What is the difference between extension cable and compensating cable? - in Thermocouple Application
The process of connecting a thermocouple sensor to a measuring instrument through temperature measurement involves both extension cables together with compensating cables. The two devices differ both compositionally and in their uses.
| Aspect | Extension Cable | Compensating Cable |
|---|---|---|
| Purpose | Extends the thermocouple signal over long distances with minimal loss. | It serves as an economical solution to transmit thermocouple signals through different materials during transmission. |
| Material | The extension cables use identical material formats like the thermocouple devices (K-type extension cables include alloys that match K-type thermocouples). | Different alloy materials ensure proper function of thermoelectric properties across a specific temperature range. |
| Accuracy | Thermocouple accuracy reaches high levels when extension cables use similar materials to the thermocouple devices. | Less accurate than extension cables but suitable for moderate distances and lower temperatures. |
| Temperature Range | Thermocouple like performance exists between this device and the thermocouple at high temperatures. | Limited temperature range (typically up to 200°C). |
| Cost | Extension cables are more costly than other models as they use the same materials found in thermocouples. | The cable provides cost-effectiveness because it utilises low-cost materials as opposed to thermocouple components. |
| Identification | Denoted by an “X” in the cable type (e.g., KX for K-type extension cable). | The “C” identifier in the cable type (e.g., KC for K-type compensating cable) denotes this component. |
| Best Used For | This cable solution provides the best performance in accuracy-demanding systems needing long-distance signal transmission. | The technology works best when measurement accuracy requirements are flexible or when the distances between thermocouples remain short. |
You should employ extension cables for achieving precise measurements across extensive measurement ranges.
Compensating cables serve cost-effective temperature measurement needs when operating within their specified temperature range.
The production of thermocouple probes relies on thermocouple grade wire. The manufacturing process requires thermocouple grade wire for the point of junction as well as inside the stem sheath. The accuracy specification value for thermocouple grade wire surpasses that of extension grade wire.
Extension grade wire exists as an inexpensive product among lower quality wires. The control system and digital display use extension grade wire as an extension from thermocouple probes. The production of thermocouple probes with longer wires becomes less expensive through the utilization of extension grade wire. The extension wire serves different purposes from the thermocouple since it does not enter the manufacturing process directly nor functions as a critical component nor faces extreme temperatures within the system.
The sensor commonly resides inside a process pipe at a location that is remote from the control room area. The temperature reading requires running the wire through a long distance which leads back to the control room. The use of high-priced thermocouple grade wire serves no purpose for this application. Any wire in extension grade can fulfill this requirement.