extension Grade | Compensation Grade |
| Material | Same as thermocouple | Different from thermocouple |
| EMF Value Feature | Same as the thermocouple’s at certain temperature range | Same as the thermocouple’s |
| Deviation Curve | Nonlinear, varies with temperature | Linear |
| Working Temperature Range | Limited(usual at 100℃) | Unlimited(depend on insulation material temperature bearing) |
| Line Resistance | Low resistance | High resistance |
| Compensation Contact Interference | Different contactor material may cause interference | None |
| Accuracy | Low | High |
| Price | Low | High(about 1-2 times higher) |
For the extension/compensation cable, the basic structure is conductor and insulation.
To increase its temperature bearing ability and to install easily, jacket is applicable.
In the working environment, there are too much factors will interference the EMF signal, therefore shield layer is practical way to prevent the cable from interference caused by complex environment.
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