Carrier PC211 Start-Up, Operation And Maintenance Instructions Manual page 75

Deadband
This is the tolerance on the chilled water/ brine temperature CONTROL POINT . If the water
temperature goes outside of the DEADBAND , the PIC opens or closes the guide vanes in
response until it is within tolerance. The PIC may be configured with a 0.5 to 2 F (0.3 to 1.1 C)
deadband. DEADBAND may be viewed or modified on the Equipment Service1 table.
For example, a 1° F (0.6° C) deadband setting controls the water temperature within ±0.5° F
(0.3° C) of the control point. This may cause frequent guide vane movement if the chilled water
load fluctuates frequently. A value of 1° F (0.6° C) is the default setting.
Proportional Bands and Gain
Proportional band is the rate at which the guide vane position is corrected in proportion to
how far the chilled water/brine temperature is from the control point. Proportional gain
determines how quickly the guide vanes react to how quickly the temperature is moving from
CONTROL POINT.
The proportional band can be viewed/modified on the LID. There are two response modes,
one for temperature response above the control point, the other for response below the control
point.
The first type is called PROPORTIONAL INC BAND , and it can slow or quicken vane
response to chilled water/brine temperature above DEADBAND . It can be adjusted from a
setting of 2 to 10; the default setting is 6.5. PROPORTIONAL DEC BAND can slow or quicken