Carrier 23XL Spezifikationen PDF herunterladen (Seite 32)

Water/Brine Reset — Three types of chilled water or

brine reset are available and can be viewed or modiﬁed on

the Equipment Conﬁguration menu Conﬁg table.

The default screen status message indicates when the chilled

water reset is active. The CONTROL POINT, on the

Status01 table, indicates the machine’s reset temperature.

To activate a reset type, input all conﬁguration informa-

tion for that reset type in the Conﬁg table. Then input the

reset type number in the DISABLE/ENABLE input line.

1. Reset Type 1 (Requires optional 8-input module) — Au-

tomatic chilled water temperature reset based ona4to

20 mA input signal. This type permits up to ±30° F

(±16° C) of automatic reset to the chilled water or brine

temperature set point, based on the input froma4to

20 mA signal. This signal is hardwired into the number

one 8-input module.

If the 4 to 20 mA signal is externally powered from the

8-input module, the signal is wired to terminals J1-5(+)

and J1-6(−). If the signal is to be internally powered by

the 8-input module (for example, when using variable re-

sistance), the signal is wired to J1-7(+) and J1-6(−). The

PIC must now be conﬁgured on the Service2 table to en-

sure that the appropriate power source is identiﬁed.

2. Reset Type 2 (Requires optional 8-input module) — Au-

tomatic chilled water temperature reset based on a

remote temperature sensor input. This type permits

±30° F (±16° C) of automatic reset to the set point based

on a temperature sensor wired to the number one 8-input

module (see wiring diagrams or certiﬁed drawings).

The temperature sensor must be wired to terminal J1-19

and J1-20.

To conﬁgure Reset Type 2, enter the temperature of the

remote sensor at the point where no temperature reset will

occur. Next, enter the temperature at which the full amount

of reset will occur. Then, enter the maximum amount of

reset required to operate the machine. Reset Type 2 can

now be activated.

3. Reset Type 3 — Automatic chilled water temperature re-

set based on cooler temperature difference. This type of

reset will add ±30° F (±16° C) based on the temperature

difference between entering and leaving chilled water tem-

perature. This is the only type of reset available without

the need of the number one 8-input module. No wiring is

required for this type as it already uses the cooler water

sensors.

To conﬁgure Reset Type 3, enter the chilled water tem-

perature difference (the difference between entering and

leaving chilled water) at which no temperature reset oc-

curs. This chilled water temperature difference is usually

the full design load temperature difference. The differ-

ence in chilled water temperature at which the full amount

of reset will occur is now entered on the next input line.

Next, the amount of reset is entered. Reset Type 3 can

now be activated.

Demand Limit Control, Option — (Requires Op-

tional 8-Input Module) —

The demand limit may be

externally controlled witha4to20mAsignal from an en-

ergy management system (EMS). The option is set up on the

Conﬁg table. When enabled, the control is set for 100% de-

mand with 4 mA and an operator conﬁgured minimum de-

mand set point at 20 mA.

The Demand Reset input from an energy management sys-

tem is hardwired into the number one, 8-input module. The

signal may be internally powered by the module or exter-

nally powered. If the signal is externally powered, the

signal is wired to terminals J1-1(+) and J1-2(−). If the signal

is internally powered, the signal is wired to terminals J1-

3(+) and J1-2(−).

Hot Gas Bypass (Optional) Algorithm (See

Fig. 24 and 25) —

If a hot gas bypass solenoid valve is

present, and the hot gas bypass option on the SERVICE1

table is enabled, this operator conﬁgurable feature can de-

termine if load conditions are too low for the compressor

and then take corrective action.

The algorithm ﬁrst determines if corrective action is nec-

essary. This is done by checking two sets of operator con-

ﬁgured data points, which are the MINIMUM and the

MAXIMUM Load Points, (T1/P1;T2/P2). These points have

default settings for each type of refrigerant, HCFC-22 or HFC-

134a, as deﬁned on the SERVICE1 table, and on Table 3.

These settings and the algorithm logic are graphically dis-

played in Fig. 24 and 25. The two sets of load points on this

graph (default settings are shown) describe a line which the

algorithm uses to activate the hot gas bypass. Whenever the

temperature difference between the entering and leaving chilled

water is on the left side of the line on the graph (as deﬁned

by the MINIMUM and MAXIMUM Load Points), the al-

gorithm will then energize the hot gas bypass valve to falsely

load the machine and prevent displacement of oil. If the ac-

tual values are on the right side of the line, the algorithm

takes no action.

LEGEND

DP—Condenser Pressure-

Cooler Pressure

DT—ECW-LCW

ECW — Entering Chilled

Water Temperature

LCW — Leaving Chilled

Water Temperature

HGBP — Hot Gas Bypass

DEFAULT VALUES:

POINT HCFC-22 HFC-134a

2.5 2.5

50 30

10 10

200 170

Fig. 24 — 23XL Hot Gas Bypass (English)

LEGEND

DP—Condenser Pressure-

Cooler Pressure

DT—ECW-LCW

ECW — Entering Chilled

Water Temperature

LCW — Leaving Chilled

Water Temperature

HGBP — Hot Gas Bypass

DEFAULT VALUES:

POINT HCFC-22 HFC-134a

1.4 1.4

345 207

5.6 5.6

1379 1172

Fig. 25 — 23XL Hot Gas Bypass (SI)

1 2 ... 27 28 29 30 31 32 33 34 35 36 37 ... 103 104

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