Carrier 30XW150-400 Dual Chiller Sequence of Operation With a, 30XW Operating Modes

OPERATION

Sequence of Operation — With a command to start the chiller, the cooler and condenser pumps will start. After verifying water flow, the control will monitor the entering and leaving water temperatures. If the need for mechanical cooling is determined, the control decides which circuit and compres- sor to start. The control will start the required compressor com- pletely unloaded. The control will continue to load this circuit by moving the slide valve to satisfy cooling requirements. Once fully loaded, the control will start an additional circuit to satisfy the load as required. Shutdown of each circuit under normal conditions occurs in the opposite sequence to loading. Once the circuit is fully unloaded the compressor is shut off and the EXV will close completely.

Dual Chiller Sequence of Operation — With a

command to start the chiller, the master chiller determines which chiller will become the lead chiller based on the configu- ration of Lead Lag Select, LLBL and Lead/Lag Balance Da- ta, LLBD. The lead chiller is always started first and the lag chiller is held at zero percent capacity by the master chiller forcing the lag demand limit value to 0%. If Lead Pulldown Time (Lead Pulldown Time, LPUL) has been configured, the lead chiller will continue to operate alone for that specified time. After the Lead Pulldown Time timer has elapsed and when the lead chiller is fully loaded, either all available com- pression is on or at the master demand limit value, then the lag start timer (Lag Start Timer, LLDY) is initiated. When the pulldown timer and lag start timer has elapsed and the Com- bined Leaving Chilled Water Temperature is more than 3° F (1.7° C) above the set point, then the lag chiller is started. If the lag chiller’s water pump was not started when the machines went into occupied mode, the lag chiller water pump will be started. The lag chiller will start with the master chiller forcing the lag chiller demand limit value (LAG_LIM) to the master’s demand limit value. If lead/lag capacity balance is selected, once the lag chiller has started, the master shall try to keep the difference in capacity between lead and lag less than 20%. The master shall then be responsible for water loop capacity

calculation, and will determine which chiller, the lead or lag, will increase or decrease capacity. When the load reduces, the lag chiller will be the first chiller to unload. To accomplish this, the lead chiller set point is decreased by 4° F (2.2° C) until the lag chiller unloads.

PUMP OPERATION — For parallel chiller pump operation, the lead chiller’s water pump will be started. The lag chiller’s water pump will be maintained off if Lag Unit Pump Control, LAGP=0. The internal algorithm of lead chiller will control ca- pacity of the lead chiller.

For series chiller operation, the pump is always controlled by the master chiller.

Operating Modes — Operating modes are override modes that affect normal operation of the equipment. More than one operating mode can be in effect at the same time. Some operating modes have corresponding capacity control overrides in the Capacity Control Overrides section on page 43.

For the Touch Pilot display, the status of the operating modes can be found in the MODES submenu, which is under the STATUS menu. Each operating mode and its status (Yes = active, No = inactive) is listed.

For the Navigator display, the status of the operating modes can be found in the MODE submenu under the OPERATING MODES menu. The 6 top priority operating modes are dis- played in MD01 through MD06. To view the modes with the Navigator display:

ITEM	ITEM EXPANSION	PATH	VALUE
MD01	First Active Mode	Operating modes→ MODE	0-32
MD02	Second Active Mode	Operating modes→ MODE	0-32
MD03	Third Active Mode	Operating modes→ MODE	0-32
MD04	Fourth Active Mode	Operating modes→ MODE	0-32
MD05	Fifth Active Mode	Operating modes→ MODE	0-32
MD06	Sixth Active Mode	Operating modes→ MODE	0-32

See Table 37 for a list of operating modes.

Table 37 — 30XW Operating Modes

NAVIGATOR OPERATING	NAVIGATOR EXPANSION	TOUCH PILOT DISCRIPTION	TOUCH PILOT	TOUCH PILOT
MODE NUMBER			LINE NUMBER	VALUE
01	Startup Delay in Effect	Startup Delay in Effect	2	Yes/No
02	Second Setpoint in Use	Second Setpoint in Use	3	Yes/No
03	Reset in Effect	Reset in Effect	4	Yes/No
04	Demand Limit Active	Demand Limit Active	5	Yes/No
05	Ramp Loading Active	Ramp Loading Active	6	Yes/No
06	Cooler Heater Active	Cooler Heater Active	7	Yes/No
07	Cooler Pumps Rotation	Cooler Pumps Rotation	8	Yes/No
08	Pump Periodic Start	Pump Periodic Start	9	Yes/No
09	Night Low Noise Active	Night Low Noise Active	10	Yes/No
10	System Manager Active	System Manager Active	11	Yes/No
11	Mast Slave Ctrl Active	Mast Slave Active	12	Yes/No
12	Auto Changeover Active	Auto Changeover Active	13	Yes/No
13	Free Cooling Active	Free Cooling Active	14	Yes/No
14	Reclaim Active	Reclaim Active	15	Yes/No
15	Electric Heat Active	Electric Heat Active	16	Yes/No
16	Heating Low EWT Lockout	Heating Low EWT Lockout	17	Yes/No
17	Condenser Pumps Rotation	Condenser Pumps Rotation	18	Yes/No
18	Ice Mode in Effect	Ice Mode in Effect	19	Yes/No
19	Defrost Active on Cir A	Defrost Active on Cir A	20	Yes/No
20	Defrost Active on Cir B	Defrost Active on Cir B	21	Yes/No
21	Low Suction Circuit A	Low Suction Circuit A	22	Yes/No
22	Low Suction Circuit B	Low Suction Circuit B	23	Yes/No
24	High DGT Circuit A	High DGT Circuit A	25	Yes/No
25	High DGT Circuit B	High DGT Circuit B	26	Yes/No
27	High Pres Override Cir A	High Pres Override Cir A	28	Yes/No
28	High Pres Override Cir B	High Pres Override Cir B	29	Yes/No
30	Low Superheat Circuit A	Low Superheat Circuit A	31	Yes/No
31	Low Superheat Circuit B	Low Superheat Circuit B	32	Yes/No

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