Carrier 19XR Spécifications télécharger pdf (Page 46)

START-UP/SHUTDOWN/

RECYCLE SEQUENCE (Fig. 26)

Local Start-Up —

Local start-up (or a manual start-up) is

initiated by pressing the menu softkey on the default

CVC screen. Local start-up can proceed when the chiller

schedule indicates that the current time and date have been

established as a run time and date, and after the internal

15-minute start-to-start and the 1-minute stop-to-start inhibit

timers have expired. These timers are represented in the START

INHIBIT TIMER and can be viewed on the MAINSTAT screen

and DEFAULT screen. The timer must expire before the chiller

will start. If the timers have not expired the RUN STATUS pa-

rameter on the MAINSTAT screen now reads TIMEOUT.

NOTE: The time schedule is said to be “occupied” if the

OCCUPIED ? parameter on the MAINSTAT screen is set to

YES. For more information on occupancy schedules, see the

sections on Time Schedule Operation (page 20), Occupancy

Schedule (page 34), and To Prevent Accidental Start-Up

(page 65), and Fig. 19.

If the OCCUPIED ? parameter on the MAINSTAT screen

is set to NO, the chiller can be forced to start as follows. From

the default CVC screen, press the and

softkeys. Scroll to highlight MAINSTAT. Press the

softkey. Scroll to highlight CHILLER START/STOP. Press the

softkey to override the schedule and start the chiller.

NOTE: The chiller will continue to run until this forced start is

released, regardless of the programmed schedule. To release

the forced start, highlight CHILLER START/STOP from the

MAINSTAT screen and press the softkey. This

action returns the chiller to the start and stop times established

by the schedule.

The chiller may also be started by overriding the time

schedule. From the default screen, press the and

softkeys. Scroll down and select the current

schedule. Select OVERRIDE, and set the desired override

time.

Another condition for start-up must be met for chillers that

have the REMOTE CONTACTS OPTION on the EQUIP-

MENT SERVICE screen set to ENABLE. For these chillers,

the REMOTE CONTACTS INPUT parameter on the MAIN-

STAT screen must be CLOSED. From the CVC default screen,

press the and softkeys. Scroll to high-

light MAINSTAT and press the softkey. Scroll

down the MAINSTAT screen to highlight REMOTE START

CONTACT and press the softkey. Then, press the

softkey. To end the override, select REMOTE CON-

TACTS INPUT and press the softkey.

Once local start-up begins, the PIC II performs a series of

pre-start tests to verify that all pre-start alerts and safeties are

within the limits shown in Table 4. The RUN STATUS parame-

ter on the MAINSTAT screen line now reads PRESTART. If a

test is not successful, the start-up is delayed or aborted. If the

tests are successful, the chilled water/brine pump relay ener-

gizes, and the MAINSTAT screen line now reads STARTUP.

Five seconds later, the condenser pump relay energizes.

Thirty seconds later the PIC II monitors the chilled water and

condenser water flow devices and waits until the WATER

FLOW VERIFY TIME (operator-configured, default 5 minutes)

expires to confirm flow. After flow is verified, the chilled water

temperature is compared to CONTROL POINT plus 1/2

CHILLED WATER DEADBAND. If the temperature is less

than or equal to this value, the PIC II turns off the condenser

pump relay and goes into a RECYCLE mode.

If the water/brine temperature is high enough, the start-up

sequence continues and checks the guide vane position. If the

guide vanes are more than 4% open, the start-up waits until the

PIC II closes the vanes. If the vanes are closed and the oil pump

pressure is less than 4 psi (28 kPa), the oil pump relay energiz-

es. The PIC II then waits until the oil pressure (OIL PRESS

VERIFY TIME, operator-configured, default of 40 seconds)

reaches a maximum of 18 psi (124 kPa). After oil pressure is

verified, the PIC II waits 40 seconds, and the compressor start

relay (1CR) energizes to start the compressor.

Compressor ontime and service ontime timers start, and the

compressor STARTS IN 12 HOURS counter and the number of

starts over a 12-hour period counter advance by one.

Failure to verify any of the requirements up to this point will

result in the PIC II aborting the start and displaying the applica-

ble pre-start mode of failure on the CVC default screen. A pre-

start failure does not advance the STARTS IN 12 HOURS

counter. Any failure after the 1CR relay has energized results in

a safety shutdown, advances the starts in 12 hours counter by

one, and displays the applicable shutdown status on the CVC

display.

LOCAL

MENU STATUS

SELECT

START

RELEASE

SCHEDULE

MENU STATUS

SELECT

RELEASE

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 after B).

Chilled water temperatures checked against control 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 after D), total com-

pressor starts advances by one, and the number of starts over a

12-hour period advances by one.

F — SHUTDOWN INITIATED — Compressor motor stops; compressor

ontime and service ontime stop, and 1-minute inhibit timer starts.

G — Oil pump and evaporator pumps deenergized (60 seconds after F).

Condenser pump and tower fan control may continue 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. 26 — Control Sequence

1 2 ... 41 42 43 44 45 46 47 48 49 50 51 ... 135 136

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Carrier 19XR Spécifications Page 46

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