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Machine Protection and Adaptive Control
10 minutes of compressor run. After that, if the oil temperature falls below this cutout
temperature for more than 60 consecutive seconds this diagnostic is issued.
Low Oil Temperature Cutout
If the oil temperature is at or below the Low Oil Temperature Cutout, for more than 60
consecutive seconds this diagnostic will be issued stopping the compressor.
This diagnostic does not take affect during the first 10 minutes of compressor run.
High Oil Temperature Cutout
This is a latching diagnostic resulting in an immediate shutdown. Default Setpoint val-
ue: 165°F (73.9°C) Implemented to avoid overheating of the oil and the bearings.
If the oil temperature is at or above the High Oil Temperature Cut-out setpoint this di-
agnostic will be issued, which will stop the compressor. If Oil Temperature violates this
temperature cut-out for more than 120 seconds, this diagnostic is issued.
Manual Oil Pump Control
The oil pump control accepts commands to turn on the oil pump. The manual oil
pump choices will be "Auto" or "On. " When the oil pump is commanded "On, " it will
revert to "Auto" in 10 minutes, and is adjustable at Large display™ or UT ™.
Controls Chilled Water Reset (CWR)
Chilled water reset is designed for those applications where the design chilled water
temperature is not required at partial load. In these cases, the leaving chilled water
temperature setpoint can be reset upward using the CWR features.
When the CWR function is based on return water temperature, the CWR feature is
standard. When the CWR function is based on outdoor air temperature, the CWR fea-
ture is an option requiring an outdoor temperature sensor.
The type of CWR is selected in the Operator Interface settings Menu along with the Re-
set Ratio, Start Reset Setpoint, and the Maximum Reset Setpoint.
High Lift Unloading (500 Ton Family Only)
High Lift Unloading Valve directs discharge gases from the condenser through a sole-
noid valve directly into the economizer. From the economizer, this gas then flows to
the second stage compressor where the economizer normally is connected. The pur-
pose of HLUV is to increase the gas flow rate through the second stage compressor.
Bypass gas is allowed to occur using an inline normally closed solenoid valve. The
high lift unloading function is dependent on the lift (where lift is defined as the differ-
ence between Condenser Saturated Refrigerant Temperature and the Evaporator Satu-
rated Refrigerant Temperature) and on chiller load. When the high lift unloading mode
is entered, the High Lift Unloading valve is opened and the inlet guide vane close trav-
el is limited.
The HLUV valve does not modulate the flow rate, but rather is either open or closed.
Further, the valve was sized to handle a mass flow sufficient to permit operation below
35% IGV position but not necessarily to 0%. The valve was sized to permit substantial
but incomplete unloading and yet was kept as small as practicable to minimize power
requirements with HLUV operation.
Not all CVGF chillers require the bypassing of condenser gas. In some tonnages, the
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CVGF-SVX03B-EN
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