Orion System SA E-BUS Controller - Manual (Page 50)

Zone
Zone
Sequence of Operations
SA E-BUS Controller Technical Guide
50
SA E-BUS Controller Alarms
SA E-BUS Controller Alarms
Sensor Failure Alarms
Supply Air Temperature Sensor Failure Alarm
The Supply Air Temperature Sensor Failure Alarm is generated when the
controller detects an open or short circuit on the Supply Air Temperature
Sensor input. Once the alarm is generated, the unit will be completely
shut down. If a sensor is properly detected after the unit has alarmed,
the alarm will be cleared and the unit will restart operations.
Entering Air Temperature Sensor Failure Alarm
The Entering Air Temperature Sensor Failure Alarm is generated when
the controller detects an open or short circuit on the Outdoor Air Tem-
perature Sensor input.
Space Temperature Sensor Failure Alarm
If the Space Sensor is confi gured as the Controlling Sensor (Mode En-
able Sensor) or as the Reset Sensor, and if the controller detects an open
or short circuit on the Space Sensor input, then a Space Temperature
Sensor Failure Alarm is generated. If the Space Sensor is confi gured as
the Controlling Sensor and the Failure Alarm is generated, the unit will
shut down. If the Space Sensor is only confi gured as a Reset Sensor and
the Failure Alarm is generated, the Space Temperature will default to a
value half way between the Heating and Cooling Mode Enable Setpoints,
and the unit will continue to run.
Mechanical Failure Alarms
Mechanical Cooling Failure
The Mechanical Cooling Failure Alarm is generated if the Supply Air
Temperature fails to drop 5 degrees (within a user-adjustable time pe-
riod) from the temperature the supply air was at when the cooling was
activated. The alarm will be cleared when the Supply Air Temperature
drops the 5 degrees and sets the failure timer back to zero. This alarm
does not apply for Modulating Cooling.
Mechanical Heating Failure
The Mechanical Heating Failure Alarm is generated if the Supply Air
Temperature fails to rise 5 degrees (within a user-adjustable time pe-
riod) from the temperature the supply air was at when the heating was
activated. The alarm will be cleared when the Supply Air Temperature
rises the 5 degrees and sets the failure timer back to zero. This alarm
does not apply for Modulating Heating.
Proof of Air Flow Alarm
A Proof of Flow switch (by others) provides a 24 VAC wet contact
closure when the Supply Fan is operating. If this contact opens while
the fan is being called to run, all heating and cooling is disabled, and
a Fan Proving Alarm is generated. Fan Proving needs to be confi gured
for this alarm to occur.
Dirty Filter Alarm
A differential pressure switch (by others) is used to provide a 24 VAC
wet contact closure to indicate a dirty fi lter status. A Dirty Filter Alarm is
then generated. Dirty Filter needs to be confi gured for this alarm to occur.
Emergency Shutdown (Smoke) Alarm
A 24 VAC wet contact input is available to be used when a N.C. Smoke
Detector, Firestat, or other shutdown condition occurs. If this contact
opens, it will initiate shutdown of the SA and will generate an alarm con-
dition. This contact closure does not produce an instantaneous shutdown.
Emergency Shutdown needs to be confi gured for this alarm to occur.
For instantaneous shutdown, the device initiating the open condition
on this contact should also be wired to cut the 24 V common to the SA
relay outputs.
Proof of Water Flow Failure
A Proof of Water Flow Switch, that provides a wet contact closure
whenever the Condenser Water Valve is operating, can be connected
to this unit.
If the Proof of Flow Switch contact opens while the Condenser Water
Valve is operating, the unit will enter the Water Proof of Flow Failure
mode. In this mode, the mechanical cooling will be deactivated and the
Condenser Water Valve will be forced to 100%.
The unit will exit this mode when the Water Proof of Flow Switch is
closed again and water fl ow is proven.
Drain Pan Overfl ow Failure
A Drain Pan Overfl ow Switch provides a wet contact closure whenever
the Supply Fan is operating and the Drain Pan is not in an overfl ow
condition. If this contact opens while the Supply Fan is operating, the
controller will enter Drain Pan Overfl ow Failure Mode and deactivate
mechanical cooling.