Carrier 30XW150-400 specifications

between the master and the slave remains less than the Lead/ Lag Balance Delta, the chiller designated as the lead will remain the lead chiller. The Lead/Lag changeover between the master and the slave chiller due to hour balance will occur dur- ing chiller operating odd days, such as day 1, day 3, and day 5 of the month, at 12:00 a.m. If a lead chiller is not designated, the master chiller will always be designated the lead chiller.

The dual chiller control algorithm has the ability to delay the start of the lag chiller in two ways. The Lead Pulldown Time parameter (Lead Pulldown Type, LPUL) is a one-time time delay initiated after starting the lead chiller, before checking whether to start an additional chiller. This time delay gives the lead chiller a chance to remove the heat that the chilled water loop picked up while being inactive during an un- occupied period. The second time delay, Lead/Lag Delay (Lag Start Timer, LLDY) is a time delay imposed between the last stage of the lead chiller and the start of the lag chiller. This pre- vents enabling the lag chiller until the lead/lag delay timer has expired.

A quicker start of the lag chiller can be accomplished by configuring the Start if Error Higher parameter (Start if Error Higher, LL.ER). If the difference between the common leav- ing water temperature and the set point is greater than the con- figured value, then the lag chiller will start.

A minimum on time for the lag chiller can be programmed with the Lag Minimum Running Time configuration (Lag

Minimum Running Time, LAG.M). This parameter causes the control to run the lag chiller for the programmed minimum on time. The Lag Unit Pump Select (Lag Unit Pump Control, LAGP) can be configured such that the pump can be on or off while the chiller is off. This parameter is only active in Parallel Chiller Operation.

For units with a Touch Pilot display, two additional steps must be completed to start the machine. On the master chiller, the Master Control Type must be configured for the start con- trol defined in the Machine Control configuration. To start the machines, the master chiller must be started with the Start/Stop button and Master Mode selected. The slave chiller must be started with the CCN Mode selected.

Each application, Parallel and Series, are described sepa- rately below.

DUAL CHILLER CONTROL FOR PARALLEL APPLI- CATIONS — To configure the master chiller for parallel applications using the Touch Pilot display, see Table 24. To configure the master chiller for parallel applications using the Navigator display, see Table 25. A power cycle is required for the values to take effect.

To configure the slave chiller for parallel applications using the Touch Pilot display, see Table 26. To configure the slave chiller for parallel applications using the Navigator display, see Table 27.

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