Alarm and Faults
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11.0 ALARM AND FAULTS
Alarms and faults are events that are triggered when the operation of the Liebert STS2 falls outside
the defined parameters. These events can also be triggered by: user actions, such as changing
configurations, clearing logs, etc.; failed components such as a fan failure, an SCR that is open or
closed, etc.; and system status, such as open circuit breakers, load on alternate source, etc. These
events can provide a warning or trigger the system to make a change, such as switch sources or the
recording of a history log.
The Liebert STS2 monitoring system detects and annunciates a comprehensive set of fault and alarm
conditions. Faults and alarm messages are can be viewed on the LCD touch screen or via the RS-232
port.
On the LCD touch screen, the events are shown in the Status Display panel in the lower left corner of
the touch screen and written to the Event log. You can touch a message to view a definition of an
event and a tip for troubleshooting. See 13.0 - Liebert STS2 Touch Screen Display for more
information on the touch screen.
If you are monitoring the system through the RS-232 port, see Table 9 - Terminal commands on
page 77 for the commands to view event logs, and alarm and fault lists.
Event actions can be triggered by the settings configured from the Event Masks. See 11.1 - Event
Mask for more information.
Faults — A fault indicates that a component of the Liebert STS2 has failed or has been damaged. In
the Event Display, faults are indicated in red.
Alarms — An alarm is an event caused by a significant abnormal system condition. In the Event
Display, alarms are indicated in yellow. The setpoints for many of the alarms are configurable
through the User Settings. Many alarms clear themselves when the condition is resolved. If an alarm
event mask is set to latch, the alarm messages remain active until the alarm condition has been
corrected and the RESET button is pushed. See 11.1 - Event Mask for more information on latching.
When the system is furnished with an external modem and a telephone line is connected to the
modem, the system can be programmed to automatically dial out upon occurrence of any of certain
designated alarms. The auto-dial feature can be configured for alarms using the Event Mask option in
the touch screen. See Configuring the Modem on page 94 for instructions on for setting up your
modem.

11.1 Event Mask

The Liebert STS2 gathers, processes and reports faults and alarms, collectively referred to below as
events. The Event Mask dialog box allows you to set the system’s response for specific alarms and
faults that are generated.
The following mask types are available for each event:
•Latch — If a latch is enabled for the selected event, that event remains active even if the
originating event condition clears. A latched event may only be cleared by pushing the RESET
button (ALRMRST on the LED units).
•Dial Out — If the selected event is triggered, the system automatically calls the specified
telephone numbers through a modem. For example, a page could be sent or an event could be sent
to a external terminal, via a modem. See Communication Interfaces on page 76 for more
information on configuring communications options.
•Event Log — The selected event is date/time stamped and recorded to the Event Log when the
event is triggered.
•Audible — If the selected event is triggered, an audible beeper or horn is sounded by the Liebert
STS2. The beeper continues while this event is active or latched, or until the SILENCE button
(NOAUD on the LED units) is pushed. This button must be pushed with the ALRMRST button on
the LED units.
See Event Masks on page 88 for instructions on setting the mask type via the touch screen display.
See the 12.1.4 - Setting Event Masks with the Terminal on page 84 for instructions on
configuration using the RS-232 port.