4 WGS 130A to 190A OM WGS-5
Definitions
Active Setpoint
The active setpoint is the setting in effect at any given moment. This variation occurs on
setpoints that can be altered during normal operation. Resetting the chilled water leaving
temperature setpoint by one of several methods, such as return water temperature, is an
example.
Active Capacity Limit
The active setpoint is the setting in effect at any given moment. Any one of several external
inputs can limit a compressor’s capacity below its maximum value.
Condenser Recirc Timer
A timing function, with a 30-second default, that holds off any reading of condenser water
for the duration of the timing setting. This delay allows the water sensors (especially water
temperatures) to take a more accurate reading of the condenser water system conditions.
Condenser Saturated Temperature Target
The saturated condenser temperature target is calculated by first using the following
equation:
Sat condenser temp target raw = 0.833(evaporator sat temp) + 68.34
The “raw” value is the initial calculated value. This value is then limited to a range defined
by the Condenser Saturated Temperature Target minimum and maximum setpoints. These
setpoints simply cut off the value to a working range, and this range can be limited to a
single value if the two setpoints are set to the same value.
CPU Error
These are problems caused by a malfunction of the central processing unit.
Dead Band
The dead band is a set of values associated with a setpoint such that a change in the variable
occurring within the dead band causes no action from the controller. For example, if a
temperature setpoint is 44F and it has a dead band of 2 degrees, nothing will happen until
the measured temperature is less than 42F or more than 46F.
DIN
Digital input, usually followed by a number designating the number of the input.
Discharge Superheat
Discharge superheat shall be calculated for each circuit using the following equation:
Discharge Superheat = Discharge Temperature – Condenser Saturated Temperature
Error
In the context of this manual, “Error” is the difference between the actual value of a variable
and the target setting or setpoint.
Evaporator Approach
The evaporator approach is calculated for each circuit. The equation is as follows:
Evaporator Approach = LWT – Evaporator Saturated Temperature
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