OM WGS-5
WGS 130A to 190A
51
(PD) algorithm (with deadband) in order to maintain the controlled parameter (CP) at the
desired value. The output is always limited between the Valve Control Range (Min)
setpoint and the Valve Control Range (Max) setpoint. A valve increment shall be computed
once every 5 seconds according to the following equation.
Increment = [(Error) * (Error Gain setpoint)] + [(Slope) * (Slope Gain setpoint)] Where:
Error = ECWT – Valve Setpoint Slope = (Present CP) – (Previous CP)
When the Error is > the Valve Deadband setpoint, the valve position analog output (% of
full scale) is updated according to the following equation.
New %Position = Old %Po Increment/10.
Valve Stage Mode
This mode is only operational when the Valve/VFD Control setpoint is set to Valve Stage.
In this mode the valve output is controlled as for Valve setpoint mode (above) except that
the active setpoint for the controlled parameter is selected according to the following table.
# of Fans ON
Active Setpoint
0
Valve Setpoint
1
Stage #1 ON
2
Stage #2 ON
Cooling Tower Fan VFD
When the Valve/VFD Control setpoint is set to None, Valve Setpoint, OR Valve Stage, this
output shall be set to 0. Otherwise, it shall be controlled in a manner identical to Valve
Stage Mode (above) except that (1) it shall be kept at zero until the first fan stage is ON and
(2) the following setpoints do not apply.
Valve Control Range (Min)
Valve Control Range (Max)
Valve Type
Evaporative Condenser Control
It is acceptable to use WGS-A chillers (less condenser) with evaporative condensers. It is
the installer's responsibility to provide the evaporative condenser control because this
condenser type is not available from McQuay. The WGS-A software does not directly
support evaporative-cooled applications since there is a variety of fan configurations and
pumps available from the manufacturers of evaporative condensers. In addition, the WGS
software does not support the auxiliary functions of the evaporative condenser such as make
up water valves, sump drain valves, electronic make up water valves, water freeze
protection, variable frequency drives, damper controls or water treatment options. The
WGS software will provide equipment protection and operational limits as if it were a
remote air-cooled condenser application. See other sections of this manual for complete
descriptions.
The system must be comprised of two controls systems that operate together to make a
complete system. First, the WGS-A software provided with the unit will control the indoor
chiller section of the unit including compressor loading/unloading, equipment protection,
BAS interface (when applicable), and other functions as described in this manual without
the condenser control. The WGS software setup shall be treated as a remote air-cooled
application. The second control system is required to control the condenser and auxiliary
functions. The best method for interfacing the two systems is through the "first on, last off"
fan contacts as if the application was a remote air-cooled condenser. At start up of the
compressors, the Fan 1 Contactor fan contacts will close and activate the condenser control
Содержание WGS130AA: WGS140AW
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