FAQ about Compensation Cables and RTD Cables for Temperature Sensors

In this section, we answer the most common questions about thermocouple compensation cables and RTD cables for PT100/PT1000 probes, covering their function, types, materials, applications, and selection criteria in demanding industrial environments. The content is geared towards engineers, maintenance personnel, and process managers who need to ensure the reliability of temperature measurements from the sensor to the control system.

What is a compensation cable?

A compensation cable is a specific cable designed to extend the signal generated by a thermocouple from the point of measurement to the reading, control or regulation equipment (PLC, recorder, regulator, etc.), without introducing significant errors in the measurement.

Unlike a conventional electrical cable, the compensation cable is made of special alloys that reproduce the thermoelectric behavior of the thermocouple within a limited temperature range, usually corresponding to the ambient temperature of the cable run.

Its use is necessary when:

The thermocouple cannot be connected directly to the control equipment.
The instrument is located away from the point of measurement.
The temperature of the cable's environment is moderate and stable.

What are compensation cables used for?

Compensating cables are used for:

Transmit the thermocouple signal without altering the measurement
Keep the control instrument away from high-temperature areas
Facilitating complex industrial installations
Reduce costs compared to using a complete thermocouple cable

They are essential in industrial temperature measurement installations.

What is the difference between a compensating cable and an extension cable?

Compensation cable: manufactured with alloys different from the thermocouple, but with equivalent thermoelectric behavior in a limited temperature range.
Extension cable: made with the same materials as the thermocouple, suitable for wider temperature ranges.

The choice depends on the ambient temperature of the cable run and the accuracy requirements.

What types of compensation cables are there?

Compensation cables are manufactured according to the type of thermocouple they are associated with; among the most common are:

Compensating cable for type K thermocouple
Compensating cable for type J thermocouple
Type T thermocouple compensation cable
Compensating cable for type N thermocouple
Compensation cable for noble type S and R thermocouples (in specific configurations)

Each type has standardized polarity and colors, which must be respected to avoid measurement errors.

What type of insulation can compensation cables have?

The cable insulation is selected based on the working environment. The most common types are:

PVC / PVC – general use
Silicone – greater heat resistance
PTFE (Teflon) – high temperatures and aggressive environments
Fiberglass – high temperature applications
Fiber metal mesh – additional mechanical and thermal protection

A poor choice of insulation can lead to premature cable failure.

What is an RTD cable?

An RTD cable is the cable used to connect PT100 or PT1000 temperature probes. Unlike thermocouples, RTD measurement is based on the variation of electrical resistance, so the cable plays a key role in the accuracy of the system.

What types of RTD cables are there?

RTD cables differ primarily in the number of conductors:

2 wires – simple applications, lower precision
3 wires – partial compensation of cable resistance (very common in industry)
4 wires – maximum precision, eliminates cable interference

The choice depends on the level of precision required and the control system.

What materials are used in RTD cables?

RTD cables are typically manufactured with:

Copper conductors
PVC, silicone, PTFE or fiber insulation
Optionally with a screen or metal mesh to reduce interference

Correct selection ensures stability and repeatability of the measurement.

How to choose a suitable compensation cable or RTD cable?

To select the correct cable, you must take into account:

Sensor type (thermocouple or PT100 / PT1000)
cable ambient temperature
Distance between sensor and instrument
Presence of electrical interference
Mechanical conditions (vibration, abrasion)

Technical advice prevents reading errors and breakdowns.

Do you have compensation cables and RTD cables in stock?

Yes. Payne Supplies has thermocouple compensation cables and RTD cables in stock, in various configurations and insulations, for quick delivery in industrial applications.

The distribution is for Jemar Thermometry and its temperature measurement solutions.

Can custom-made cables be supplied?

Yes. Cables can be supplied:

Per meter
In specific lengths
With connectors mounted
Integrated into PT100 thermocouple assemblies

This facilitates installation and reduces assembly times at the plant.

In what industrial applications are these cables used?

Compensation cables and RTDs are used in:

Industrial ovens
Iron and steel industry and metallurgy
Chemical industry
Feeding
Energy
Continuous thermal processes
Process automation and control

They are a critical element for the reliability of temperature measurement.