Orion System VCC-X Controller - Manual (Page 67)

VCC-X Controller Technical Guide
SEQUENCE OF OPERATIONS
67
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.
Space Temperature Sensor Failure Alarm
If the Space Sensor is confi gured as the Controlling Sensor (Mode
Enable 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.
Outdoor Air Temperature Sensor Failure Alarm
The Outdoor Air Temperature Sensor Failure Alarm is generated
when the controller detects an open or short circuit on the Outdoor
Air Temperature Sensor input. When this occurs, the Outdoor Air
reading will be artifi cially set to the half point between the Cooling
and Heating Lockout Setpoints. This will allow the cooling and the
heating to continue operating.
CO
2
Sensor Failure Alarm
This alarm is generated if the controller is confi gured to have a
CO
2
sensor, but does not detect it. IAQ Mode is disabled when this
occurs. If a sensor is properly detected after the unit has alarmed,
the alarm will be cleared and the unit will be return to CO
2
control
Suction Pressure Sensor Failure Alarm
If the controller detects the Suction Pressure Sensor is missing,
this alarm is generated and the unit will shut down. If the sensor is
properly detected after the unit has alarmed, the alarm will be cleared
and the unit will restart.
Airfl ow Alarms
Outdoor Airfl ow Sensor Alarm
Supply Airfl ow Sensor Alarm
Return Airfl ow Sensor Alarm
Exhaust Airfl ow Sensor Alarm
If the controller is confi gured to have any of the above air fl ow
sensors, but the controller does not detect that the sensor is connected,
then the applicable alarm will occur. If the sensor is properly detected
after the unit has alarmed, the alarm will be cleared.
Missing Expansion Module Alarm
Preheat-X Board Missing
EM1 Expansion Missing
RSMV Modules #1 - #4 Missing
Reheat Board Missing
ModGas Board Missing
12 Relay Board Missing
If the controller is confi gured to have any of the above Expansion
Boards (Modules), but the controller does not detect that board, then
the applicable alarm will occur. If the board is properly detected
after the unit has alarmed, the alarm will be cleared.
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 period) from the temperature the supply air was at when the
cooling was activated and the Supply Air Temperature is not within
5 degrees of Setpoint. The alarm will be cleared when the Supply
Air Temperature drops the 5 degrees and sets the failure timer back
to zero.
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 period) from the temperature the supply air was at when the
heating was activated and the Supply Air Temperature is not within
5 degrees of Setpoint. The alarm will be cleared when the Supply Air
Temperature rises the 5 degrees and sets the failure timer back to zero.
Proof of Flow Interlock 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 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 VCC-X and will
generate an alarm condition. 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
VCC-X relay outputs.