Specifications

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When a safety shutdown occurs, the shutdown sequence

ﬁrst stops the compressor by deactivating the start relay. A

status message of ‘‘SHUTDOWN IN PROGRESS, COM-

PRESSOR DEENERGIZED’’is displayed. The guide vanes

are then brought to the closed position. The oil pump relay

and the chilled water/brine pump relay are shut down

60 seconds after the compressor stops. The condenser water

pump will be shut down when the CONDENSER REFRIG-

ERANT TEMP is less than the CONDENSER PRESSURE

OVERRIDE minus 5 psi (34 kPa) or is less than or equal to

the ENTERING CONDENSER WATER TEMP plus 3° F

(2° C). The stop-to-start timer will now begin to count down.

If the start-to-start timer is still greater than the value of the

start-to-stop timer, then this time is now displayed on the

LID.

Certain conditions during shutdown will change this

sequence:

• if the COMPRESSOR MOTOR LOAD is greater than 10%

after shutdown, or the starter contacts remain energized,

the oil pump and chilled water pump remain energized and

the alarm is displayed

• if the ENTERING CONDENSER WATER temperature is

greater than 115 F (46 C) at shutdown, the condenser pump

will be deenergized after the 1CR compressor start relay

• if the machine shuts down due to low refrigerant tempera-

ture, the chilled water pump will stay running until the

LEAVING CHILLED WATER is greater than CONTROL

POINT, plus 5° F (3° C)

Automatic Soft StopAmps Threshold — The SOFT

STOP AMPS THRESHOLD closes the guide vanes of the

compressor automatically when a non-recycle, non-alarm stop

signal occurs before the compressor motor is deenergized.

If the STOP button is pressed, the guide vanes close to a

preset amperage percent or until the guide vane is less than

2% open. The compressor will then shut off.

If the machine enters an alarm state or if the compressor

enters a RECYCLE mode, the compressor will be deener-

gized immediately.

To activate SOFT STOP AMPS THRESHOLD, view the

bottom of Service1 table. Set the SOFT STOPAMPS THRESH-

OLD value to the percentage amps at which the motor will

shut down. The default setting is 100% amps (no Soft Stop).

When the SOFT STOPAMPS THRESHOLD is being ap-

plied, a status message ‘‘SHUTDOWN IN PROGRESS, COM-

PRESSOR UNLOADING’’ is shown.

Chilled Water Recycle Mode — The machine may

cycle off and wait until the load increases to restart again

when the compressor is running in a lightly loaded condi-

tion. This cycling of the chiller is normal and is known as

recycle. A recycle shutdown is initiated when any of the fol-

lowing conditions are present:

• when in LCW control, the LEAVING CHILLED WATER

temperature is more than 5° F (3° C) below the control

point, and the CONTROL POINT has not increased in the

last 5 minutes

• when ECW CONTROL OPTION is enabled, the ENTER-

ING CHILLED WATER temperature is more than 5° F

(3° C) below the CONTROL POINT, and the CONTROL

POINT has not increased in the last 5 minutes

• when the LEAVING CHILLED WATERtemperature is within

3° F (2° C) of the BRINE REFRIG TRIPPOINT

When the machine is in RECYCLE mode, the chilled wa-

ter pump relay remains energized so that the chilled water

temperature can be monitored for increasing load. The re-

cycle control uses RECYCLE RESTART DELTA T to check

when the compressor should be restarted. This is an operator-

conﬁgured function which defaults to 5° F (3° C). This value

is viewed/modiﬁed on the Service1 table. The compressor

will restart when:

• in LCW CONTROL the LEAVING CHILLED WATER tem-

perature is greater than the CONTROL POINT plus the RE-

CYCLE RESTART DELTA T; or

• in ECW CONTROL, the ENTERING CHILLED WATER

temperature is greater than the CONTROL POINT plus the

RECYCLE RESTART DELTA T

Once these conditions are met, the compressor shall ini-

tiate a start-up, with a normal start-up sequence.

An alert condition may be generated if 5 or more RE-

CYCLE STARTUPs occur in less than 4 hours. This exces-

sive recycling can reduce machine life. Compressor recycling

due to extremely low loads should be reduced. To reduce

compressor recycling, use the time schedule to shut the ma-

chine down during low load operation or increase the ma-

chine load by running the fan systems. If the hot gas bypass

is installed, adjust the values to ensure that hot gas is ener-

gized during light load conditions. Increase the RECYCLE

RESTART DELTA T on the Service1 table to lengthen the

time between restarts.

The machine should not be operated below design

minimum load without a hot gas bypass installed on the

machine.

A—START INITIATED — Prestart checks made; evaporator

pump started

B—Condenser water pump started (5 seconds after A)

C—Water ﬂows veriﬁed (30 seconds to 5 minutes maximum

after B). Chilled water temperatures checked against con-

trol point. Guide vanes checked for closure. Oil pump started;

tower fan control enabled.

D—Oil pressure veriﬁed (15 seconds minimum, 300 seconds

maximum after C)

E—Compressor motor starts, compressor ontime and service

ontime start, 15-minute inhibit timer starts (10 seconds af-

ter D)

F—SHUTDOWN INITIATED — Compressor motor stops, com-

pressor ontime and service ontime stops, and 1-minute in-

hibit timer starts.

G—Oil pump and evaporator pumps deenergized (60 seconds

after F). Condenser pump and tower fan control may con-

tinue to operate if condenser pressure is high. Evaporator

pump may continue if in RECYCLE mode.

O/A — Restart permitted (both inhibit timers expired) (minimum of

15 minutes after E; minimum of 1 minute after F).

Fig. 22 — Control Sequence