The N321R is a temperature controller dedicated to refrigeration applications, complete with a 3M NTC temperature sensor. The defrost cycle is accomplished by turning off the compressor at time intervals chosen by the user, with automatic defrost at programmable intervals and a manual defrost key on the front panel. Display indication does not change during defrost cycles, so the shown temperature stays representative of normal operating conditions.
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Novus N321R Datasheet Download
Technical Details
Sensor input: Pt100 (-50 to 300°C) or thermistor/NTC (-30 to +105°C)
Enclosure: IP65 front panel protection
Relay: SPDT, 1 HP 250 Vac / 1/3 HP 125 Vac (16 A Resistive), suitable for compressors up to 1HP
Resolution: 0.1°C from -19.9 to 199.9°C. Accuracy: ±0.5°C/°F ±1 digit
Adjustable hysteresis. Sampling: 1.5 per second
Working temperature: 0 to 50°C
Power supply: 85-250 Vac (internal) or 12-24 Vac/dc
Communication: RS485 Modbus RTU (optional)
Dimensions: 75 x 33 x 75mm
Frequently Asked Questions
Does the temperature display freeze or jump during defrost?
No — display indication does not change during defrost cycles, so you always see a representative temperature reading.
Can I trigger a defrost cycle manually?
Yes — a manual defrost key on the front panel lets you start a cycle on demand, in addition to the programmable automatic intervals.
What compressor sizes can this switch directly?
Up to 1HP compressors via the 16A SPDT relay — for larger compressors, an external contactor is required.
Industry Applications
- Commercial Refrigeration — automated defrost cycling for cold rooms and display cabinets.
- Cold Storage — consistent temperature display through defrost without misleading readings.
- Compressor Control — direct switching for compressors up to 1HP.