Dedicated high/low pressure switch inputs, compressor safety trips, and external alarm triggers.
Defines high and low pressure thresholds, delay times, and manual reset limits. 5. Maintenance and Troubleshooting Common Alarms
| Common Issue | Possible Cause | Likely Solution | | :--- | :--- | :--- | | | No power, faulty supply, or internal fuse blown. | Check the power supply circuit and fuses. Ensure a correct 230V or 24V supply is present. | | System runs constantly | Faulty probe, incorrect SET / SET-E values, or wrong Δt (differential) settings. | Check the sensor readings for reasonableness. Verify the setpoint values and try adjusting the differential. | | Compressor does not start | Blown fuse, faulty relay, open safety circuit (pressurestat, thermal overload), or programmed delays (e.g., anti-short cycle). | Check power to the compressor. Examine the input status of the safety devices. The display may show a "wait" symbol due to a programmed on or oF delay. | | Alarm LED is lit / beeping | Many potential causes: HA (High Pressure Alarm), LA (Low Pressure Alarm), EA (External Alarm), PAL (Pressurestat Alarm). | Use the display to read the specific alarm code (e.g., A1 , A2 ). Consult the parameters A1 through A11 to see what each alarm input is configured for. | | Erratic temperature reading | Loose or corroded NTC probe connection, or incorrect scaling of a 4-20 mA pressure transducer. | Check the tightness of connections at the probe and controller terminals. Verify the scaling parameters ( SP1 , SP2 ) for the input. | | RS-485 communication fails | Incorrect protocol settings, wiring fault, or termination issues. | Check SERIAL parameters ( Addr , bAUd ). Verify the twisted pair wiring is correct and no shields are shorting. | eliwell ewcm 900 s
Equipped with 11 relay outputs rated at 6(3)A at 250V AC. These relays are dynamically assigned via configuration to manage compressors, capacity steps, or condenser fans.
Unlike basic thermostats, the logic embedded within the Eliwell EWCM 900/S Manual enables complex handling of different compressor arrangements: EWCM 900/S rel. 5/2000 ing compressors and fans manager Maintenance and Troubleshooting Common Alarms | Common Issue
The Eliwell EWCM 900 S has the following technical specifications:
Use shielded twisted-pair cabling for pressure transducers and ground the shield at the electrical panel side only. | | System runs constantly | Faulty probe,
If you are looking for parts, retailers like Classic Automation or HOS BV often stock refurbished or new-old-stock units.