TC903, Schneider, Thermostat, [TC903-3A4LMA], Touch Button Thermostats - On/Off, Modbus, 4-pipe, 3 Fan, White

The Schneider Electric SpaceLogic TC903-3A4LMA is a digital thermostat designed for 4-pipe fan coil systems, supporting Modbus communication. The device operates on a supply voltage of 90–240 V AC 50/60 Hz and has a maximum power consumption of only 1 W. The thermostat detects room temperature with a measurement accuracy of ±1 °C using a 100 kOhm NTC thermistor sensor. The temperature setting range is 5–35 °C, and the operating ambient temperature is 0–50 °C, with relative humidity between %5–95. The backlit LCD screen displays ambient temperature (0–50 °C), time, day, temperature alarm, communication status, and current program information. In terms of output capacity, the device offers a 240 V AC 5 A relay output and a 240 V AC 2 A load output. Fan control is provided by a 3-stage speed control relay; actuator control is performed with a 2-position ON-OFF switch. Five mechanical buttons provide access to functions such as setpoint adjustment, fan control, mode selection, economizer, and low-temperature protection. Its physical dimensions are 86 x 86 x 40 mm (W x H x D), making it suitable for mounting in a standard BS wall box. Connections are made via rear screw terminals; it accepts 2 wires for 1.5 mm² or 1 wire for 2.5 mm². The white glass housing has an IP20 protection class, complies with EN/IEC 60730-1 and EN/IEC 60730-2-9 standards, and is CE certified. It is ideal for hotel, hospital, office building, and residential HVAC applications. It offers integration possibilities with building automation systems via Modbus protocol.