Emerson 3000/ITR Pump Down-AirCooled with Condenser Only Units, High Pressure Alarm, Operation

Operation

Pump Down—Air Cooled with Condenser Only Units

NOTE

Pump down activation is determined by the type of unit; these units do not have a pump-down function: Glycol, GLYCOOL and remote condensing units.

The Pump Down operation is performed to protect the compressor oil from being diluted with liquid refrigerant, which helps ensure that the compressor is properly lubricated for the next startup. The Pump Down operation operates in the following manner:

Pump down is always performed loaded (for digital scroll: control solenoid valve disabled).

Digital Scroll Only: When pump down has finished successfully, pump down will be continued for another half-second with the control solenoid valve energized.

High Pressure Alarm

When the compressor is initially activated, the system will be monitored for a high pressure situation. When a high pressure situation is detected during the first 10 minutes of operation, the unit will attempt to correct the problem several times without notification. This alarm will automatically reset when the pressure drops to an acceptable operating range. If the unit is unsuccessful in correcting the problem, an alarm will occur and the affected compressor will be locked Off. If high head pressure alarm trips three times in a rolling 12 hour period, the affected compressor will be locked Off.

Once the compressor is locked Off, it will not come back On until main power is reset, or until the HP Alarm Counters (Service Menu, Diagnostics) are reset to 0.

NOTE

If the unit is equipped with manual reset high head pressure switches, or if the auto reset high head pressure switches don’t reset, the compressor will not be turned back On, but there will be a 30-second delay from when the high head pressure situation occurs and when the alarm is annunciated.

Digital Scroll High Temperature

A protective maximum operating compressor temperature limit is imposed on units with digital scroll compressor(s) with thermistor. Once the digital scroll temperature reaches the maximum tempera- ture threshold, the compressor will be locked out for at least 30 minutes and an alarm will be annun- ciated. If after 30 minutes the temperature has cooled to a safe operating temperature, the compressor will resume operation.

The HT 1 Alarm Counter (Service Menu, Diagnostics) records the number of high-temperature alarms. Once these counters reach five occurrences in a rolling four-hour period, the compressor will be locked out. The alarm can be reset once the temperature returns to a safe level by:

1.Setting the counter back to 0 from the display and pressing the alarm reset button.

2.Shutting Off power to the control board by turning the cooling unit's main power disconnect switch Off and On.

5.1.3Compressor Timing

To help maximize the life of your compressor(s), there is a start-to-next start delay for each single compressor.

A Minimum On time and a Minimum Off time may be selected in the Advanced menu (minimum three minutes for single phase compressors). Consult the factory on how to modify the Minimum On and Off time settings.

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