JUMO exTHERM-DR Two-State Controller with Ex ia Input

DIN-rail two-state controller with intrinsically safe measurement input

The JUMO exTHERM-DR (type 701055) is a two-state controller for heating or cooling applications. Its intrinsically safe Ex (ia) measurement input allows direct connection of correspondingly type-tested probes, so a separate barrier is no longer required. The controller itself sits on a DIN rail outside the hazardous area.

Besides the relay output K1 for the controller function, a second relay output K2 signals when limit values are exceeded or not reached. As an alternative, a binary 0/10 V signal can drive a solid-state relay for control or limit signaling, and the standard analog output delivers the measured value or the setpoint.

The backlit LCD with 96 x 64 pixels shows plain text for measured value, setpoint and limit value. Configuration can be done on the keys or with the setup program through the standard USB interface on the front.

The device has a one-input design with a universal analog input, one analog output, one binary input and two relays, and it is supplied from either a mains or a low-voltage source, so it fits most cabinet supplies.

Technical specifications

Terminals, approvals and sensor choice

Devices with blue terminals carry the intrinsically safe marking with the Ex ia sensor input, while devices with black terminals carry the Ex e and Ex t marking. Check the terminal color and the certificate number for the version you order, because the sensor must be type tested for the intended zone.

A line resistance of up to 15 Ohm in two-wire and 30 Ohm in three-wire circuits is permitted for RTD probes. The controller reports overrange, probe break and short circuit on the display, and relay K1 is switched inactive on probe break.

The test voltage between inputs and outputs against the supply is 3.7 kV, and clearances of 6 mm and creepage distances of 8 mm apply between mains and electronics, to DIN EN 60730-1.

The measured value or the setpoint can be output on the standard analog output, and the analog output can instead be configured as a logic output of 0/10 V for control of a solid-state relay. Contact ratings of the relays are 3 A at AC 230 V resistive or DC 30 V, with a minimum current of 100 mA at DC 12 V.

The data sheet gives accuracy figures of 0.1 percent for Pt100 and Pt1000 in the measuring range, 0.4 percent for thermocouples and 0.2 percent for the 4 to 20 mA input, plus a cold junction accuracy of +/-1 K with an internal Pt100.

Where it is used

Typical uses are thermostat control of heated tanks, pipe tracing and process vessels where the sensor sits in an explosive atmosphere but the controller can stay in a safe control room or cabinet. The 0/10 V logic output allows a solid-state relay to switch the heater.

The second relay can be configured as a limit output for an alarm. Note that this controller provides an alarm function and is not a certified safety temperature limiter; use a limiter such as the exTHERM-AT STB where a safety function is required.

Mount the controller vertically on the DIN rail, keep the ambient temperature between 0 and +55 °C, and route intrinsically safe wiring separately from other cables according to the plant rules. The configuration can be saved and loaded with the setup program.

Keep the setup program file for each controller. It documents the sensor type, setpoint, limit value and output scaling, and it allows a replacement controller to be configured exactly like the unit it replaces.

Documents and quotation

For engineering details, open the attached PDF (JUMO exTHERM-DR data sheet 701055 (EN, 13 pages)). When you are ready to buy, submit the order code and project requirements through the request form, and our team will confirm what can be supplied and when. Browse the category Controllers & Data Acquisition for alternatives.