Anticipation Control Status Messages - York YCAS0098EB Installation Operation & Maintenance

Micro Panel Contents
Pump Down:
S Y S 1 P U M P I N G
S Y S 2 P U M P I N G
This message indicates that both refrigerant systems
are in a pumpdown cycle. Pumpdown display messages
occur on shutdowns where the cooling load has been
met, or when a system switch is turned OFF. Note that
only one compressor could be pumping down, as shown
in the following display:
S Y S 1 P U M P I N G
S Y S 2 C O M P
See Section 1.18 (page 130) for details of pumpdown
control.
Incorrect Refrigerant Warning:
R E P R O G R A M
R E F R I G E R A N T
The incorrect Refrigerant Warning will occur if the
DIP Switch setting for refrigerant type and the type
programmed into the micro "at the factory" are not the
same. This message will be displayed until the non-pro-
grammable "factory" programmed refrigerant type and
DIP Switch setting agree.
Power Failure Warning:
The Power Failure Warning will only be displayed on
"power restoration" after a "power loss," if manual re-
start on power failure is selected under the PROGRAM
key (page 160). If manual restart on power failure has
been selected, the following warning message is dis-
played indefinitely on power restoration and the chiller
will not run until the UNIT Switch is cycled OFF-and-on
to restart the unit. This safety is available for users who
desire a chiller lock-out on power failure.
This is typically not a desirable
feature.
! ! P O W E R
C Y C L E U N I T
When this message appears, the chiller will not run and
the Unit Switch must be cycled OFF and ON to start
the unit.
136
D O W N
D O W N
D O W N
R U N N I N G
T Y P E O F
T O R U N
F A I L U R E ! !
S W I T C H
2.4 ANTICIPATION CONTROL STATUS
MESSAGES
Anticipation controls are built into the software to
prevent safety shutdowns by automatically overriding
the temperature controls, if system conditions approach
safety thresholds. This avoids total loss of cooling
resulting from a lockout by a safety control.
Anticipation controls monitor discharge pressure, motor
current and suction temperature for each compressor
and if maximum limits are approached, the slide valve
loading of the respective compressor will be reduced to
avoid exceeding the limit.
Displays of anticipation safety control messages and
their meanings are as follows:
Discharge Pressure Limiting:
S Y S # D S C H
S Y S # D S C H
Discharge Pressure Limiting takes effect when compres-
sor discharge pressure nears the point at which the high
pressure cutout would shut the system down. When the
above message appears, discharge pressure has exceeded
the programmable threshold and the compressor is being
unloaded in an effort to prevent shutdown on the high
pressure cutout. The operation of this safety is important
if condenser coils become dirty, if there is a problem with
the condenser fan operation, or if extreme ambient or
load conditions occur (see Section 8.2 / High Discharge
Pressure Unload Point [page166] for more details).
Compressor Motor Current Limiting:
S Y S # C U R R
S Y S # C U R R
The Motor Current Limiting message indicates that a
compressor motor current has reached a programmable,
Bas, or remote limit and the system is being unloaded to
assure that motor current does not become excessively
high causing a fault (see also Section 8.2 / High Motor
Current Unload Point, page 161; Section 3.5, Motor
Current Key, page 142; Section 1.10, page 128).
Suction Temperature Limiting:
S Y S # S U C T
S Y S # S U C T
The Suction Temperature Limiting message applies only
when the chiller is set for Water Cooling Mode (see
page 142). The message indicates that saturated suction
L I M I T I N G
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JOHNSON CONTROLS