Orion OE335-26B-VCBX-A, Техническое руководство

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Zone
Zone
SEQUENCE OF OPERATIONS
VCB-X Controller Field Technical Guide
74
Head Pressure Control and Alarms
Head Pressure Control
The VCB-X EM1 Expansion Module can monitor a Head Pressure
Transducer and control a Condenser Fan or a Condenser Water Valve
to maintain a Head Pressure Setpoint. The VCB-X Controller can
be con
fi gured for an Air Cooled Condenser (default) or for a Water
Cooled Condenser.
A Condenser Relay is commanded on when the fi rst compressor is
enabled (except if the unit is in Heat Pump Defrost Mode). On an
Air Cooled Unit, the Condenser Fan will be controlled with 0-10
VDC output signal or a PWM output signal. Both outputs operate
simultaneously. On a Water Cooled Unit, the Condenser Water Valve
will be controlled with a 2-10 VDC output signal.
When the Condenser Signal fi rst activates, it maintains at 50% for
30 seconds on an Air Cooled Unit and at 75% for 3 minutes on a
Water Cooled Unit.
In the Cooling Mode, the Condenser Signal will modulate to maintain
the Cooling Head Pressure Setpoint. For an Air Cooled Unit, the
signal can modulate between 15% and 100%. For a Water Cooled
Unit, the signal can modulate between 25% and 100%. If the Head
Pressure exceeds 550 PSIG, the condenser control signal will
immediately go to 100% and a High Head Pressure Alarm will be
generated. The alarm will be deactivated when the Head Pressure
drops below 540 PSIG.
In the Dehumidi fi cation Mode, the Condenser Output Signal controls
to the Reheat Head Pressure Setpoint. High Head Pressure conditions
produce the same effects as in the Cooling Mode.
In Heat Pump Heating Mode, the Condenser Output Signal will
be 100%. In the Defrost Mode the signal will be 0%. There is no
Defrost required in a Water Cooled Unit.
If no Head Pressure Sensor is detected, the Condenser the Condenser
Output Signal will be maintained at 100%.
Temperature Protection
Temperature Protection is activated when the Supply Air Temperature
(SAT) rises above the High Cutoff Temperature (immediate) or drops
below the Low Cutoff Temperature (for 10 minutes). Both cutoff
setpoints are user-adjustable. This mode shuts off the unit (with a 3
minute fan off delay) until the mode is cancelled.
This mode is cancelled when the SAT drops 5 degrees below the
High Cutoff Temperature Setpoint or rises 5 degrees above the Low
Temp Cutoff Temperature Setpoint or when the unit changes back
into Occupied Operation.
Outdoor Air Lockouts
The compressors are disabled during Cooling Mode when the
Outdoor Air Temperature is below the Compressor Cooling Lockout
Setpoint.
Mechanical heating is disabled when the Outdoor Air Temperature
is above the Heating Lockout Setpoint.
For Air to Air Heat Pumps, the compressors are disabled during
Heating Mode when the Outdoor Air Temperature is below the
Compressor Heating Lockout Setpoint.
System Broadcasts
An Outdoor Air Temperature Sensor reading is broadcast from
any one VCB-X Controller to any controller that does not have an
Outdoor Air Temperature Sensor.
Alarm Detection and Reporting
The VCB-X Controller continuously performs self diagnostics
during normal operation to determine if any operating failures have
occurred.
These failures (alarms) can be reported to a Touch Screen System
Manager, a Hand Held Modular Service Tool, or to a computer
running Prism 2 software.
Diagnostic LEDs on the VCB-X controller will generate “blink
codes” for certain alarm conditions.
The following are the available alarm designations for the VCB-X
Controller:
Bad SAT Sensor
Bad OAT Sensor
Bad Space Sensor
Missing Main Exp Board
Missing Co2 Sensor
Bad Compressor Discharge Sensor
Missing Suction Pressure Sensor
Missing Outdoor Air fl ow Sensor
Missing Exhaust Air fl ow Sensor
Missing Supply Air Air fl ow Sensor
Missing Return Air Air fl ow Sensor
Missing MHGRV-X Board
Missing MODGAS-X Board
Missing 12RLY Board
Mech Cooling Failure
Mech Heating Failure
Fan Proving Alarm
Dirty Filter Alarm
Emergency Shutdown
Revised 2/14/14