IOM 1206-1
49
Alarms
Reset:
While still running, the event will be reset if
evaporator pressure > Low Evaporator Pressure Hold SP
+ 90 KPA(13 PSI). The event is also reset if the circuit is
no longer in the run state.
High Condenser Pressure - Unload
Trigger:
This event is triggered if all of the following are true:
·
circuit state = Run
·
more than one compressor is running on the
circuit
·
condenser pressure > High Condenser Pressure –
Unload set point
Action Taken:
Stage off one compressor on the circuit
every 10 seconds while condenser pressure is higher than
the unload set point, except the last one. Inhibit staging
more compressors on until the condition resets.
Reset:
While still running, the event will be reset if
condenser pressure <= High Condenser Pressure Unload
SP – 862 KPA(125 PSI). The event is also reset if the
circuit is no longer in the run state.
Circuit Warning Alarms
Failed Pumpdown
Trigger:
Circuit state = pumpdown for longer than 2
minutes.
Action Taken:
Rapid stop circuit.
Reset:
N/A.
Alarm Logs
NOTE
:
refer to
Figure 18
for controller components.
Press the alarm button on the controller to go to the alarm
section. Three alarm sub-sections will appear. Turn the
navigating wheel to highlight among them and press the
wheel to select.
1. Active Alarms
When an alarm or event occurs, it appears in the active
alarm list. The active alarm list holds a record of all
active alarms not yet cleared and includes the date and
time each occurred. When cleared, the alarm transfers to
the Alarm Log that contains an alarm history with time/
date stamp. A (+) before an alarm indicates that it is
active, a (-) indicates a cleared alarm. The Active Alarm
list is only limited by the number of alarms since any
given alarm cannot appear twice.
2. Alarm Log
An alarm log stores the last 50 occurrences or resets that
occur. When an alarm or event occurs, it is put into the
first slot in the alarm log and all others are moved down
one, dropping the last entry. The date and time the alarm
occurred are stored in the alarm log.
3. Event Log
An Event Log similar to the Alarm Log stores the last 50
event occurrences. Each Event Log entry includes an
event description and a time and date stamp for the event
occurrence plus the count of the event occurrences on the
current day and for each of the last seven days. Events do
not appear in the Active Alarm list.
Clearing Alarms
Active alarms can be cleared through the keypad/display
or a BAS network. Alarms are automatically cleared
when controller power is cycled. Alarms are cleared only
if the conditions required to initiate the alarm no longer
exist. All alarms and groups of alarms can be cleared via
the keypad or network via LON using nviClearAlarms
and via BACnet using the ClearAlarms object.
To use the keypad, follow the Alarm links to the Alarms
screen, which will show Active Alarms and Alarm Log.
Select Active Alarm and press the wheel to view the
Alarm List (list of current active alarms). They are in
order of occurrence with the most recent on top. The
second line on the screen shows Alm Cnt (number of
alarms currently active) and the status of the alarm clear
function. Off indicates that the Clear function is off and
the alarm is not cleared. Press the wheel to go to the edit
mode. The Alm Clr (alarm clear) parameter will be
highlighted with OFF showing. To clear all alarms, rotate
the wheel to select ON and enter it by pressing the wheel.
An active password is not necessary to clear alarms.
If the problem(s) causing the alarm have been corrected,
the alarms will be cleared, disappear from the Active
Alarm list and be posted in the Alarm Log. If not
corrected, the On will immediately change back to OFF
and the unit will remain in the alarm condition.
