In process plants and other industries it is impracticable and many a times impossible to have a cold junction at the end of thermocouple. It is therefore desirable to extend the couple to a reference point some considerable distance away. This can be achieved by the use of thermocouple extension or compensating cable.
Thermocouple extension wires and compensating cables have identical characteristics to their basic thermocouples in the restricted temperature span as is recommended in ANSI MC 96.1
With this range of cables the element conductors can be extended to a position where a stable temperature is maintained, transferring the effective cold junction to the remote end of the extension or compensating cable.
We offer prompt deliveries of thermocouple extension and compensating cables from a wide and expanding range of conductor combinations, configurations and insulating materials.
Each batch of cables is tested for thermo-emf performance as per ANSI MC 96.1 and relevant electrical properties as per Standards.
International conductor material specifications are met as are insulation color codes. Special customer requirements are created for, through our Research & Development wing.
SPECIFICATIONS:
- Conductors
16 Awg(1.29mm) standard for 1-pair and 20Awg (0.81mm) for multipair cables. Conductors such as 1.381 (1.5 mm2) or 18Awg (1.02) or stranded 7 * 0.3 (0.5mm2) also available on request.
Matched homogenous wire materials are used to obtain best results. - Insulation
Primarily insulation of extruded PVC, 85oC grade or 105oC grade is standard. Insulation such as LDPE, Fiber glass or asbestos braid is available as optional. - Pair
Insulated pair is twisted with a lay of 65 to 75mm. - Shield
Twisted pair or pair bundle is taped with Al-Mylar tape with 25% overlap, 100% shield, with 7 * 0.3mm dia, tinned copper wire in continuous contact, with AI side of tape. Cables with each pair shielded and overall pair bundle shielded also available. - Intermediate Sheath
Shielded pair or pair bundle is provided with soft extruded PVC, 85oC (105oC) grade. - Armor
Served, Annealed GI wire armor. - Jacked
Extruded PVC, 85oC or 105oC grade - Telephone Pair
Cables with six or more pairs are provided with, 2 Nos. * 20Awg solid conductors PVC insulated - Cable Characteristics
Cable with low L/R ratio, critical Capacitance and inductance values are designed to suit customer needs; to meet stringent requirement of secondary instrumentation.
Table 1: Maximum Inductance
| Cable Type | Conductor Material | Max Inductance Micro H/Mtrs | ||
| +ve | -ve | |||
| KX | Ni Cr | Ni Al | Extension Cable | 4.00 |
| WX | Fe | Cu Ni | Compensating Cable | 8.00 |
| VX(KXA) | Cu | Constantan | Compensating Cable | 1.20 |
| JX | Fe | Constantan | Extension Cable | 8.00 |
| TX | Cu | Constantan | Extension Cable | 1.20 |
| SX | Cu | Cu Ni | Compensating Cable | 1.20 |
| EX | Ni Cr | Constantan | Extension Cable | 4.00 |
| NX | Ni Cr | Cu Ni | Extension Cable | 4.00 |
| 1.00 | ||||
Table 2: Loop Resistance Thermocouple Extension/Compensating Cables
| Conductor Detail | Loop Resistance(ohms/mtr)+10%@20°C Cable Type |
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| AWG | Dia(mm) | Cross Sec.Area sqmm | KX | VX KX (A) | JX | TX | SX/RX | EX | XK |
| 16 | 1.29 | 1.31 | 0.76 | 0.39 | 0.46 | 0.39 | 0.104 | 0.97 | 0.97 |
| 18 | 1.02 | 0.823 | 1.21 | 0.62 | 0.76 | 0.62 | 0.169 | 1.52 | 1.52 |
| 20 | 0.81 | 0.50 | 1.98 | 0.97 | 1.20 | 0.97 | 0.266 | 2.50 | 2.50 |
Table 3: International Color Codes For Thermocouple Cable Insulation
| Conductor Combination | ANSI MC 96.1 AMERICAN | IS:8784 INDIAN | BS:1843 BRITISH | DIN 43710-4 GERMAN | NFE 18001 FRENCH |
| EXTENSION | |||||
| + Chromal – Alumel |
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| + Iron – Constantan |
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| + Copper – Constantan |
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| + Chromel – Constantan |
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| + Nicrosil – Nisil |
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| COMPENSATION | |||||
| + Copper – Constantan |
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| + Copper – Cupronic |
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