Thermocouple and compensating leads WATLOW
   
Why is this lead necessary..
 

Thermocouple leads are featured by the fact that they are made from identical material as that of the thermocouple itself. Therefore there are also types J, K,... Thanks to the aforementioned no other joint represents (e.g. clamps between thermocouple and sequential lead) new thermocouple. If we used a common conductor it would result in a joint of two different materials and it would give rise to another thermocouple that would generate voltage depending on the temperature of this joint. This voltage would be added to the voltage of the thermocouple itself, which would result in impairment and degradation of measured value.

Compensating leads are cheaper substitution of the thermocouple lead. The compensating leads are made from noble metals – the material, which is not identical with that of thermocouple metal. Despite these nonconformities the compensating leads maintain similar parameters as thermocouples do however it is valid only for temperatures up to 200°C (exceptionally up to the temperatures 260 °C ). For higher temperatures it is necessary to use thermocouple leads. These leads are divided as follows J, K,..
However for both leads applies as valid principle that the longer is the lead the higher level of error is brought into the sensor measurement, which means the error due to lead resistance (the sensor generates voltage levels represented by values of the order of a few tens mV
  • For the thermocouples of E, J, K, N, T, B, C, R and S types
  • Diameters of conductors 1.3, 0.8, 0.5, 0.3, 0.25 mm
  • Temperature resistance 100, 200, 260, 480, 700, 980, 1200 °C
  • Resistance to moisture, oils and other chemical substances
  • Solid wire, stranded wire – for both fixed and movable fit
  • Double insulation - selection of materials for every application
  • Electric shielding, twisting – increasing of resistance to interference
  • Stainless steel braid – the increase of mechanical resistance, food- processing industry
 
Basic types of thermocouple insulations and compensation leads:
Internal insulation
External insulation

Max. temperature

PVC
PVC
105 °C
FEP (fluoroplastic)
FEP
260 °C
TFE, fibreglass
ServTex
316 °C
TFE
TFE
316 °C
Fibreglass
ServTex
343 °C
Polyimide (sintered kapton)
Polyimide
427 °C
Fibreglass
Fibreglass
538 °C
Double fibreglass wrapping
Fibreglass
538 °C
High temperature fibreglass
High temperature fibreglass
871 °C
Silicone fibre
Silicone fibre
1093 °C
Ceramic fibre
Ceramic fibre
1427 °C
 
Types of leads being used most frequently, mostly available in stock
Designation
Type
Diameter
Type
Insulation
Temperature
Price per/m
J20-5-510
J
0.8mm
Compensation, solid wire, standard. accuracy
PVC/PVC
105°C
-
K20-5-510
K
0.8mm
Compensation solid wire, standard accuracy
PVC/PVC
105°C
-
S20-5-510
S
0.8mm
Compensation solid wire, standard. accuracy
PVC/PVC
105°C
-
J20-3-S-304
J
0.8mm
Thermocouple stranded conductor standard. accuracy metal braided screening
Glass fibre
538°C
-
K14-2-350
K
1.6mm
Thermocouple solid wire, increased accuracy
Ceramic fibre
1427°C
-
K20-3-S-304
K
0.8mm
Thermocouple stranded conductor, standard accuracy,metal braided screening
Glass fibre
538°C
-
 
With respect to large scope of assortment and big number of variations it is necessary to ask for particular price for particular leads by phone. In case of larger scope purchase the price is set on the basis of mutual agreement, i.e. on individual basis.
 
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