Chiller Capacity Control (SYS-04 = 2)

This function requires that the input average chiller capacity “AvgCap“ is connected.

The average chiller capacity is a 0…100% signal calculated by the chiller add-on module “CAA_ChillerAddOnCmd“. It is the average chiller capacity of the operating chillers. The average chiller capacity is calculated using the chiller electric power meter or the chilled water flow and chilled water differential temperature.

The calculated number of stages increments by one when the average chiller capacity is higher than high limit defined by parameter ACP-01 for a time period defined by parameter SYS-02.

The calculated number of stages decrements by one when the average chiller capacity is lower than low limit defined by parameter ACP-02 for a time period defined by parameter SYS-03.

The first chiller is commanded when the system return temperature is higher than the chilled water return temperature setpoint defined by the datapoint “SysRetTempSp“ for a time period defined by parameter SYS-02.

Table 6.   Parameter List

Description

Value Range

Default Value

Unit

ACP-01: high limit increase chillers

0…100

80

%

ACP-02: low limit decrease chillers

0…100

30

%

SYS-02: increase delay

0…3600

1200

sec

SYS-03: decrease delay

0…3600

600

sec