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Table 5 — Capacity Overrides

OVERRIDE

CAPACITY

CONTROL

VIEW/MODIFY

ON LID

TABLE

FIRST STAGE SETPOINT

SECOND STAGE

SET POINT

OVERRIDE

TERMINATION

Default

Value

Conﬁgurable

Range

HIGH CONDENSER

PRESSURE

EQUIPMENT SERVICE1 230 psi (1586 kPa) 150 to 250 psi

(1034 to 1724 kPa)

>Override Set point

+5 psi (35 kPa)

,Override Set Point

HIGH MOTOR

TEMPERATURE

EQUIPMENT SERVICE1 .200 F

(93 C)

150 to 200 F

(66 to 93 C)

.Override Set point

+10F(6C)

,Override Set Point

LOW REFRIGERANT

TEMPERATURE

(REFRIGERANT

OVERRIDE AT

TEMPERATURE)

EQUIPMENT SERVICE1 ,2F(1C)

Above Trippoint

2to5F

(1 to 3 C)

,Trippoint +

(Override DT—

1 F [0.56 C])

.Trippiont +

(Override DT + 2 F [1.2 C])

MANUAL

SLIDE VALVE

TARGET

CONTROL

ALGORITHM

MAINT01

Automatic −20 to 20

Counts

Manual control

cannot default

active control

Release of

Manual Control

MOTOR LOAD —

ACTIVE

DEMAND LIMIT

STATUS01 100% 40 to 100% >105% of

Set Point

2% Lower

Than Set Point

NOTE: [ ] indicates HFC-134a values.

Condenser Freeze Prevention — This control al-

gorithm helps prevent condenser tube freeze up by energiz-

ing the condenser pump relay. If the pump is controlled by

the PIC, starting the pump will help prevent the water in the

condenser from freezing. Condenser freeze prevention can

occur whenever the machine is not running except when it

is actively in Pumpdown or in Pumpdown Lockout with the

freeze prevention disabled (refer to Control Test table,

Pumpdown/Terminate Lockout screens). See Fig. 21. When

Pumpdown Lockout is initiated, if the CONDENSER

REFRIG TEMP is less than 40 F (4.4 C), then condenser

freeze prevention shall be disabled until termination of pump-

down lockout.

When the CONDENSER REFRIG TEMP is less than or

equal to the CONDENSER FREEZE POINT or the EN-

TERING CONDENSER WATER temperature is less than or

equal to the CONDENSER FREEZE POINT, then the CON-

DENSER WATER PUMP shall be energized until the CON-

DENSER REFRIG TEMP is greater then the CONDENSER

FREEZE POINT plus 5° F (2.7° C). An alarm will be gen-

erated if the machine is in PUMPDOWN mode and the pump

is energized. An alert will be generated if the machine is not

in PUMPDOWN mode and the pump is energized.

Either of the above on requirements may independently

result in the CONDENSER WATER PUMP being ener-

gized. However, both sets of off requirements must be met

in order for the pump to be deenergized.

Tower-Fan Relay — The tower fan relay, located in the

starter, is controlled by the PIC to energize and deenergize

as the pressure differential between cooler and condenser ves-

sels changes in order to prevent low condenser water tem-

perature and to maximize machine efficiency. The

tower-fan relay can only accomplish this if the relay has been

added to the cooling tower temperature controller. TheTOWER

FAN RELAY is turned on whenever the CONDENSER WA-

TER PUMP is running, ﬂow is veriﬁed, and the difference

between cooler and condenser pressure is more than 50 psi

(433 kPa) or ENTERING CONDENSER WATER is greater

than 85 F (29 C). The TOWER FAN RELAY is deenergized

when the condenser pump is off, ﬂow is lost, the evaporator

refrigerant temperature is less than the override temperature,

or the differential pressure is less than 45 psi (310 kPa) and

ENTERING CONDENSER WATER is less than 80 F (27 C).

IMPORTANT: A ﬁeld supplied water temperature con-

trol system should be installed. The system should main-

tain the leaving condenser water temperature at a tem-

perature that is 18 F (10 C) above the leaving chilled

water temperature.

The tower fan relay control is not a substitute for a job-

site condenser water temperature control. When used with

a Water Temperature Control system, the tower fan re-

lay control can be used to help prevent low condenser

water temperatures.

Auto. Restart After Power Failure — This option

may be enabled or disabled, and may be viewed/modiﬁed on

the Equipment Conﬁguration menu Conﬁg table. If enabled,

the chiller will start up automatically after a single cycle drop-

out, low, high, or loss of voltage has occurred, and the power

is within ±10% of normal. The start inhibit timers are ig-

nored during this type of start-up.

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