Liebert RAC2-8 manual Alarm Annunciation, Alarm Communications, Alarm Delay, Autochangeover

Section 4: Glossary of Control Functions

Alarm Annunciation

The RAC2-8 provides the following alarm annunciation mechanisms:

•Audible indication (horn).

•A lighted ‘Alarms Present’ front panel indicator.

•Activation of the Common Alarm relay output.

•Display of alarm messages on the front panel LCD.

Warnings activate the ‘Alarms Present’ indicator and a message on the

LCD, but no audible alarm or Common Alarm.

When an alarm occurs the LCD immediately displays a message (unless an Override screen is being displayed). Pushing the Alarms Present/Silence pushbutton acknowledges the alarm and silences the alarm horn. The alarm message is displayed until the alarm is acknowledged (silenced). After the alarm is silenced, normal status display scanning resumes.

Any alarms present are displayed during scanning of normal display pages. If more than 4 alarms are present additional pages of alarms are created as necessary. Up to 20 alarms are stored in a First-In-First-Out sequence.

Alarm Communications

EIA-232 Terminal Port—Transmits Alarm with time stamp.

EIA-232 Modem Port—Dials out alarm.

Both EIA-232 ports are compatible with SS-AMS (SiteScan Alarm

Management System).

EIA-422 (proprietary) to SiteScan monitoring system.

Alarm Delay

Delay before an alarm is annunciated (false alarm delay). This delay begins on the occurrence of an alarm condition in a unit. If the alarm condition has not corrected itself by the end of the delay period, the alarm is annunciated and an autochangeover to the standby unit Occurs. If a unit is programmed to shutdown on an alarm, the unit shuts down when the alarm is annunciated. The Alarm Delay timer counts both up and down and an active Alarm Delay timer can be monitored at the display. The Alarm Delay is user selectable from the display. Range - 0.1 to 60 minutes, in increments of 0.1 minute (6 sec).

Autochangeover

If an alarm occurs in a Running unit, a Standby unit in the same zone is started. The Running unit in alarm is stopped if it is programmed to shut down, and the Standby unit is started. The Standby unit changes status to become the Running unit and remains running until the Alarm is manually cleared. Messages are written to the terminal to record the status changes. Status screens show new unit status at the local display. After a changeover, the newly started unit may briefly have a High Temp or other alarm. A user selectable Hold Delay begins when any

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