Emerson Liebert iCOM, Manual

Page: 28 / 172

Operation
Liebert
®
iCOM
®
for Liebert DSE
™
20
Each time a unit is powered on or off, an event is added to the Event Log in the User menu.
Figure 16 Start-stop priority switches
Autorestart
When input power returns after a power failure, the unit will return to its previous operating status:
On if it was On before the power failure, Off if it was Off.
When power returns, the autorestart time—time-selectable: Single Unit Auto Restart (Service Menu,
Options Setup)—will determine how quickly the unit restarts. If the units are on the same network,
the autorestart time runs in a loop, starting each unit in sequence, beginning with Unit # 1.
Loss of Power Alarm
A Loss of Power Alarm is activated when power is restored after an interruption. If acknowledged, the
alarm resets automatically after 30 minutes. This alarm can be set to different event types (Message,
Alarm or Warning) and can be disabled under menu item Loss of Power (Service Menu, Set Alarms).
Fan Alarm / Fan Protection Settings
The fan operation is protected by two digital devices: motor protection (optional) and a differential
pressure switch. The motor protection monitors for main fan overload (Main Fan Overload alarm) or
EC fan fault and the differential pressure switch detects a loss of airflow. If either protection device is
activated after an adjustable time delay, an audible alarm occurs, an alarm relay activates and an
event is recorded in the event log. (Main Fan Overload or EC Fan Fault and Loss of Airflow in Service
Menu > Set Alarms).
The fan delay at the unit start is always five seconds shorter than the control delay (to avoid
short-cycling components when the fan is not working).
When a main fan overload occurs, the main fan, cooling, heating, humidification and dehumidification
are disabled to prevent equipment damage; the unit status will show “Alarm Off.” The unit will
automatically resume operation once the overload condition has cleared.
When an EC fan fault occurs, the unit will continue to operate normally unless a loss of airflow alarm
occurs.
When a loss of airflow occurs, the fan(s) will continue to operate to keep the unit on line until the
problem is corrected. Cooling, heating, dehumidification and humidification are disabled.
NOTE
Customer switches: remote On/Off (if used) and display On/Off switches are in series. A
cooling unit will start only if both switches are On; if one of these switches is Off, the unit will
stop. Safety devices within the unit are also in series and will shut the unit down if applicable.
NOTE
If Remote On/Off is not used, a jumper is inserted to bypass the switch.
NOTE
Loss of Power alarm will be activated only on units that had the fan switched On before power
was lost.
NOTE
When the Main Fan Overload alarm is active, the Loss of Airflow alarm is masked out.
Remote On / Off Display On / Off