Eliwell EWPlus Refrigeration Controllers – Technical Reference (961 / 974 / 120V / 230V)

Overview

Eliwell EWPlus controllers are electronic temperature controllers used in commercial refrigeration systems such as cold rooms, freezers, display cases, and refrigerated equipment.

This document covers EWPlus 961 and EWPlus 974 models in both 120V and 230V versions. Exact features vary by model code and configuration.

EWPlus controllers belong to a modular platform where hardware and firmware variations may significantly affect I/O configuration and electrical ratings.

Controller Series

EWPlus Series

Digital refrigeration controllers for standard cooling applications.

EWPlus 961

Basic refrigeration controller typically used for single-evaporator or simple refrigeration systems.

EWPlus 974

Advanced controller with additional probe inputs and expanded defrost control functions.

General Specifications

Power Supply

120V AC or 230V AC versions (depending on model code)
50/60Hz operation

Operating Temperature

-5°C to +55°C

Storage Temperature

-30°C to +85°C

Temperature Display Range

-50°C to +110°C (probe dependent)

Resolution

0.1°C

Panel Cutout

71 × 29 mm (EWPlus family standard)

Inputs

Temperature Inputs (NTC)

EWPlus 961: 1 probe (Pb1)
EWPlus 974: 2 probes (Pb1 + Pb2)

Pb2 is typically used for evaporator or defrost control functions.

Digital Inputs

Typically 1 voltage-free configurable input
Functions may include:

• Door switch
• External alarm
• Standby / energy saving

Outputs

Relay Output (Compressor)

Electromechanical relay for compressor control
Rated for refrigeration loads (exact current rating depends on model variant and datasheet)

EWPlus 974 may also include additional outputs such as fan or auxiliary relay depending on configuration.

Control Logic

Temperature measured via NTC probe(s)
Compressor turns ON when temperature rises above setpoint + differential
Compressor turns OFF when setpoint is reached
Anti-short-cycle delay protects compressor from rapid cycling
Defrost cycles operate based on time or probe termination (model dependent)

Defrost (EWPlus 974 Enhanced)

• Electric defrost
• Off-cycle defrost
• Hot gas defrost (depending on system configuration)

Defrost termination may be based on time or evaporator probe (Pb2).

Fault Codes

E1 – Probe 1 Fault (Pb1)

Open or short circuit in temperature probe

E2 – Probe 2 Fault (Pb2)

Evaporator probe failure (EWPlus 974 models)

AH – High Temperature Alarm

Temperature above alarm threshold

AL – Low Temperature Alarm

Temperature below alarm threshold

Applications

• Commercial refrigeration units
• Walk-in cold rooms
• Freezers (system dependent)
• Display refrigeration cabinets
• Food service refrigeration equipment

Model Differences

EWPlus 961

• Single probe system
• Basic refrigeration control logic

EWPlus 974

• Dual probe system
• Enhanced defrost control
• Expanded configuration options

Technical Note

Physical & Environmental Ratings

• Front panel protection: IP65 (front-mounted protection, model dependent)
• Casing: PC+ABS UL94 V-0 resin with polycarbonate window and thermoplastic keys
• Front panel dimensions: varies by model variant (cutout typically 71 × 29 mm, bezel dimensions may differ)
• Humidity: 10–90% RH non-condensing (operating and storage)

Relay Output Ratings

Relay ratings vary between EWPlus model variants. Always verify the exact electrical rating on the label of the installed controller or in the official datasheet.

• Compressor relay: load rating varies by model variant (typically specified in amperes for inductive loads)
• Some variants may be marketed with equivalent HP/FLA/LRA values for application reference only
• Fan relay (where fitted): auxiliary output with lower current rating than compressor relay

Note: Do not exceed the rated load of the installed controller. For higher power compressors or motors, use an external contactor.

Programming Interface

EWPlus controllers support parameter configuration via keypad and external cloning tools depending on model version.

• TTL serial programming port (used with Eliwell Copy Card / UNICARD / compatible accessories)
• Accessory connection via dedicated programming interface (model dependent)
• Parameters are typically organised into installer and user levels (PA1 / PA2 structure)
• Keypad lock function available via configuration parameter (LOC)

Parameter cloning behavior may vary depending on firmware version and accessory type.

After parameter changes or cloning operations, a power cycle is recommended to ensure proper configuration loading.

All EWPlus controllers are configuration-based systems. Inputs, outputs, and functions may vary depending on model code, firmware version, and voltage variant (120V / 230V). Always verify the official Eliwell datasheet for the exact installed model.

See our full selection of digital temperature controllers and refrigeration thermostats for commercial coolers, freezers, chillers, and refrigeration systems. View All Industrial Temperature Controllers

Learn more about how digital control systems compare to older mechanical solutions in our guide: Industrial Digital Thermostat vs Mechanical Temperature Controllers