1. Safety notes¶
This section is intended for installers and service technicians. Follow all steps and local regulations. Work on electrical equipment may only be carried out by a qualified person.
Warning levels
Danger
A situation that will result in serious injury or death if not avoided.
Warning
A situation that may result in serious injury or significant material damage.
Caution
A situation that may lead to minor injury or damage.
Note
Important recommendation for reliable operation.
Tip
Useful information for easier operation of the device.
Important
Information that is important to remember.
1.1. General safety measures¶
Before carrying out any work, switch off the power supply and ensure it cannot be switched on accidentally.
Comply with applicable standards and regulations, as well as the manufacturer’s instructions for connection and commissioning.
Do not open the device. There are no user-serviceable parts inside.
If the device is visibly damaged or if liquid has entered it, do not use it.
1.2. Electrical safety¶
The DT240 is powered by an alternating voltage within the range of 100–250 V, 50/60 Hz. Use protective switches/fuses with appropriate characteristics.
Main relay: voltage-free changeover contact, switching capacity up to 25 A / 250 V~. Ensure external power supply for the loads and appropriate circuit protection.
Auxiliary (semiconductor) relay: up to 1 A / 250 V~. Do not pass higher loads through it; use it for signalling or control.
Connect the protective conductor (PE) of the load directly to the PE of the power supply.
Cable cross-section: up to 2.5 mm² for power supply and sensor terminals; up to 4 mm² for main relay terminals.
Note
The NTC sensor circuit is galvanically isolated. Nevertheless, laying and connecting must be carried out in accordance with professional standards.
1.3. Installation and wiring¶
The device is 2 modules wide (~36 mm) for a 35 mm DIN rail. Ensure a flat and secure mounting surface.
For cooling, leave a clearance of 10–15 mm to adjacent equipment, especially under higher relay loads.
Finish cables with insulated ferrules; avoid soldered ends in terminals. Check tightening after 24 hours of operation.
1.4. Terminals – overview¶
Terminals |
Purpose / Note |
|---|---|
4 (L), 5 (N) |
Device power supply 100–250 V~ |
6, 7 |
NTC sensor (order and/or colour of wires is not critical) |
8, 9 |
Auxiliary electronic relay (1 A / 250 V~), most commonly used for alarm |
1, 2, 3 |
Main relay (switching, voltage-free). 3 = L input, 2 = L output to load |
1.5. Temperature sensor – installation and cable routing¶
An NTC resistor is used as the temperature sensor. This means that the sensor’s resistance decreases as the sensor temperature rises, and conversely, increases as the sensor temperature falls.
Various NTC temperature sensor resistances are supported; check and correctly select the type in the device settings.
The sensor cable may be laid near power cables; due to digital filtering, lengths of up to ~100 m are possible. However, for extending the temperature sensor cable, a cable with twisted wire pairs and mechanical protection where necessary is recommended.
In humid or cold environments, protect the probe from condensation and moisture (appropriate sheath/probe).
1.6. Parameter protection and operational verification¶
Set the minimum and maximum permitted temperature limits in accordance with the process being regulated.
Verify that the correct operating mode (Heating/Cooling) and differential are selected.
Enable the turn-on delay if necessary to avoid unwanted short-term activations.
After commissioning, perform a function test: vary the temperature above and below the set value and observe the relay response.
1.7. Alarm and auxiliary output¶
Activate alarms for sensor open-circuit/short-circuit and low/high temperature as required.
Define the alarm sources and what is activated (internal buzzer and/or electronic relay).
If heating/cooling process safety is imperative, do not use alarms as the sole protection against overheating/freezing. Also use separate limiters/protective thermostats in accordance with process standards.
If the electronic relay is used for alarms, it cannot be used simultaneously as an auxiliary output in thermostat mode.
Caution
The device uses a triac as the alarm output. Therefore, only alternating voltages may be connected to the alarm terminals (8-input and 9-output).
If a DC voltage greater than 5V is connected to terminals 8 (input) and 9 (output), the alarm output (triac) will not be able to switch off once activated until the voltage on the input terminal (8) is removed.
1.8. Prevention of unauthorised changes¶
Enable locking and set a password; consider automatic locking after a period of inactivity.
Use the Status bar to view output status, alarms, and the set temperature.
1.9. Maintenance and periodic checks¶
Periodically check terminal tightness, signs of overheating (discolouration, odour), and the condition of cables and sensors.
Check the alarm function. Test at least after major servicing or changes to settings.
Ensure adequate airflow around the device; clean dust with a dry cloth. Do not use solvents.
1.10. Disposal¶
Dispose of electronic equipment in accordance with local regulations (e-waste). Do not dispose of with household waste.
Note
These guidelines supplement but do not replace local regulations. Always adapt protective elements (fuses/RCBOs, cable cross-sections, sensor type) to the actual installation conditions.