Temperature Controller FF RT-821B, DIN-rail, -4 to 5 °C range, 16 A, 1NO/1NC, 230 V AC, without sensor

FF RT-821B is a DIN-rail mounted temperature controller designed specifically for refrigeration applications. It offers precise temperature regulation within a cold-range setpoint from -4 to 5 °C and provides a single changeover output that can be configured as either normally open or normally closed. The controller operates from a 230 V AC supply and delivers switching capacity suitable for controlling compressors, fans or other refrigeration system components. The unit is supplied without a temperature probe so an external sensor must be selected separately to match the installation and accuracy requirements.

Advantages

The compact DIN-rail form factor enables straightforward installation in control cabinets and distribution panels. Adjustable setpoint and simple configuration of the single changeover output make the device adaptable to different refrigeration control strategies. Rated switching current of 16 A at 230 V AC supports direct control of common refrigeration loads without additional relays in many installations. Supplied without an integrated probe, the controller allows selection of an appropriate external sensor for the required measurement point and cable length.

Suitable for

• Commercial and light industrial refrigeration cabinets and cold rooms
• Control of compressors, evaporator fans and defrost circuits
• Retrofit or new installations where DIN-rail mounting is preferred

Key specifications

• Setpoint range: -4 to 5 °C
• Output: single changeover contact configurable as NO or NC
• Rated switching current: 16 A at 230 V AC
• Power supply: 230 V AC
• Mounting: DIN-rail
• Probe: not included — accepts external temperature sensor

How to use

Install the controller on a standard DIN-rail in a suitable enclosure with protection against moisture and physical damage. Connect the 230 V AC supply and the controlled load following the wiring diagram supplied with the unit, and mount an appropriate external temperature sensor at the required measurement point. Configure the setpoint within the -4 to 5 °C range and select the contact mode (normally open or normally closed) according to the control logic of the refrigeration equipment. Verify correct wiring and sensor response before applying normal operation.

Usage recommendations

Select a temperature probe with compatible accuracy and appropriate cable length for the installation environment. Locate the sensor where it will measure air or product temperature representative of the controlled space and avoid mounting close to heat-producing components. Ensure electrical connections comply with local regulations and, if switching inductive loads such as compressors, consider using protective measures or contactors if required by the load characteristics.