Carrier 23XL Spezifikationen PDF herunterladen (Seite 23)

The proportional band can be viewed/modiﬁed on the LID.

There are two response modes, one for temperature re-

sponse above the control point, the other for response below

the control point.

The ﬁrst type is called PROPORTIONAL INC BAND and

it can slow or quicken slide valve response to chilled water/

brine temperature above DEADBAND. The PROPOR-

TIONAL INC BAND can be adjusted from a setting of 5 to

10; the default setting is 6.5. PROPORTIONAL DEC BAND

can slow or quicken slide valve response to chilled water

temperature below control point plus deadband. It can be ad-

justed on the LID from a setting of 5 to 10, and the default

setting is 6.0. Increasing either of these settings will cause

the slide valve to respond slower than a lower setting.

The PROPORTIONAL ECW GAIN can be adjusted at the LID

display for values of 1, 2, or 3, with a default setting of 2.

Increase this setting to increase slide valve response to a change

in entering cooler water temperature. The proportional bands

and gain may be viewed/modiﬁed on the Equipment Service

table, Service3 selection.

DEMAND LIMITING — The PIC will respond to the AC-

TIVE DEMAND LIMIT set point by limiting the closing of

the slide valve. It will compare the set point to either COM-

PRESSOR MOTOR LOAD or COMPRESSOR MOTOR

CURRENT (percentage), depending on how the control is

conﬁgured for the DEMAND LIMIT SOURCE which is ac-

cessed on the SERVICE1 table. The default setting is cur-

rent limiting.

MACHINE TIMERS — The PIC maintains 2 runtime clocks,

known as COMPRESSOR ONTIME and SERVICE ON-

TIME. COMPRESSOR ONTIME indicates the total lifetime

compressor run hours. This timer can register up to 500,000

hours before the clock turns back to zero. The SERVICE ON-

TIME is a resettable timer that can be used to indicate the

hours since the last service visit or any other reason. The

time can be changed through the LID to whatever value is

desired. This timer can register up to 32,767 hours before it

rolls over to zero.

The chiller also maintains a 15-minute start-to-start timer

and a 1-minute stop-to-start timer (PSIO Software Version

13 and higher). A 3-minute stop-to-start timer is on PSIO

Version 12 and lower. These timers limit how soon the ma-

chine can be started. See the Start-Up/Shutdown/Recycle Se-

quence section on page 37 for operational information.

OCCUPANCY SCHEDULE — This schedule determines when

the chiller is either occupied or unoccupied. See Fig. 20

and 21.

PSIO Software Version 12 and Lower — Whenever the chiller

is in the LOCAL mode, the machine will start when Occu-

pancy Schedule 01 indicates occupied. When in CCN mode,

Occupancy Schedule 02 is used. The machine will shut down

when the schedule goes to UNOCCUPIED. The schedule

can be set up to follow the building schedule or to be 100%

OCCUPIED if the operator wishes the machine to start when-

ever the PIC is in LOCAL mode. The schedule also can be

bypassed by forcing the Start/Stop command on the PIC sta-

tus screen to start. The schedule also can be overridden to

keep the unit in an OCCUPIED mode for up to 4 hours, on

a one-time basis.

PSIO Software Version 13 and Higher — The Local Time

Schedule is Schedule 01. The Ice Build Time Schedule is

Schedule 02 and the CCN Default Time Schedule is Sched-

ule 03. The CCN schedule number is deﬁned on the Conﬁg

table in the Equipment Conﬁguration table on page 25. The

schedule number can change to any value from 03 to 99. If

this schedule number is changed on the Conﬁg table, the op-

erator must use the Attach to Network Device table

to upload the new number into the schedule screen. See

Fig. 21.

Each schedule consists of from one to 8 occupied/unoccupied

time periods, set by the operator. These time periods can be

enabled to be in effect (or not in effect) on each day of the

week and for holidays. The day begins with 0000 hours and

ends with 2400 hours. The machine is in OCCUPIED mode

unless an unoccupied time period is in effect.

Figure 22 shows a typical office building time schedule,

with a 3-hour, off-peak cool down period from midnight to

3 a.m., following a weekend shutdown. Example: Holiday

periods are unoccupied 24 hours per day. The building op-

erates Monday through Friday, 7:00 a.m. to 6:00 p.m., with

a Saturday schedule of 6:00 a.m. to 1:00 p.m., and includes

the Monday midnight to 3:00 a.m. weekend cool-down

schedule.

NOTE: This schedule is for illustration only and is not in-

tended to be a recommended schedule for chiller operation.

Safety Controls — The PIC monitors all safety control

inputs, and, if required, shuts down the machine, or limits

the slide valve to protect it from possible damage from any

of the following conditions:

• high motor winding temperature

• high discharge temperature

• low discharge superheat temperature (Frame 1 and 2

machines)

• low oil pressure

• high oil ﬁlter pressure drop

• low oil level

• low cooler refrigerant temperature

• condenser high pressure

• inadequate water/brine cooler and condenser ﬂow

• high, low, or loss of voltage

• excessive motor acceleration time

• excessive starter transition time

• lack of motor current signal

• excessive motor amps

• motor power supply phase reversal

• temperature sensor and transducer faults

Starter faults or optional protective devices within the starter

can shut down the machine. These devices are dependent on

what has been purchased as options.

If compressor motor overload occurs, check the motor

for grounded or open phases before attempting a

restart.

If the controller initiates a safety shutdown, it displays the

fault on the LID display with a primary and a secondary mes-

sage. It also energizes an alarm relay in the starter and blinks

the alarm light on the control center. The alarm is stored in

memory and can be viewed in the PIC alarm table along with

a message for troubleshooting.

To give more speciﬁc operating condition warning, the op-

erator also can deﬁne alert limits on various monitored in-

puts. Safety contact and alert limits are deﬁned in Table 4.

Alarm and alert messages are listed in the Troubleshooting

Guide section, page 68.

SHUNT TRIP — The shunt trip function of the PIC is a safety

trip. The shunt trip is wired from an output on the SMM to

the motor circuit breaker. If the PIC tries to shutdown the

compressor through normal shutdown procedure but is un-

successful for 30 seconds, the shunt trip output is energized

and causes the circuit breaker to trip off. If ground fault pro-

tection has been applied to the starter, the ground fault trip

will also energize the shunt trip to trip the circuit breaker.

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