Carrier 23XL Especificações descarregar pdf (Página 38)

Shutdown Sequence — Shutdown of the machine can

occur if any of the following events happen:

• the STOP button is pressed for at least one second (the

alarm light will blink once to conﬁrm stop command)

• recycle condition is present (see Chilled Water Recycle Mode

section)

• time schedule has gone into UNOCCUPIED mode (ma-

chine protective limit has been reached and machine is in

alarm)

• the start/stop status is overridden to stop from the CCN

network or the LID

When a stop signal occurs, the shutdown sequence ﬁrst

stops the compressor by deactivating the start relay. The slide

valve decrease timer is activated for 3 minutes to open the

slide valve. The condenser water pump relay is shut down

30 seconds after the compressor run contact is open and mo-

tor load is less than 10%. The service ontime and compres-

sor ontime timers are deactivated. The 3-minute stop-

to-start timer will now begin to count down. If the

15-minute start-to-start timer is still greater than 3 minutes,

then this time is now displayed. Last, the chilled water/brine

pump is shut down.

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 chilled water pump and the condenser water pump re-

main energized and the alarm is displayed

• if the ENTERING CONDENSER WATER temperature is

less than 115 F (46 C) [125 F (52 C)] and the condenser

refrigerant temperature is less than the CONDENSER

FREEZE POINT plus 5°F(3°C)atshutdown, the Con-

denser Pump Control algorithm will determine when the

condenser pump will be deenergized after shutdown

• 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 Stop Amps Threshold (PSIO Soft-

ware Version 13 and Higher)

— The SOFT STOP

AMPS THRESHOLD unloads the slide valve of the com-

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

signal is emitted before the compressor motor is

deenergized.

If the STOP button is pressed, the slide valve unloads to

a preset amperage percent. Then, the compressor will shut

off.

If the machine enters an Alarm state or if the compressor

enters a RECYCLE mode, the compressor will be de-

energized immediately.

To activate SOFT STOP AMPS THRESHOLD, view the

bottom of Service1 screen. Set the Soft Stop Amps Thresh-

old value to the percentage amps that the slide valve will

achieve the motor will be shut down. The default setting is

100% (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 — When the compres-

sor is running in a lightly loaded condition, the machine may

cycle off and wait until the load increases before restarting.

This cycling of the chiller is normal and is known as re-

cycle. 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 10 minutes

• when the LEAVING CHILLED WATER temperature is within

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

A—START INITIATED: Pre-start checks are made; evaporator

pump started

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

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

D—Chilled water temperature checked against control point;

tower fan control enabled; slide valve decrease timer checked

to verify slide valve position

E—Refrigerant type veriﬁed (up to 3 minutes after D).

F—Compressor motor starts; phase reversal conditions moni-

tored; compressor ontime and service ontime start;

15-minute inhibit timer starts (10 seconds after E)

G—Shutdown initiated: Compressor motor stops; compressor

ontime and service ontime stop; 3-minute inhibit timer starts

on PSIO Software Version 8 and 12 and 1-minute inhibit

timer on PSIO Software Version 13 and higher; slide valve

decrease activated for 1 minute

H—Evaporator pump deenergized (30 seconds after G); con-

denser pump and tower fan control may continue to oper-

ate if condenser pressure is high; evaporator pump may

continue if in RECYCLE mode

I—Slide valve decrease timer expires (3 minutes after G)

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

15 minutes after F; minimum of 1 minute after G)

Fig. 28 — Control Sequence

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 103 104

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