DynaView Interface
17RLC-SVU05A-E4
Circuit Level Mode
Top Level Mode Description
Running
The compressor on the given circuit is currently running.
Running
Sub Modes
Description
Establishing Min(imum)* Cap(acity)* - Low
Diff(errential)* Pressure
The circuit is experiencing low system differential pressure and its compressor is being force loaded,
irregardless Chilled Water Temperature Control, to develop pressure sooner.
Establishing Min Cap - High Disch Temp
The circuit is running with high discharge temperatures and its compressor is being forced loaded to
its step load point, without regard to the leaving water temperature control, to prevent tripping on high
compressor discharge temperature.
The following modes annunciations have not been implemented as a display but are actually operational in the EXV liquid level control algorithm. The
modes included here as possible future annunciated modes
EXV Controlling Differential Pressure
Liquid level control of the Electronic Expansion Valve has temporarily been suspended. The EXV is
being modulated to control for a minimum differential pressure. This control implies low liquid levels
and higher approach temperatures, but only as is necessary to provide minimum oil flow for the
compressor until the condenser water loop can warm up to approx 50F. (Future mode display - display
of mode not implemented in Phase 1 or 2 although present in algorithms.)
EXV Controlling for Low Evaporator Pressure
Liquid level control of the Electronic Expansion Valve has temporarily been suspended. The EXV is
being modulated to control for a minimum evaporator pressure that is based of the pressure of the
Low Refrigerant Temperature Cutout. This control will tend to increase the liquid level above the
setpoint or to open the valve more quickly than liquid level control can, in order to avoid an LRTC trip.
It is most often invoked transiently to help open the EXV in the event of rapidly falling liquid level and
rapidly declining evaporator pressures. (Future Mode display, - display of mode not implemented in
Phase 1 or 2 although present in algorithms.)
Circuit Level Mode
Top Level Mode Description
Running - Limit
The circuit, and compressor are currently running, but the operation of the chiller/compressor is being
actively limited by the controls. Further information is provided by the sub-mode.* See the section
below regarding criteria for annunciation of limit modes
Running - Limit
Sub Modes
Description
Current Limit
The compressor is running and its capacity is being limited by high currents. The current limit setting
is 120% RLA (to avoid overcurrent trips) or lower as set by the compressor's "share" of the active
current limit (demand limit) setting for the entire chiller.*
High Condenser Pressure Limit
The circuit is experiencing condenser pressures at or near the condenser limit setting. Compressors
on the circuit will be unloaded to prevent exceeding the limits.*
Low Evaporator Rfgt Temperature Limit
The circuit is experiencing saturated evaporator temperatures at or near the Low Refrigerant
Temperature Cutout setting. Compressors on the circuit will be unloaded to prevent tripping. *
Hot Start Limit
This mode will occur if the leaving evaporator water temperature exceeds 75F (for SW version 6.30
and earlier) or 90 F (for software 7.01 and later) at the point at which the step load for the respective
circuit would be desired. This is often the case in a high water temperature pulldown. While in this
mode, no compressor on the circuit will be allowed to load past its minimum load capacity step, but it
will not inhibit other compressors from staging on. This mode is necessary to prevent nuisance trips
due to Compressor Overcurrent or High Pressure Cutout. Reasonable pulldown rates can still be
expected despite this limit, since the compressor's capacity even at partial load is much greater at
high suction temperatures.
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