Cables and connectors
General abot cables and connectors
Cables and connectors are made of special materials for thermocouple sensors. The materials are available as equal to the thermocouple in question and then as thermocouple wire (K) or connection line (KX).
For noble thermocouples, eg type R and S, genuine materials are too expensive to use so you have found common, inexpensive wire combinations that have similar properties to the thermocouple in question at low temperatures (0 - 100/200 ºC).
These replacement materials are then called compensation lines and are denoted, for example, by SCA, SCB, where S is the type of thermocouple, and C stands for compensation / replacement and finally A and B are different grades with different maximum temperature and laying temperature.
Similar divisions may apply to contacts and in some cases terminals.
Thermocouple wire fulfills the requirements on thermocouple material according to the IEC 60584-1. Often the properties of the insulation jacket limits the environmental temperature of the wire. See the data sheet of each product.
Extension cable fulfills the requirements of thermocouple material according to the IEC 60584-1 within a limited temperature range, -25 to 200 °C. Insulation jacket design may limit the environmental temperature further. As an example extension wire with PVC-jacket is limited to 90 °C while the naked wire can be used within the entire range -25 to 200 °C.
Compensation cable is not made of the genuine thermocouple material. The use of this cable is still more restricted in environmental temperature, typically 0 -100 °C. Today it is mostly used as extension cable for the expensive noble metals thermocouples like the types S and R. For type B plain copper wire can be used as temperatures below 500 °C practically do not generate any output signal. For both categories see Tolerances for extension and compensating cables according to IEC 60584-3
Extension cable (Pt100)
The number of leads in the cable is crucial for the function. Read more about 2-, 3- and 4-wire configurated instrumentation in the link The effect of
2-, 3- and 4-wire connection of Pt100-sensors.
Metal sheathed cable
The best property of metal-oxide insulated and metal sheathed (MIMS) cable is its ability to withstand moist, high temperature and mechanical stress. It behaves plastically and can be bent with some limitation. It is frequently used as probes for thermocouples and Pt100 sensors.
Thermocouples can be provided with different conectors for the output signal. There are mountable connectors of both standard and miniature size. There are also molded connectors fixedly connected to the sensor or cable.
Use connectors that are compensated for thermocouples for each type. In daily speech, the word compensated connector is generally used for all thermocouple connectors, however similar to connection cables for thermocouples, variants between thermocouple materials that meet the requirements for IEC 60584 with laying temperature within -25 to +200 ° C and contacts with compensated / alternative material also appear in the contact material.
Thermocouple connectors with compensated material do not consist of genuine thermocouple material and therefore function with higher tolerance. Today, compensation materials are most commonly used as replacement materials for the precious metal thermocouples R, S and B. Type B connectors use copper as a splicing material since type B does not generate any output signal up to 200 ° C.
The pins on thermocouple contacts are unique to prevent reversal of polarity.
Panels are practical to use at e. g. test cells where many thermocouples have to be available with great flexibility. Pentronic has a standard programme of panels which can be mounted in order to cover cut outs in instrumentation panels or lids of boxes. Besides we manufacture panels after customers drawings or sketches. Please contact us for more information.
Panel jacks of different kinds are available covering most instrumentation needs.
Terminal heads are normally used to connect the sensor signal to a measuring system at processes containing pipes and tanks. Such sensors are comparatively big and the terminal head protects the signal connection from dust, chemicals and other environments depending on material and design.
Moreover it has inside space to allow e.g. a 4-20 mA transmitter to be mounted or just a terminal block. Pentronic offers an extra option by supplying replacable measuring inserts with long connection wires to allow the customer to mount a transmitter or a terminal block at a later time when the final purpose of a spare part sensor is known.