4. Technical specifications¶

Parameter	Value / Description
Name	DT240
Functionality	multifunctional thermostat
Temperature range	from -55 °C to +255 °C
Hysteresis	from 0.1 °C to 10 °C
Accuracy	± 1 °C
Mounting method	35 mm DIN rail mount (according to EN 60715)
Supply voltage	100-250 V AC, 50/60 Hz
Power supply terminals	terminals 4-5
Type of internal power supply	safety transformer galvanically isolated
Own power consumption	< 2 VA
Sensor type	NTC resistor 10/12/15/16.7/33/47/50/100 kΩ
Sensor terminals	terminals 6-7
Operating Modes	Thermostatic (heating/cooling) Manual Timed
Dimensions	D=91mm, W=36mm, H=59mm ( 2 DIN modules )
Mass	126 g
Output	relay contacts
Main output terminals	Electromechanical relay
Main output terminals	1 - normally closed (NC) contact (dry) 2 - normally open (NO) contact (dry)
Maximum permissible voltage and current for the electromechanical relay	25 A / \(\sim\ \)250 V / cosφ ≥ 0.8, 25 A / 30 V
Mechanical endurance of contacts	10⁷ switching operations
Electrical endurance of contacts	10⁵ switching operations
Alarm/auxiliary output terminals	terminals 8-9
Type of alarm / auxiliary output	Electronic relay / triac (only AC voltage connections permitted) (max. 1 A, 250 Vac)
Permitted ambient operating temperature	-20 °C to +55 °C
Protection rating	IP 40 control panel IP 20 terminal blocks
Overvoltage category	III
Degree of pollution	2
Cross-section of connection cables	Relay terminals ≤ 4 mm² Other terminals ≤ 2.5 mm²
In accordance with the standard	IEC/EN 60730-2-9

4.1. Device dimensions¶

4.2. Wiring diagram¶

On the side of the thermostat housing, a block diagram of the thermostat connections is printed, providing sufficient information for quick and correct wiring and operation of the thermostat.

The thermostat must be supplied with power, connecting the live conductor to terminal number 4 and the neutral conductor to terminal number 5. The thermostat operates on alternating voltage, which can vary from 100 V to 250 V, while consuming a maximum of 2 VA itself.

Note

Terminals 1, 2, and 3 accept wires up to 4 mm².

All other terminals accept wires up to 2.5 mm².

An NTC temperature sensor is connected to terminals 6 and 7; neither the order nor the colour of the wires matters. Compatible NTC sensors are: 10, 12, 15, 16.7, 33, 47, 50, and 100 kΩ / 25°C. The factory setting is a 10 kΩ NTC sensor. If using a different type of sensor, you must select the appropriate option in the settings (Settings → Temperature → Sensor Type).

Terminals 8 and 9 belong to the thermostat’s auxiliary output. This is a voltage-free output of an electronic load relay rated up to 1 A exclusively for alternating current. Depending on the thermostat settings, it can serve as an auxiliary output for control, remote monitoring, or as an alarm output signalling a fault in the regulated process.

The electronic relay output, on terminals 8 and 9, is used to open or close a circuit via this connection. Using the auxiliary output is not always necessary, nor is connecting to it.

Caution

Only alternating voltages may be connected to the alarm terminals (8 and 9).

Finally, there are terminals 1, 2, and 3. These are terminals for accepting conductors with a cross-section up to 4 mm², which belong to the switching contact of the main electromechanical output relay. The relay’s switching capacity is 25 A at an alternating voltage of 250 V.

Note

The switching contact is voltage-free, meaning it receives no power supply from the thermostat itself. To open or close the circuit of the connected load via its switching action, an external power supply must be provided.

When controlling a heating process, the live conductor L is brought to terminal 3, and when the condition for heating operation is met, the switching contact connects to terminal 2. Therefore, the live conductor powering the load is connected to terminal 2, while the neutral N conductor of the load supply goes directly to the neutral conductor of the power source. Similarly, the protective conductor (PE) of the load is connected directly to the protective conductor of the power source without involving the thermostat.

Warning

For safety reasons, appropriate fuses or Residual Current Circuit Breaker with Overcurrent protection switches (RCBOs) must be installed in the power circuits of both the thermostat and the load.

When installing the DT240 thermostat on a DIN rail, it is advisable—and mandatory when the current load on the main output relay exceeds 16 A—to leave a gap of 10–15 mm relative to adjacent equipment to ensure better cooling.