Temperature transmitters and temperature sensors

In our temperature transmitters and temperature sensors, the electronics are already inside the sensor. Instead of putting together a sensor and a head-mounted transmitter separately, you get one device that measures, displays, linearizes and delivers a standardized signal. Available as a screw-in sensor, as a magnetic surface sensor and as a non-contact infrared version, with HART, wireless, and in ATEX and IECEx versions.

Temperature sensor and temperature transmitter in one device

Traditionally, an industrial temperature measurement consists of two parts: the sensor and a transmitter that sits in the terminal head or on the DIN rail. This works, but it has three drawbacks. You need two items that have to match each other, a connection between them, and with thermocouples the cold junction moves into the terminal head, where it is exposed to the ambient temperature.

With an integrated design, all of this is eliminated. The sensor already delivers a standardized, linearized signal; there is one item number, one installation and no interface where an error can creep in. For plant builders this means less engineering, for maintenance an easier replacement.

Three measuring principles

Resistance thermometers (Pt100, Pt1000) are the standard in industrial temperature measurement. They use the temperature dependence of the electrical resistance of platinum, are very accurate, stable over the long term and available in two-, three- or four-wire configuration. The right choice for most applications in HVAC and in machine and plant engineering.

Thermocouples are based on the Seebeck effect: two different metals generate a temperature-dependent voltage at their junction. They are robust, simple in design and cover a considerably wider range. Type K made of NiCr-Ni measures from -200 °C to about 1300 °C, depending on the version. Where it gets very hot or a fast response time matters, the thermocouple is the right choice.

Infrared sensors measure without contact via the emitted thermal radiation, up to 1000 °C. They make sense for moving parts, aggressive media, very fast processes, or anywhere a sensor cannot be introduced into the process. In the screw-in version, the sensor sits permanently in the process, pressure-tight and vibration-resistant.

Designs

Screw-in sensors are introduced directly into the pipe, vessel or apparatus via a process thread. This is the most accurate route because the sensor sits in the medium, but it requires an intervention in the process.

Magnetic surface sensors are placed on pipes, vessels or machine parts from the outside. This is the interesting option for retrofits: you get a measuring point without opening the system, without a shutdown and without a leakage risk. For bearing monitoring, existing pipework and temporary measurements, it is often the only practical route.

Modular compact sensors are suitable for confined installation situations and for series equipment in HVAC technology.

Features that make the difference

Display directly on the sensor. The value can be read on site, without a control room and without a measuring instrument. During commissioning and troubleshooting, this saves the walk.

Configurable limit contacts. The sensor switches by itself when a threshold is exceeded or undershot. This lets you set up an overtemperature alarm without the control system needing logic for it. If only switching is required and no measured value, a pure temperature switch connected directly to a digital input of the PLC is the less expensive solution.

HART configuration. Measuring range, damping and limit values can be set via the HART protocol on the existing 4…20 mA line, without additional wiring and during operation.

Wireless versions with remote configuration and evaluation software measure where no cable can reach or where cabling would be disproportionate. More on this under wireless measurement technology.

ATEX and IECEx versions for use in hazardous areas, for example in the chemical and petrochemical industries. Details on explosion protection.

How to choose the right sensor

• Measured object: liquid, gas or surface. This decides the design and whether the process is intervened in at all.
• Measuring range: every sensor is designed for a specific range. Outside it, the sensor not only measures inaccurately but is damaged. Pt100 covers the medium range, thermocouples the high temperatures.
• Accuracy and response time: both compete with robustness. A thin sensor responds quickly, a thick protection tube lasts longer. Clarify what your process really needs.
• Installation conditions: pressure, vibration, medium, cleaning, protection rating. A sensor for HVAC will not last in a chemical process.
• Communication: analog with 4…20 mA, with HART, wireless or as a switching contact, to suit your control system.

Tell us the medium, temperature range, installation situation and required signal, and our engineers will propose the right sensor.

Related options

If you already have sensors installed and only need the evaluation electronics, take a look at the OEM boards for temperature transmitters. If the aim is integration into your own device in series production, the overview of OEM boards is the right place to start.