Trane IntelliPak with Symbio 800, Инструкция по установке, эксплуатации и обслуживанию

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82 RT-SVX063G-EN
Table 33. EXV Control States (continued)
Control State Description
Running – Pre-Position Hold Time After a compressor on the circuit starts, but before automatic control begins.
Running – Suction Superheat Control Normal automatic superheat control
Running – Suction Pressure Control Controlling suction pressure instead of suction superheat, to maintain
adequate compressor pressure ratio or to limit high suction saturated
temperature.
Running – Evaporator Dryout Control Special version of suction pressure control, to dry out a flooded evaporator and
prepare to control suction superheat or suction pressure again.
Operating Modes
Calibrating_EXV
Circuit submode displayed when EXV is going through the
calibration process. Most often active when circuit top-level
mode is Stopped, Run Inhibit, or Auto.
Prepositioning_EXV
Circuit submode displayed when EXV(s) are moving
toward their commanded pre-position opening prior to
starting the first compressor on circuit startup.
Manual_Override_EvapXY
Displayed when performing manual control override on the
EXV in the EvapXY position.
Economizing
Symbio 800 supports a common minimum outdoor air and
economizer damper (i.e. no separate minimum outdoor air
damper). Economizer high-limit decision methods are
defined as follows.
Table 34. Economizer high-limit decision methods
Fixed Dry Bulb
Enable
Outdoor Air Temperature < Economizer Outdoor Air Enable Setpoint – 5°F
Disable
Outdoor Air Temperature > Economizer Outdoor Air Enable Setpoint
Reference En Fixed Dry
Bulb
Enable
Outdoor Air Enthalpy < Reference Enthalpy Setpoint – 3 BTU/lb
AND
Outdoor Air Temperaure < Economizer Outdoor Air Enable Setpoint – 5°F
Disable
Outdoor Air Enthalpy > Reference Enthalpy Setpoint
OR
Outdoor Air Temperaure > Economizer Outdoor Air Enable Setpoint
Comparative En Fixed Dry
Bulb
Enable
Outdoor Air Enthalpy < Return Air Enthalpy – 3 BTU/lb
AND
Outdoor Air Temperaure < Economizer Outdoor Air Enable Setpoint – 5°F
Disable
Outdoor Air Enthalpy > Return Air Enthalpy
OR
Outdoor Air Temperaure > Economizer Outdoor Air Enable Setpoint
When conditions are suitable for economizer operation, the
outdoor air damper modulates between Economizer
Minimum Position (or Flow) Setpoint and 100% open.
Economizing will not allow additional mechanical cooling
until the damper position is 100% and supply fan has
reached 100% capacity. If economizer cooling becomes
disabled, damper will revert to minimum position (or Flow)
control, and transition to mechanical cooling.
Given the economizer decision methods above, if
Comparative En Fixed Dry Bulb is configured and
the return air or humidity sensor goes out of range or fails,
a fallback method of Fixed Dry Bulb or Reference Enthalpy
+ Fixed Dry Bulb is selectable in the user interface Feature
Settings screen.
A building automation system can directly command
economizer operation via Economizer Airside Enable
(auto, enable, disable). If commanded Enable, the
controller will start economizer cooling, regardless of
outdoor air conditions. If commanded Disable, economizer
cooling will be disabled (except if a mode of Night Purge is
commanded to the controller). If commanded Auto, the
controller will use the configured Economizer high limit
method and input values to determine if economizer
cooling is available.
Outdoor Air Damper Fault
Detection and Diagnostics (FDD)
The outdoor air damper fault will have two fault detection
components, faults that are generated when operating in
minimum ventilation mode and another set when the
damper is being controlled by the economizer:
FDD: Excessive Outdoor Air
Sequence of Operation