Sterling 30RA010-055 manual Cooling Set Point Select

DETAIL A

PRESSURE TRANSDUCER

INSTALLED HERE

SEE DETAIL A

Fig. 15 — Typical Motormaster® V Controller and Pressure Transducer Location (Sizes 022-030 Shown)

Operation of Machine Based on Control Method and Cooling Set Point Selection Set- tings — Machine On/Off control is determined by the configuration of the control method (CTRL) [Configuration, OPT2] and cooling set point select (CLSP) [Configuration, SLCT] variables. All models are factory configured with cool- ing set point select set to 1 (single set point, CSP1). With the control method set to 0, simply switching the Enable/Off/Re- mote Contact switch to the Enable or Remote Contact position (external contacts closed) will put the chiller in an occupied state. The control mode [Operating Modes, MODE] will be 1 (OFF LOCAL) when the switch is Off and will be 5 (ON LO- CAL) when in the Enable position or Remote Contact position with external contacts closed.

Two other control methods are available for Machine On/ Off control:

OCCUPANCY SCHEDULE (CTRL=2) — The Main Base Board will use the operating schedules as defined under the Time Clock mode in the Marquee display. These schedules are identical. The schedule number must be set to 1 for local schedule.

The schedule number can be set anywhere from 65 to 99 for operation under a SCN global schedule. The Enable/Off/ Remote Contact must be in the Enable or Remote Contact posi- tion. The control mode [Operating Modes, MODE] will be 1 when the switch is Off. The control mode will be 3 when the Enable/Off/Remote Contact switch input is On and the time of day is during an unoccupied period. Similarly, the control mode will be 7 when the time of day is during an occupied period.

SCN SCHEDULE (CTRL=3) — An external SCN device such as Flotronic™ System Manager controls the On/Off state of the machine. This SCN device forces the variable ‘CHIL_S_S’ between Start/Stop to control the chiller. The control mode [Operating Modes, MODE] will be 1 when the switch is Off. The control mode will be 2 when the Enable/Off/ Remote Contact switch input is On and the CHIL_S_S variable is ‘Stop.’ Similarly, the control mode will be 6 when the CHIL_S_S variable is ‘Start.’

Table 8 illustrates how the control method and cooling set point select variables direct the operation of the chiller and the set point to which it controls. The illustration also shows the ON/OFF state of the machine for the given combinations.

Cooling Set Point Select

SINGLE — Unit operation is based on Cooling Set Point 1 (CSP1) [Set Point, COOL].

DUAL SWITCH — Unit operation is based on Cooling Set Point 1 (CSP1) [Set Point, COOL] when the Dual Set Point switch contacts are open and Cooling Set Point 2 (CSP2) [Set Point, COOL] when they are closed.

DUAL SCN OCCUPIED — Unit operation is based on Cooling Set Point 1 (CSP1) [Set Point, COOL] during the Occupied mode and Cooling Set Point 2 (CSP2) [Set Point, COOL] during the Unoccupied mode as configured under the local occupancy schedule accessible only from SCN. Schedule Number in Table SCHEDOVR (See Appendix A) must be configured to 1. If the Schedule Number is set to 0, the unit will operate in a continuous 24-hr Occupied mode. Control method must be configured to 0 (switch). See Table 8.

4 TO 20 mA INPUT — Unit operation is based on an external 4 to 20 mA signal input to the Energy Management Module (EMM).

LOW SOUND MODE OPERATION — All models are fac- tory configured with the Low Sound Mode disabled. In the Configuration mode under sub-mode OPT2, items for low sound mode select (LS.MD), low sound start time (LS.ST), low sound end time (LS.ND) and low sound capacity limit (LS.LT) are factory configured so that the chiller always runs as quietly as possible. This results in operation at increased saturated condensing temperature. As a result, some models may not be able to achieve rated efficiency. For chiller opera- tion at rated efficiency, disable the low sound mode or adjust the low sound mode start and stop times accordingly or set both times to 00:00 for rated efficiency operation 24 hours per day. In addition, the low sound capacity limit can be used to reduce overall chiller capacity, if required, by limiting the maximum to a user-configured percentage.

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