RTD Cables and Connectors

Contents

1. Cable Types and Temperature Ratings
2. Importance of Extension Cables in RTD Measurement
3. RTD Connectors

Interconnection cables for RTD assemblies come in a variety of forms, typically adhering to the IEC 60751 international color-coding standard to ensure consistency and reliability. The most common cable type features 2, 3, 4 or 6 cores of insulated, stranded, silver-plated copper conductors. These wires are often interwoven and finished with a braided screen and outer protective sheath. Depending on the application, individual cables or multi-core options such as two, four, and six-core cables are also available.

Cable Types and Temperature Ratings

• PVC Insulated Cables:
  These extension cables feature PVC insulation and sheathing with a tinned copper braid for screening. They typically support temperatures up to about 105°C, making them suitable for general-purpose industrial environments.
• PFA Insulated Cables:
  Featuring PFA core insulation and sheathing along with nickel-plated copper braiding, these cables can withstand temperatures up to 260°C continuously, and up to 300°C for short periods. This makes them ideal for more demanding thermal environments.
• Fibreglass Insulated Cables:
  These high-performance cables have fiberglass insulation coated with varnish and stainless steel braiding for protection. Rated up to 480°C, they are used in the most extreme temperature environments.

Importance of Extension Cables in RTD Measurement

While extension cables play a critical role in thermocouple temperature measurement due to thermoelectric effects, their role in RTD systems is somewhat less critical but still essential. The key function of RTD extension leads is to transmit low-level resistance signals with minimal loss and to shield them from interference caused by external electrical noise, such as contactor operation.

RTD Connectors

Connectors for RTDs share similar requirements and designs to those used in thermocouple systems. The primary focus is on ensuring high-integrity, low-resistance connections that do not introduce additional contact resistance or signal degradation.

For best results, always use high-quality RTD connectors matched to the cable and assembly type. These connectors maintain signal accuracy and reliability throughout the measurement chain.

Further Reading

RTD vs Thermocouple – Choosing the Right Sensor
Explore the features and characteristics of thermocouples and RTDs

RTD Output Tables
View Resistance versus Temperature tables for all Pt100 sensors.

What are the RTD colour codes?
Explore RTD colour codes and wiring configurations.