42
42. Purge Pumpout Interval Setpoint
This setpoint sets the interval between absorber purge
chamber pumpout cycles.
Range 10-250 minutes. Default at 60 minutes.
43. Purge Pumpout Duration Setpoint.
This setpoint sets the length of each Absorber pumpout
cycle. (The length of time that the Absorber chambers
motorized pumpout valve is energized.) Typically set to 0
minutes when not used.
Range 0-10 minutes, Default at 10 minutes.
Optional Flow Display Settings (Option)
With this option two-design points that reflect the pressure
drop curve must be selected. One can be the job specific
design point and the other selected from an appropriate
pressure drop curve or alternate selection output. This
information is then input in the following screens.
44. Low Evaporator Water Flow Warning Setpoint
The following will be displayed only if the Differential Water
Sensing Option is installed.
Range of values is 0.0 to 4.0 gpm or ton (lpm or ton) in
increments of 0.1.
45. Variable Flow Rate Control
The following will be displayed only if the Differential Water
Press Sensor Option is installed. This screen allows the
feature to be enabled or disabled. Variations in evap water
flow will be recognized as a control input to improve
machine control. The default is disabled.
46. Evaporator Flow Rate - High
Enter the higher point flow rate.
Range of Values is 100 to 7000 in increments of 1. Module
Default is 1750.
46. Evaporator Flow Rate - Low
Enter the lower point flow rate.
Range of Values is 100 to 7000 in increments of 1. Module
Default is 700.
48. Evaporator Pressure Drop - High
Enter the pressure drop at the higher flow rate.
Range of Values is 1 to 255.
49. Evaporator Pressure Drop - High
Enter the corresponding pressure drop at the lower flow
rate. Range of Values is 1 to 255.
50. Evaporator Fluid Coefficient
This input identifies the proper fluid characteristics. Water is
100. (This number is found by multiplying the specific
gravity times the specific heat times 100.)
51. Absorber or Condenser Flow Rate - High
Enter the higher point flow rate.
Range of Values is 100 to 7000 in increments of 1. Module
Default is 1750.
52. Absorber or Condenser Flow Rate - Low
Enter the higher point flow rate.
Range of Values is 100 to 7000 in increments of 1. Module
Default is 750.
53. Absorber or Condenser Pressure Drop - High
Enter the corresponding pressure drop at the higher flow
rate.
Range of Values is 1 to 255.
54. Absorber or Condenser Pressure Drop - Low
Enter the corresponding pressure drop at the lower flow
rate.
Range of Values is 1 to 255.
Energy Input
The various energy-input devices have different energy
input levels with a constant command signal level when a
linear command signal is utilized. For example, when
commanding a butterfly type valve to open 25% with a 25%
command signal, there would be more energy input
because of the nature of butterfly valves. (for example, As
the valve is first opened through its first part of actuation, a
higher rate of energy is input to the chiller than during the
later portion of the valve travel.) For this reason the control
system can be modified using the energy input coefficient
to attain a more linear input characteristic. This is done by
altering the input command signal depending on the
energy-input device. Figures 9, 10 and 11 illustrate three
different scenarios. Figure 10 illustrates the butterfly
scenario and indicates how the command signal will be
reduced during the first part of the operation. There are four
values to be entered.