Section 4: Glossary of Control Functions

Delay

Refer to Alarm Delay, Hold Delay, and Restart Delay.

E key

The Enter key <E> at the local control panel serves two functions:

Causes data entered in setup display pages to be stored in the RAC2-8 permanent memory.

Causes selection of next unit on multi-unit displays.

Emergency Power OFF (EPO)

EPO can be initiated from a remote switch wired to the RAC2-8. This user input causes all units to be turned OFF immediately. RAC2-8 control power is maintained. This Normally Closed contact must be Open for 0.5 seconds for the input signal to be detected.

After the input signal is removed (closed), the alarm must be manually cleared. Then all units programmed to be Running are started sequentially, separated by the Restart Delay.

Emergency Power Operation

This user input activates a separate mode for operating on an emergency power source (a UPS system or standby generator) which may have limited capacity. Only units selected to be ON during this mode are running. Select ON units for this mode from the display. Autochangeover, Autosequencing, and Standby Testing are inactive during this mode to reduce power load. Units that are OFF during this mode will remain OFF until normal mode is resumed. This mode also energizes both lockout relays, Humidity and (Optional) Control.

Force ON

To manually turn a unit ON from the display. Refer to Override.

Force OFF

To manually turn a unit OFF from the display. Refer to Override.

Hold Delay

Delay after turn ON of a Standby unit to allow the newly started unit to gain control. During the Hold Delay alarms from this unit and all other units are ignored. This delay begins when any changeover Occurs, either in Autosequence or Standby Test mode. An active Hold Delay can be monitored at the display. At the end of the Hold Delay, the Alarm Delay time begins. The Hold Delay is user selectable from the display.

Range—0.1 to 60 minutes, selectable in increments of 0.1 minute (6 seconds).

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Liebert RAC2-8 manual Emergency Power OFF EPO, Emergency Power Operation, Force on, Force OFF, Hold Delay