Carrier 30XW150-400 specifications Circuit/Compressor Staging and Loading

Machine Start Delay — An option to delay the start of the machine is also available. This parameter is useful in keep- ing multiple machines from starting at the same time in case of a power failure. The parameter has a factory default of 1 minute. This parameter also has a role in the timing for a chilled water flow switch alarm. The flow switch status is not checked until the delay time has elapsed.

To configure this option with the Touch Pilot display:

DISPLAY NAME		PATH		LINE		VALUE
				NO.
Unit Off to		Main Menu		6	Default = 1 Minute
On Delay		→ Config→ USER
To configure this option with the Navigator display:
ITEM	ITEM EXPANSION			PATH			VALUE
DELY	Minutes Off Time		Configuration→ OPTN				Default =
							1 Minute

Circuit/Compressor Staging and Loading —

The AquaForce® 30XW chillers employ one compressor per circuit. As a result, circuit and compressor staging are the same. The control has several control option parameters to load the compressors. The circuit/compressor start can be config- ured as well as the loading of each circuit/compressor.

CIRCUIT/COMPRESSOR STAGING — The control can be configured to decide which circuit/compressor starts first, by configuring Lead/Lag Circuit Select (Staged Loading Sequence, LLCS). Three options for this variable are allowed: Automatic Lead-Lag, Circuit A Leads or Circuit B Leads. The factory default is Automatic Lead-Lag.

The automatic lead-lag function determines which circuit/ compressor starts. When enabled, the control will determine which circuit/compressor starts to even the wear of the com- pressor. The compressor wear factor (combination of starts and run hours) is used to determine which compressor starts.

Compressor Wear Factor = (Compressor Starts) + 0.1 (Com- pressor Run Hours)

The circuit/compressor with the lowest compressor wear factor is the circuit that starts first.

If starting a particular circuit/compressor first is desired, that can also be configured with the same variable.

To configure this option with the Touch Pilot display:

DISPLAY NAME	PATH	LINE		VALUE
		NO.
			0	(Automatic Lead-lag)
Circuit Loading	Main Menu		1	(Circuit A Leads)
		1	2	(Circuit B Leads)
Sequence	→ Config→ USER
			Default = 0
			(Automatic Lead-lag)

To configure this option with the Navigator display:

ITEM	ITEM EXPANSION	PATH	VALUE
			Range: Automatic,
LLCS	Lead/Lag	Configuration	Cir A Leads,
			Cir B Leads,
	Circuit Select	→ OPTN
			Cir C Leads
			Default – Automatic

CIRCUIT/COMPRESSOR LOADING — The control can be configured to stage the circuit/compressors. The Loading Sequence Select (Circuit Loading Sequence, LOAD) setting determines how the control will perform loading. The configu- ration can be set to Equal or Staged.

Equal Loading — With Equal loading, the circuit which starts first will maintain the minimum stage of capacity with the slide valve fully unloaded. When additional capacity is required, the next circuit with the lowest compressor wear factor is started with its slide valve at minimum position. As additional capaci- ty is required, the slide valve for a circuit will be adjusted in approximately 5% increments to match capacity requirements.

The control will alternate between circuits to maintain the same percentage of capacity on each circuit.

Staged Loading — If staged loading is selected, the circuit which starts first will gradually load its slide valve to match capacity requirements until the circuit is fully loaded. Once the circuit is fully loaded and additional capacity is required, the control will start an additional circuit fully unloaded. The con- trol will gradually unload the circuit which was fully loaded to match capacity requirements.

To configure this option with the Touch Pilot™ display:

DISPLAY NAME			PATH	LINE		VALUE
				NO.
Staged Loading		Main				Default = No
				4		No (Equal)
Sequence		Menu→ Config→ USER
						Yes (Staged)
To configure this option with the Navigator™ display:
ITEM	ITEM EXPANSION		PATH			VALUE
LOAD	Loading Sequence		Configuration→ OPTN		Default = Equal
					Equal
	Select				Staged

Minimum Load Control — Minimum Load Control can be a factory-installed option or a field-installed accessory. If installed, and its operation is desired, the Minimum Load Control must be enabled. Once enabled, the valve will be oper- ational only during the first stage of cooling.

To configure this option with the Touch Pilot display:

DISPLAY NAME	PATH	LINE	VALUE
		NO.
			Default = No
Hot Gas	Main		No (No Minimum
	Menu→ Service	14	Load Control)
Bypass Select
	→ FACTORY		Yes (Minimum Load
			Control Installed)

A power cycle is required for the values to take effect. To configure this option with the Navigator display:

ITEM	ITEM	PATH	VALUE
	EXPANSION
			No = No Minimum
HGBP	Hot Gas	Configuration→ UNIT	Load Control
	Bypass Select		Yes = Minimum Load
			Control Installed

A power cycle is required for the values to take effect.

Dual Chiller Control — The dual chiller routine is available for the control of two units installed in series or paral- lel supplying chilled fluid on a common loop. One chiller must be configured as the master chiller, the other as the slave chill- er. An additional leaving fluid temperature thermistor (dual chiller LWT) must be installed in the common chilled water piping as described in the Installation Instructions for both the master and slave chillers. See the Field Wiring section in the 30XW Installation Instructions for dual chiller LWT sensor control wiring.

The control algorithm relies on several parameters that must be field configured for operation. Both chillers must be on the same Carrier Comfort Network® bus with different addresses. On both chillers, Master/Slave Select (Master/Slave Select, MSSL) must be enabled. The water piping arrangement, Chill- ers in Series (Chiller in Series, SERI), must be configured. The master chiller must be programmed with the Slave Chiller Address (Slave Address, SLVA). Additional optional pro- gramming parameters may be configured to meet application requirements.

Lead/Lag Balance Select (Lead Lag Select, LLBL) deter- mines which chiller is the lead machine. The options are Al- ways Lead, Lag if Fail, and Runtime Select. Under Runtime Select control, the lead chiller will change based on the time in- crement selected in the Lead/Lag Balance Delta configuration (Lead/Lag Balance Data, LLBD). If the run hour difference

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